Immune System

IMMUNITY DEFINITION
“The ability of human body to resist almost all types of micro-organisms, their toxins if any, foreign cells & abnormal cells of the body is termed as “Immunity”
IMMUNOLOGY
DEFINITION
“The study of functioning & disorders of Immune system is termed as “Immunology”.
IMMUNE SYSTEM
Immunity is conferred to animals through the activities of the Immune System, which combats infectious agents.
DEFINITION
“Immune System is a collection of cells & proteins that work to protect the body from potentially harmful, infectious micro-organisms”
MAIN FUNCTIONS OF IMMUNE SYSTEM
Protection of body from all types of micro organisms & toxins that tend to damage the tissues and organs of body.
ADDITIONAL FUNCTIONS
Immune system also play important role in:

• Control of cancer
• Allergy
• Hypersensitivity
• Rejection problems when organs or tissues are transplanted.

DIVISIONS OF IMMUNE SYSTEM
Immune system can be divided into two functional divisions:
1. Innate Immunity System
2. Acquired Immunity System
INNATE IMMUNITY
DEFINITION
“The NON SPECIFIC type of immunity which result from general processes , rather than from processes directed at specific disease organism (Such as antigen –antibody reaction) is called. INNATE OR NATURAL IMMUNITY & the system which is responsible for this type of immunity is called Innate IMMUNITY System.
TYPES OF BARRIERS PROVIDED BY INNATE IMMUNITY SYSTEM
This system provides two types of barriers:
Physical Barrier
Chemical Barrier
PHYSICAL BARRIERS

• SKIN
• MUCOUS MEMBRANE & etc.

CHEMICAL BARRIERS

• Lysozyme
• Gastric juice (Acidic secretion of stomach) & etc.

FIRST LINE OF DEFENCE
Skin, Mucous membrane & their secretions act as “First line of Defence”
1. SKIN
The intact skin provides an impenetrable barrier to the vast majority of infectious agents.
2. MUCOUS MEMBRANES
Most of the micro-organisms can enter only through the mucous membranes that lines the digestive, respiratory & urogenital tracts. However these areas are protected by movements of mucous & secretions (e.g Lysozyme in tears) to destroy many microbs.
3. ACIDIC SECRETIONS
Most of he microorganisms present in food or trapped in swallowed mucus from the upper respiratory tracts are destroyed by highly acidic gastric juice of stomach.
SECOND LINE OF DEFENSE
If some how micro-organisms are able to penetrate the outer layer of the skin or mucous membrance, they encounter a second line of Defence offered by Innate Immunity system.
It is non specific & comprises of
1. PHAGOCYTES
2. ANTIMICROBIAL PROTEINS
3. INFLAMMATORY RESPONSE
1. PHAGOCYTES
Phagocytes are certain type of WBC’S which can injest internalize & destroy the particles including infectious agents.
EXAMPLES OF PHAGOCYTIC CELLS
NEUTROPHILS
MACROPHAGES
NEUTROPHILS
Neutrophils (Polymorphonuclear Neutrophiles are short lived phagocytic cells which can ingest the bacteria or any foreign matter very actively.
MACROPHAGES (BIG EATERS)
The other phagocytic cells, the MONOCYTE can develop into large LONG-LIVED MACRO PHAGES when they reside in various tissues of body. ALSO CALLED AS ANTIGEN PRESENTING CELLS.
Macrophages not only destroy individual micro organisms but also play a crucial rule in further immune response by “Presenting” parts of that microorganisms to other cells of immune system. For this reason, they are termed as “ANTIGEN PRESENTING CELLS.
NATURAL KILLER (NK ) CELLS
Natural killer cells (NK Cells ) are the large lymphocytes, which destroy the

• Virally infected own cells of the body
• Foreign cells
• Abnormal cells (cancerous cells)

MECHANISM OF ACTION (CYTOTOXICITY)
NK cells do not phagocytize the target cells, instead, they bind to their target cells, release some PORE FORMING PROTEINS (PERFORINS), that literally punch large round holes in the membrane of attacked cells & eventually cause lysis of the target cells. This kind of destroying the target cells is called “CYTOTOXICITY”
2. ANTIMICROBIAL PROTEINS
EXAMPLES

• Important antimicrobial proteins are:
• Lysozyme
• Compliment proteins
• Interferon

LYSOZYMES
Lysozyme, is a mucolytic polysaccharide that causes the LYSIS OF BACTERIA it is present in TEARS, SALIVA, & MUCUS SECRETION.
COMPLEMENT PROTEINS
Complement is a collective terms that describes a system of about 20 PROTEINS, many of which are INACTIVE ENZYME PRECURSORS. The principal actors in this system are 11 Proteins. All these proteins are present among the Plasma Proteins.
ACTIVATION OF COMPLIMENT PROTEINS
These proteins can be activated by two ways.

• CLASSICAL PATH WAY-Act in Adaptive Immunity system.
• ALTERNATIVE PATH WAY- Act in Innate Immunity System.

FUNCTIONS
Main functions of compliment proteins are as follows:
1. DIRECT LYSIS OF BACTERIA
2. PROMOTE THE PHAGOCYTOSIS OF BACTERIA
3. NEUTRILIZATION OF VIRUSES
4. CHEMOATTRACTANTS FOR MACROPHAGES.
INTERFERONS (ANTIVIRAL AGENTS)
Interferon are secreted by virally infected cells or some lymphocytes to induce a state of ANTI VIRAL RESISTANCE in unaffected tissues of the body.
3. INFLAMMATION
Inflammation is the body’s reaction to an injury or by entry of micro organisms.
EFFECTS OF INFLAMMATION
A cascade of chemical reactions take place during inflammatory response.
1. When injured, BASOPHILS and MAST CELLS release a substance called HISTAMINE which causes.

• Increased permeability of adjacent capillaries.
• Local vasodilatation
• Increased leakage of capillaries.

2. Due to CHEMOTAXIS, Phagocytes & macrophages are attracted at the injured site. Thus Phagocytes literally eat up microorganisms, dirt, cell debris & etc forming pus.
SYMPTOMS
Redness, heat, swelling, pain in injured tissue.
FEVER -(ALSO CONTRIBUTES TO DEFENSE OF BODY)
In case of warm blooded animals, a no. of micro organisms who escape away from inflammatory response to infect some large part of the body, trigger FEVER. It is usually caused by WBC’S, that release the substance called as PYROGEN.
FUNCTIONS

• High fever is dangerous but moderate fever contributes to the defense of the body.
• It inhibits the growth of micro-organisms.
• May speed up the repair of damaged tissues.
• Facilitates the phagocytosis, increase the production of interferons.

ADAPTIVE IMMUNE SYSTEM
DEFINITION
“The specific type of Immunity which does not develop until after the body is first attacked by a bacterial disease or a toxin, is called “Adaptive or Acquired Immunity”. The system which provides this type of immunity is called “ADAPTIVE or ACQUIRED IMMUNE SYSTEM”

OR
“Acquired Immunity is provided by special Immune System that form Antibodies & activated lymphocytes that attack & destroy the specific organisms or toxins. This is the THIRD LINE OF DEFENCE.
DEVELOPMENT OF IMMUNE SYSTEM (LYMPHOCYTES ARE THE BASIS OF ADAPTIVE IMMUNE SYSTEM)
Acquired Immune system is actually the product of body’s Lymphocytic system. The responses of adaptive Immune system is provided by Lymphocytes.
TYPES OF LYMPHOCYTES
During fetal development, all lymphocytes come from Bone Marrow. But depending upon their migration & maturity, they can be divided into two populations.
1. “T” – Cells or “T” LYMPHOCYTES
2. “B” – Cells or “B” LYMPHOCYTES.
1. “T” LYMPHOCYTES
DEFINITION
“The lymphocytes that are destined to eventually form ACTIVATED “T” LYMPOCYTES first migrate to & then mature in THYMUS GLAND, that is why, they are called as “T” LYMPHOCYTES”
FUNCTIONS
These are responsible for “CELL-MEDIATED IMMUNITY
2. “B” LYMPHOCYTES
DEFINITION
“The lymphocytes that are destined to form ANTIBODIES are processed first in the LIVER (before birth) & then in BONE MARROW (after the birth). This population of cells was first discovered in birds where processing occurs in BURSA OF FABRICIUS (not found in mammals), hence they are called as “B” LYMPHOCYTES.”
FUNCTIONS
These are responsible for HUMORAL IMMUNITY
ADAPTIVE IMMUNE SYSTEM IS INITIATED BY ANTIGENS
In order to develop a specific immune response, the immune system must recognize the invading organisms and / or foreign proteins from its self tissues & proteins.
ANTIGEN
Any foreign substance, that elicit the immune response is called antigen. In general Antigens are proteins or large polysaccharides.
RESPONSE OF IMMUNE SYSTEM TO ANTIGEN
The immune system responds to an antigen by ACTIVATING LYMPHOCYTES & PRODUCING ANTIBODIES (Soluble Proteins). The antibody combines with antigen & helps to eliminate it from the body.
BASIC TYPES OF ADAPTIVE IMMUNITY
The adaptive immune system mounts two types of attacks on invading micro-organisms.
1. HUMORAL IMMUNITY
2. CELL MEDIATED IMMUNITY (CMI)
1. HUMORAL IMMUNITY
DEFINITION
“The immunity which is mediated by circulating antibodies produced by B-lymphocytes is called “ HUMORAL IMMUNITY”.

MAJOR FUCTIONS OF HUMORAL IMMUNITY
Humoral Immunity provides major defence against “BACTERIAL INFECTIONS
MECHANISM OF ACTION OF B CELLS
“B” CELL RECEPTORS
Each B-cell has specific type of antibodies on its cell surface. This antibody serves as ANTIGENIC RECEPTOR.
ACTIVATION OF SPECIFIC “B” CELLS
On entry of foreign antigen, those B cells specific for that antigen enlarge immediately, becomes activated & form two types of cells:
1. PLASMA CELLS
2. MEMORY CELLS
1. PLASMA CELLS
The activated B-cells proliferate rapidly & transform into enlarged effectors cells called plasma cells.
FUNCTION
Plasma cells secrete ANTIBODIES into the circulation that help to eliminate that particular antigen.
ACTIONS OF ANTIBODIES.
After the formation of antigen-antibody complex antibody can inactivate the invading agent in one of the several ways.

• By activation of complement system that cause the Lysis.
• Direct Phagocytosis.
• Neutralization of the toxins released by bacteria.
• Agglutination of microorganism.

2. MEMORY CELLS
DEFINITION
Some of the activated B-cells don’t go on to form the plasma cells but instead, form moderate number of new B-cells, which don’t secrete antibodies such cells are called as Memory cells.

FUNCTIONS
The memory cells play important role in future immunity to this specific organism in case of re-infection.
2. CELL MEDIATED IMMUNITY (CMI)
DEFINITION
The second type of acquired immunity is achieved through the formation of large number of Activated LYMPHOCYTES. This is called cell mediated or T-cell immunity.
FUNCTIONS OF CMI

• CMI is responsible for delayed allergic reactions & rejection of transplantation of foreign tissue.
• It provides major defence against infections due to VIRUSES, FUNGI, TUBERCLE BACILLI & some parasites.
• It also provides defence against TUMOUR CELLS.

MECHANISM OF ACTION OF “T”-CELLS.
T-CELL RECEPTORS (TCRS)
Antigens bind with specific RECEPTOR MOLECULES on the surface of T-Cells, in the same way that they bind the antibodies.
ACTIVATION OF SPECIFIC “T” CELLS.
On exposure to proper antigen, the “T” cells of specific type proliferate & release large no. of activated T-Cells.
SEVERAL TYPES OF “T” CELLS
Different types of T cells are classified into four major groups.
1. HELPER “T” CELLS
2. CYTOTOXIC “T” CELLS
3. SUPRESSER “T” CELLS
4. MEMORY “T” CELLS
1. HELPER “T” CELLS
Helper T cells are the MAJOR REGULATOR of all the immune functions.
RECEPTORS
Helper T cell receptors actually recognize a combination of antigen fragment & one of the body’s own self marker called. “MAJOR HISTO-COMPATIBILITY” (MHC) CLASS II molecules on the surface of macrophages or B cells.
FUNCTIONS
Helper T-cells secrete the LYMPHOKINES which stimulate the production of both CYTOTOXIC & SUPRESSER TOXINS.
2. CYTOTOXIC “T” CELLS (KILLER CELLS)
RECEPTORS
Receptors on the surface of cytotoxic ‘T” cells recognize a combination of antigen fragment & self surface marker molecules called MHC CLASS I , found on every nucleated cells of its own body.
FUNCTIONS
They are especially lethal to virally infected cells. They also destroy the cancer cells, heart transplant cells & other foreign cells.
3. SUPRESSOR “T” CELLS
Along with helper cells, In supressor, T-cells are classified as Regulatory T-Cells
FUNCTIONS
After the conquerence of infection, they seems to shut off the immune response in both B-cells & cytotoxic T-cells.
4. MEMORY “T” CELLS
During CMI response, some T-cells turn into MEMORY CELLS
FUNCTION
Memory cells protect the body in case of reaction in future.
TYPES OF IMMUNE RESPONSE
The immune system has also the ability to memorize the antigen it has encountered. Thus upon subsequent exposure to the same pathogen responds in two different ways.
1. Primary Immune Response
2. Secondary Immune Response
1. PRIMARY IMMUNE RESPONSE
DEFINITION
The first exposure to an antigen to the immune system elicits formation of clones of effectors cells to develop specific immunity with in 5 to 10 days. This response of immune system is termed as Primary Immune response.
CHARACTERISTICS

• DELAYED APPEARANCE
• WEAK POTENCY
• SHORT LIFE

2. SECONDARY IMMUNE RESPONSE
DEFINITION
Subsequent exposure of same antigen causes a much more rapid & much more potent antibody response. This is called Secondary Immune response. It develops to it max. with in 3-5 days.
CHARACTERISTICS

• Rapid & quicker appearance
• Far more potent
• Longer duration (form antibodies for many months rather than for only a few weeks.)

BASIS OF SECONDARY RESPONSE (IMMUNOLOGICAL MEMORY)
The quicker secondary response is made possible due to ability called “Immunological Memory” of the immune system. It is based upon the long lasting memory cells produced with short lived effectors cells of pri immune response. The development of memory cells may provide life long protection against some diseases like chicken pox.
ACTIVE & PASSIVE IMMUNITY
ACTIVE IMMUNITY
DEFINITION
The immunity which is acquired by own immune response is called active immunity
FUNCTION OF ACTIVE IMMUNITY
Active immunity due to development of immunological memory provide LONG TERM PROTECTION, even in some diseases (e.g in chicken Pox ) life long protection is provided.
TYPES OF ACTIVE IMMUNITY
There are two types.
1. Natural active immunity
2. Artificial active Immunity
1. NATURAL ACTIVE IMMUNITY
DEFINITION
When the active immunity is acquired as a consequence of natural infection then it is called Natural active immunity”
2. ARTIFICIAL ACTIVE IMMUNITY
DEFINITION
Active immunity can be acquired artificially by vaccination. In this case it is said to be “ARTIFICIAL ACTIVE IMMUNITY”
PASSIVE IMMUNITY
DEFINITION
Temporary immunity which is achieved in a person without injecting an antigen, by transferring the antibodies, activated T-cells or both obtain from another person or even an animal, is called passive immunity.
FUNCTIONS OF PASSIVE IMMUNITY
Although, acquired passive immunity is short lived (last for 2-3 weeks), it boosts the immune response of the victim several folds.
TYPES OF PASSIVE IMMUNITY
There are 2 Types:
1. Natural passive Immunity
2. Artificial passive Immunity
1. NATURAL PASSIVE IMMUNITY
DEFINITION
When antibodies are transferred from one person to another of the same species during natural processes, then such immunity is called Natural passive immunity.

EXAMPLE
A pregnant woman passes some of the antibodies to her fetus through placenta. The first breast feeding, the colostrum, of mother pass certain antibodies to her newly born infant.
2. ARTIFICIAL PASSIVE IMMUNITY
DEFINITION
PASSIVE IMMUNITY can also be transferred artificially by introducing antibodies derived from animals or human being who are already actively immunized to that disease. This is called artificial passive immunity.

EXAMPLE
RABIES is treated in man by injecting antibodies derided from persons who have been already vaccinated against rabies. This confers the rapid immunity to combat the rapidly progressing rabies in new victim.
IMMUNIZATION
The process of inducing immunity as a preventive measure against certain infectious diseases is called immunization.
ADVANTAGES OF IMMUNIZATION
The incidence of number of diseases (e.g Diptheria, Measles) has declined dramatically since the introduction of effective immunization programmes. Some dread full diseases (e.g. Tuberclosis) is now under control.

Lymphatic System

MAIN FUNCTION OF LYMPHATIC SYSTEM All body tissues are bathed in a watery fluid derived from the blood stream. This intercellular or tissue fluid is formed when blood passes trough the capillaries. The capillary walls are permeable to all components of blood except the R.B.C’s & blood proteins. The fluid passes from the capillary into the intercellular spaces as the inter-cellular or tissue fluid. About 85% of the tissue fluid returns into the blood at the venous end of capillary. The rest 15 % of tissue fluid drains into lymphatic capillaries as lymph along with W.B.C’s, cell debris & micro organism like Bacteria , are transported back to the heart through lymphatic system.
COMPONENTS OF LYMPHATIC SYSTEM
Lymphatic System Consists of
1. Lymph
2. Lymphatic tissues
3. Lymphatic vessels or Lymphatics
4. Lymph nodes (type of lymphatic tissue)
DETAILS OF COMPONENTS
1. LYMPH
DEFINITION
“Lymph is the name given to the tissue fluid once it has entered a lymphatic vessel. OR It can be defined as “Colour less body fluid that contains lymphocytes (agranular WBC’S), small proteins & fats”.
EXPLANATION
Lymph is a medium of exchange between blood & body cells. It takes the fluid substances from cell of tissues & intercellular spaces, which cannot penetrate the blood capillaries.
2.LYMPHATIC TISSUES
DEFINITION
“Lymphatic tissues are a type of connective tissues that contain large no. of lymphocytes”
ORGANS THAT CONTAIN LYMPHATIC TISSUES
Lymphatic tissue is organized into following structures (organs).

• Lymph nodes
• Thymus
• Spleen
• Tonsils
• Some of the patches of tissues in vermiform appendix & in small intestine.

FUNCTION
Lymphatic tissue is essential for immunologic defenses of the body against viruses & bacteria.
3. LYMPHATICS
DEFINITION
Lymphatic vessels or lymphatics are blind tubes that assist the cardiovascular system in removal of tissue fluid from tissues spaces of the body, the vessels then return the fluid to the blood.
AREAS WHERE LYMPHATIC ARE NOT PRESENT
Lymphatics are present in all tissues & organs of the body except.

• Central Nervous System
• The eye ball
• Internal Ear
• Epidermis of Skin
• Cartilage & bone

TYPES
Two Types of Lymphatics are there:-
SMALL - LYMPH CAPILLARIES
LARGE - LYMPH VESSELS.
1. LYMPH CAPILLARIES
DEFINITION
“Lymph capillaries are a network of thin walled, anastomosing, microscopic vessels which are closed towards the tissue sinuses & drain the Lymph from tissues.”
2. LYMPH VESSELS
DEFINATION
The capillaries are in turn drained by lymph tubes having larger diameters & beaded appearance, called the Lymph vessels.
These vessels contain smooth muscles in them as well as Internal valves to prevent the back flow of Lymph. The Lymph circulates through the Lymph vessels by the contraction of surrounding skeletal muscles in one direction (towards the heart). These vessels converge into collecting ducts i.e right
Lymphatic duct & thoracic duct that drain into large veins at the root of neck.
4. LYMPH NODES
DEFINITION
“Lymph nodes are lymphoid tissue which are present through out the course of Lymphatics, through which the lymph must passes”
INTERNAL STRUCTURE
Each node consists of a thin, fibrous, outer capsule & an inner mass of lymphoid tissue.
AFFERENT VESSELS
Several small Lymphatics which carry the lymph into the lymph node are referred to as “Afferent vessels.”
EFFERENT VESSEL
A single large vessel which carry the lymph away from the node is called “Efferent vessel”
FUNCTION
Lymph nodes act as filters that trap the microorganisms & other foreign bodies in the lymph. The Lymphocytes & macro-phages present here, neutralize & engulf the microorganisms, respectively.
MAJOR FUNCTIONS OF LYMPHATIC SYSTEM.
From Text Book Pg. 379.
EDEMA
DEFINITION
“Whenever the tissue fluid accumulates rather than being drained into the blood by the lymphatic system, tissue & body cavities become swollen. This condition is known as “Edema”.

TYPES OF EDEMA
There are two types of Edema.
1. INTRACELLULAR
2. EXTRACELLULAR
1. INTRACELLULAR EDEMA
“Accumulation of excess of fluid within the cells causing cellular swelling is called “Intra cellular Edema. It usually occurs after severe extracellular Edema.
2. EXTRACELLULAR EDEMA
“Excess fluid accumulation in extra cellular spaces is called Extracellular Edema. ”
It is the most commonly occurring form of Edema.
FACTORS CAUSING EDEMA
Any factor that increases the tissue fluid high enough than normal value can cause excess tissue fluid volume causing edema. Some of these factor are as follows.

• High blood pressure
• Kidney failure
• Hart failure & etc.

CAUSES OF EDEMA
Following are three main causes of Edema.
1. HYPOPROTEINEMIA (SEVERE DIETARY PROTEIN DEFICIENCY)
When body is starving for Amino acids, it consumes its own blood proteins. This reduces the osmotic potential of the blood causing tissue fluid to accumulate in body tissues rather than being drawn back into capillaries, resulting in Edema.
2. LYMPHATIC OBSTRUCITON (COMMONEST CAUSE –FILARIASIS )
Another cause of edema is lymphatic obstruction, which results in more & more protein collection in the local tissue fluid hence, the increased volume. Commonest cause of lymphatic obstruction is FILARIASIS (infection by NEMOTODES) such condition is also called as “Elephantiasis” (because of swollen legs).
3. INCREASED PERMEABILITY OF CAPILLARIES (CAUSES-BURNS & ALLERGIC REACTIONS)
Sometimes the permeability of capillaries increase due to burns or allergic reactions, so blood proteins & plasma come out of capillaries & enter the tissue fluid thus causing Edema

Circulation of Blood

CARDIAC CYCLE Sequence of events which take pace during completion of one heart beat is called “Cardiac Cycle”
PHASES
(I) DIASTOLE
It is resting period of heart chambers.
II) SYSTOLE
During which heart’s chambers contract. In cardiac cycle, blood is circulated in whole body.
TYPES OF CIRCULATION
PULMONARY CIRCULATION
In pulmonary circulation following events take place.
RT. ATRIAL SYSTOL
First the blood from whole systems of body, except lungs enter in right Atrium through superior and Inferior vena cavae into the right atrium by atiral systole, blood comes into right ventricle from right atrium via Tricuspid valve.
RT. VENTRICLE SYSTOLE
After coming of blood into the Rt. Ventricle, it goes to the lungs via pulmonary trunk by ventricular systole, for oxygenation of blood by passing through pulmonary valve.
SYSTEMIC CIRCULATION
In systemic circulation, following events take place.
LEFT ATRIAL SYSTOLE
When oxygenated blood comes into left atrium, then left atrial sytole causes blood to enter left ventricle through bicuspid valve
LEFT VENTRICULAR SYSTOLE
When blood reaches here it sends into aorta through aortic valve to provide blood to body systems.
CARDIAC OUTPUT
The blood volume pump per minute by left ventricle into the systemic circulation
HEART BEAT
The contraction of heart chambers are known heart beat which are regular, rhythmic.
Ventricular systole is LUB
Ventricular diastole is DUB
TIME FOR HEART BEAT
0.8 sec is time for one heart beat.
CONDUCTING SYSTEM OF HEART
It consists of
1.AV-NODE
2.SA-NODE
3)AV-BUNDLE
4) PURKINJI FIBERS.
1. SA-NODE
SA NODE found near upper end of superior vena cava in RT. atrium
PARTS
1. Specialized cardiac Muscles.
2. Autonomic Nerve endings.
FUNCTIONS
It Initiates the contraction of heart chambers through impulses & also transmit to AV node.
2. AV- NODE
It is found in lower end of RT. Atrium. Structurally it is smilar to SA-NODE
FUNCTION
It transmit nerve impulses to ventricles for contraction rhythmically.
3. AV-BUNDLE
AV BUNDLE are the fibers originate from AV node. The bundle divided into Right AV bundle, Left AV bundle
FUNCTION
It transmit nerve impulses to ventricles.
4. PURKINJI FIBERS
AV bundles red divided into small fibres which penetrate the ventricle wall also known as purkinji fibers / Bundle of His small thin fibers.
LEUKEMIA
DEFINATION
“The malignant disorder of increase number of abnormal leucocytes in blood.”
CAUSE
The cause of leukemia is unknown.
FACTORS
Factors associated with leukemia are

• Ionizing Radiation
• Cytotoxic drugs.
• Retroviruses.
• Genetic

EFFECTS OF DISEASE

• In result of leukemia, normal leucocytes counts become less.
• This is progressive, and fatal condition which leads to heamorrhage or infection

THALASSEMIA
DEFINITION
“Genetically impaired globin chains formation leads to impaired or defected formation of hemoglobin.”
GENETIC DISEASE
Thalassemia is a genetic disorder, it may be
1. Hetrozygous /Mild thalassemia:
2. Homozygous.
TYPE
BETA – Thalassemia
α – Thalassemia
BETA-THALASSEMIA
When globin chain is impaired or defected. It is most common one.
ALPHA-THALASSEMIA
when α-thalassemia globin chain of (HB) hemoglobin is defected.
KINDS OF THALASSEMIA
THALASSEMIA MINOR
When thalassemia is of heterozygous type with mild anemia.
THALASSEMIA MAJOR
When thalassemia is of homozygous type with profound hypochromic anemia. It is more common in children & results with enlargement of kidney.
REMEDY
The only remedy is transfusion of blood at regular intervals.
CVD CARDIOVASCULAR DISEASE
Diseases of heart, blood vessels and blood circulation are generally term as CVD.
ATHEROSCLEROSIS
The disease of arterial wall with lose of elasticity, thickness of inner wall causing narrowing of lumen, results in impairing of blood flow.
ATHEROMATOUS PLAQUES
The narrowing is due to formation of fatty lesions called atheromatous plaque in inner lining of arteries.
COMPONENTS OF PLAQUE
These plaques consist of

• LDL-LOW DENSITY LIPO PROTEINS
• DECAYING MUSCLES CELLS
• FIBROUS TISSUE
• PLATELETES
• CLUMP OF BLOOD

CAUSES
Smoking, Hypertension, Obesity, Diabetes (Severe), family history of arterial disease
EFFECTS
Atherosclerosis produces no symptoms until the damage to artery is so severe that it restricts blood flow.
ANGINA PECTORIS
If blood flow to heart muscles is restricted causes (cell damage) necrosis called angina pectoris. Pain in chest, arm, or jaws usually during exercise.
THROMBUS FORMATION
The formation of blood clot with in the intact blood vessel initiated by atheromatous plaque.
REASON FOR THROMBUS FORMATION
Due to formation athromatous plaque loss of elasticity, intact blood vessel get destroyed, blood from vessel wall comes out & later change to blood clot and blocks the lumen of small arteries.
RESULT OF THROMBUS FORMATION
Initially thrombus block the lumen partially result in decrease blood flow to organs & leading to impairment of physiology of organs. Later on, thrombus blocks the lumen completely so due to complete loss of blood supply, cells damage occur.
CORONARY THROMBOSIS
Type of thrombosis when narrowing of lumen occurs in coronary blood vessels due to formation of clot.
EFFECT
Occulsion of coronary atery causes myocardial infarction and heart attack.
HEAMORRHAGE
The escaping of blood from intact blood vessels.
STROKE
Most dangerous type of heamorrhage is that of brain which results in paralysis or strokes.
HAEMATOMA
The accumalation of blood in interstitial spaces known as haematoma.
This will lead to edema.
STROKE
DEFINITION
The damage to the part of brain caused by, restriction in blood supply or leakage of blood outside the vessels.
CHARACTERISTICS
Impairment of sensation, movement & function controlled by damage part of brain.
CAUSES

• Hypertension
• Atherosclerosis

HEMIPLEGIA
Damage to any, one cerebral hemisphere can cause weakness or paralyses of one side of body called hemiplegia
PRECAUTIONARY MEASURES
Blood pressure should be with in normal range through proper diet. Salt should be used in less quantities exercise should be the regular habit. Smoking must be avoided. Person life should be free of worries.
BLOOD VESSELS
DEFINITION
“The closed vessels or tubes through which transporting medium or blood circulate with in body called “blood vessels”.
TYPES OF BLOOD VESSELS
1. Arteries.
2. Capillaries.
3. Veins.
ARTERIES
DEFINITION
Thick walled blood vessels which carry blood from heart to the organs of body.
LAYERS
It consists of three layers.
1. Tunica Externa/ Adventitia
2. Tunica Media
3. Tunica Intima
1-TUNICA EXTERNA
It is thin but tough layer, having abundant amount of collagen fibers. It is outer most layer.
2-TUNICA MEDIA
The middle layer has smooth muscle fibers & elastin fibers. It is the thickest layer.
3-TUNICA INTIMA
It consists of squamous endothelium.
LUMEN
Thick walled vessels & having smaller lumen than that of veins except arteries of brain & related to cranium having large lumen.
SEMILUNAR VALVES
They are not present in arteries.
BRANCHES – DIVISIONS
Aorta divides into large arteries, large arteries into smaller arteries, smaller arteries into arterioles, then they give rise to capillary.
At arteriole level, small sphincters are present which are known as PRE-CAPILLARY SPHINCTER.
SPHINCTER
FUNCTION
They are for regulating the diastolic pressure.
CHARACTERSTICS

• Arteries are elastic so during systolic pressure, they do not rupture and dilate.
• During ceasement/ stopage of systolic pressure of heart, arteries contract & supply even flow of blood.
• The arteries carry oxygenated blood except pulmonary arteries.

VEINS
DEFINITION
The thin walled blood vessels that drian blood from body parts/organs into heart called veins.
LAYERS
Tunica Externa
Tunica Media
Tunica Intima
1. TUNICA EXTERNA
Thickest layer in veins. It contains collagen, elastin and smooth muscles cells.
2. TUNICA MEDIA
Not thicker as that of arteries. Elastic tissues and small smooth muscle.
3. TUNICA INTIMA
Contains endothelial cells layer.
LUMEN
It has large lumen and thin wall.
SEMILUNAR VALVES
They are present in veins to prevent back flow of blood in the influence of gravity.
TRIBUTARIES
Veninules -> small veins -> large veins -> vena cava.
BLOOD PRESSURE
In veins blood pressure is low and are non pulsatile.
CHARACTERISTICS
The blood flows slowly and smoothly in veins. Veins are superficial and collapse when empty.
CAPILARIES
The intimate microscopic closed channels of both arterial & veinous interconnected network is called capillaries.
DIAMETER
Capillaries are extremely narrow in diameter of about 7-10 μ.
LAYERS
Capillaries are thin walled vessels & contains single layer of endothelium which offers small resistance in transport of material across the capillary wall.
FUNCTION
Through diffusion and active transport of oxygen is transported to tissues & CO2 to capillaries. Nitrogenous waste is filtered through the capillaries into excretory tubules.
BLUE BABIES (CYANOSIS)
Blue baby is a layman terminology. In medical science it is known as cyanosis.
DEFINITION
The term cyanosis” means the blueish discolouration of the skin & mucous membrane due to excessive cone of reduced (deoxygenated haemoglobin) in the blood & it appears when reduced Hb conc in capillaries is more than 5 gm/dl of blood. The reduced Hb has an intense dark blue purple colour that is transmitted through the skin.
MOST COMMON CAUSE OF CYANOSIS
Although there are various other causes of cyanosis but the most common cause is CONGENITAL CYANOTIC HEART DISEASE.
BASIC CAUSE OF CYANOSIS
In congenital heart diseases, there is an abnormal connection b/w right and left side of heart, which permits the large amount of unoxygenated venous blood to bypass the pulmonary capillaries & dilute the oxygenated blood in systemic arteries i.e RIGHT TO LEFT SHUNT, which results in cyanosis.
SOME EXAMPLES OF CONGENITAL HEART DISEASES

• Some congenital heart diseases which are responsible for the abnormal connection between right and left sides of heart are as follows.
• ATRIAL SEPTUM DEFECT (ASD)
• VENTRICULAR SETPUM DEFECT (VSD)
• PERSISTANT DUCTUS ARTEROSUS
• In all these conditions, blood begins to flow from the aorta (left side) into pulmonary arteries (right side) & the people donot show cyanosis until late in life when heart fails or lungs become congested.

TETRALOGY OF FALLOT (RIGHT –TO-LEFT SHUNT)
It is the most common cause of cyanosis or blue baby in which aorta originates from right ventricles rather than left & receives deoxygenated blood.

Circulatory System

HUMAN HEART INTRODUCTION
Heart, the most powerful organ in the circulatory system is conical, hollow & muscular organ, situated in middle mediastinum.
POSITION OF HEART
Heart lies in the thoracic cavity between the lungs slightly towards left, enclosed with in ribcage with the sternum in front & vertebral column behind.
SIZE & WEIGHT
The heart measures about 3 ½ Inches & weighs about 300 gm in males & 250 gm in females.
MAIN FUNCTION OF HEART
Heart works continuously like a muscular pump & pumps the blood to various parts of the body to meet their nutritive requirements.
COVERING OF HEART PERICARDIUM
Heart is surrounded by a double layered pericarcdium. The outer layer is called Fibrous pericardium & inner layer is called as serous pericardium.
PERICARDIAL FLUID
Fluid is secreted in b/w the two layers of pericardium which is known as pericardial fluid.
FUNCTION
Pericardial fluid acts as LUBRICANT & reduces friction b/w heart walls & surrounding tissues during beating of heart.
STRUCTURE OF HEART
Human heart consists of four chambers.
CHAMBERS OF HEART
1. RIGHT ATRIUM
Right Atrium is the right upper chamber of heart & acts as thin walled low pressure pump.
OPENINGS (INLETS) OF RIGHT ATRIUM
1. Superior Vena Cava
2. Anfenior Vena Cava
3. Coronary Sinus
FUNCTION
It receives venous blood from the whole body & pump it to the right ventricle through the right atrioventricular (tricuspid opening) valve.
2. LEFT ATRIUM
Left atrium is upper triangular chamber which is present posteriorly. It also acts as low pressure pump.
OPENINGS (INLETS) OF LEFT ATRIUM
Two pairs of pulmonary veins.
FUNCTION
It receives oxygenated blood from the lungs through 4 pulmonary veins and pumps it to the left ventricle through the left atrioventricular orifice (mitral or bicuspid).
3. RIGHT VENTRICLE
Right ventricle is the right lower chamber of heart, which is triangular in shape.
OPENINGS OF RIGHT VENTRICLE

• Tricuspids valve
• Pulmonary Aorta through pulmonary valve.

THICKNESS OF WALL

• The wall of right ventricle is thinner than that of left ventricle in a ratio of 1:3

SIZE OF CAVITY
Cavity of right ventricle is broader than left because of thin muscular walls, and both of these features are due to the fact that right ventricle has to pump the blood into lungs only against low pressure system (i.e. pulmonary circulation).
FUNCTION
Right ventricle receives deoxygenated blood from right Atrium and pumps it to the lungs through pulmonary aorta for oxygenation.
4. LEFT VENTRICLE
Left ventricle is the most thick walled chamber and forms the apex of heart.
OPENING OF LEFT VENTRICLE

• Bicuspid or Mitral valve
• Systemic Aorta through aortic valve.

THICKNESS OF WALL
The walls of left ventricle are 3 times thicker than those of right ventricle. Blood pressure is 6 times high.
SIZE OF CAVITY
The cavity of left ventricle is narrower than the right ventricle because of more muscular walls. It is due to the fact that left ventricle has to pump the blood to the entire body against high pressure system (Systemic Circulation).
FUNCTION
It receives oxygenated blood from left atrium & pumps it into the aorta.
INTERNAL STRUCTURE OF VENTRLES
Interior of ventricles show two parts
1. Rough in flowing part
2. Smooth out flowing part
1. ROUGH PART
TRABECULAE CARNEAE
Inflowing part of each ventricle is rough due to presence of muscular ridges called as Trabeculae carneae.
2. SMOOTH PART
Out flowing part of each ventricle is smooth which gives origin to pulmonary trunk in right ventricle & Ascending Aorta in left ventricle.
PAPILLARY MUSCLES
Papillary muscles are the type of Trabeculae carneae being attached by their bases to ventricular walls, & their apices are connected to, the cusps of valves through chorda tendinae.
CHORDA TENDINAE:
These are delicate fibrous chords, which connect the papillary muscles to the cusps of Atriovertritcular valves.
FUNCTION
Chorda Tendinae don’t left the valves open back into the atria when the ventricles contract.
SEPTUM OF HEART
1. INTERATRIAL SEPTUM
Internally, the right & left atria are separated by a vertical membranous septum called as Interatrial septum.
2. INTERVENTRICULAR SEPTUM:
The right & left verticals are also separated by a thick muscular septum called as Interventricular septum.
3. ATRIOVENTRICULAR SEPTUM
Atria lie above & behind the ventricles & are separated from ventricles by Atrioven-tricular septum.
HEART VALVES
Heart possesses two types of valves, which regulate the flow of blood with in the heart.
TYPES OF HEART VALVES
1. Atrioventricular valves -> Bicuspid, Tricuspid
2. Semilunar vlaves -> Aortic valve, Pulmonary valve
1. ATRIOVENTRICULAR VALVES
INTRODUCTION
Valves, which are present in b/w the Atria & ventricles are called Atrioventricular valves.
TYPES OF ATRIOVENTRICULAR VALVES
They are of two types.
1. Bicuspid or Mitral
2. Tricuspid.
1. BICUSPID OR MITRAL VALVE
Blood flows from left Atrium to the left ventricle through left atrioventricular on orifice, which is guarded by bicuspid or Mitral valves.
CUSPS
It has tow (2) cusps so it is called as bicuspid.
2.TRICUSPID VALVE
Blood flows from right Atrium to the Right ventricle through right Atrioventricular orifice, which is guarded by Tricuspid.
CUSPS
It has 3 cusps so it is called as TRICUSPID.
2. SEMILUNAR VALVES
This is the second category of heart valves, which guard the emergence of pulmonary & systemic Aorta.
TYPES OF SEMILUNAR VALVES
It has Two Types:
1. Aortic Valve
2. Pulmonary Valve
1. AORTIC VALVE
This valve guards the Aortic orifice in left ventricle
CUSPS
It consists of 3 Semilunar cusps.
2. PULMONARY VALVE
This valve guards the pulmonary orifice in right ventricle.
CUSPS
It also consists of 3 semi lunar cusps.
FUNCTIONS OF VALVES
Heart valves maintain unidirectional flow of the blood & prevents its regurgitation in the opposite direction

Botony

DIFFUSION The movement of ions or molecules from the region of higher concentration to the region of lower concentration is known as diffusion.
EXAMPLES
1. If a bottle of perfume is opened in a corner of a room, it can be smelt in the entire room.
2. Leakage of gas pipes can be smelt from a farther point.
3. If we drop a KMNO4 crystal in clean water, then after sometime the crystals will dissolve and colour of water changes from colorless to purple.
FACTORS ON WHICH RATE OF DIFFUSION DEPENDS
1-SIZE
Small molecules move faster than larger ones.
2-TEMPERATURE
Rate of diffusion will be high at high temperatures.
3-CONCENTRATION GRADIENT
Greater the difference in concentration and shorter the distance between two regions, greater will be the rate of diffusion.
FACILITATED DIFFUSION
Diffusion of the substances across the cell membrane through the specific carrier proteins is known as facilitated diffusion. These membrane transport proteins are channel proteins, receptors, cell pumps or carriers, made up of usually proteins and don’t require energy for transport.
PASSIVE TRANSPORT
Movement of substances in and out of the cell, caused by simple kinetic motion of molecules, doesn’t require energy of ATP is known as passive transport, e.g. Simple diffusion and facilitated diffusion.
OSMOSIS
The movement of water molecules from the region of higher concentration to the region of lower concentration through a semi-permeable membrane, is known as osmosis.
TYPES OF OSMOSIS
A- ENDOSMOSIS
The movement of water molecules into the cell, when it is placed in hypotonic solution is called as Endosmosis.
B- EXOMOSIS
The movement of water molecules out of the cell when the cell is placed in a hypertonic solution.
ACTIVE TRANSPORT
The movement of ions or molecules across the cell membrane against the concentration gradient i.e. from lower concentration to higher concentration with the help of specific transport proteins in the cell membrane, at the expense of cell’s metabolic energy – ATP is called active transport.
EXAMPLES
1. Sodium-Potassium pump in nerve cells which pump Na+ out of the nerve cell, and K+ into the cell against the concentration gradient.
2. Cells lining the intestine can transport glucose actively from a lower concentration in the intestinal contents to higher concentration in blood.
3. In plants phloem loading is an ex. Of active transport.
IMBIBITIONS
Adsorption of water and swelling up of hydrophilic (water loving) substances is known as imbibitions.
HYDROPHILIC SUBSTANCES
Those which have great affinity for water are hydrophilic e.g. starch, gum, protoplasm, cellulose, proteins, e.g. seeds swell up when placed in water.

• Wrapping up of wooden framework during rainy seasons.
• Dead plant cells are hydrophilic colloids.
• The chemical potential of water is a quantitative expression of the free energy associated with the water.
• UNIT: Joules/mole
• This term has been replaced by water potential

WATER POTENTIAL (PSI)
It is the difference between the fee energy of water molecules in pure water and energy of water in any other system, or solution. Water potential is a relative quantity, depends upon gravity and pressure.
Q = Q* + f (concentration) + f (pressure) + f (gravity)
Β* is standard water potential or pure water potential of valve O Mpa.
Unit : Megapascal’s – MPa
(1 Mpa = 9.87 atmospheres)
USES
The direction of water flow across cell membrane can be determined. It is a measure of water status of the plant.
OSMOTIC PRESSURE
The pressure exerted upon a solution to keep it in equilibrium with pure water when the two are separated by a semi permeable membrane is known as Osmotic pressure.
It prevents the process of osmosis.
OSMOTIC POTENTIAL
The tendency of a soln to diffuse into another, when two solutions of different concentrations are separated by a differentially permeable membrane.

• It is represented by βs for pure water βs = 0
• The βs decrenses as the osmotic concentration increases.
• Osmotic concentration is the number of osmotic-ally active particle per unit volume.
• Osmotic potential has been replaced by solute potential.
• The concentration of solute particles in a solution is know as solute potential βs. It value is always negative.

PRESSURE POTENTIAL ΒP
When a cell is placed in pure water or in aqueous solution with higher water potential than the cell sap water follows into the vacuole by endosmosis thru cell membrane and tonoplast. Due to this inflow of water, the tension developed by the cell wall causes an internal hydrostatic pressure to develop, which is called as pressure potential.
Β = βs + βp or Qp = Q – Qs
In turgid cells βp is equal and opposite to βs
TURGID CELL
When the cell is fully stretched with maximum pressure potential, the water cannot flow into it. This condition is called turgidity and the cell is turgid.
PLASMOLYSIS
If a cell is placed in a hypertonic solution, which has more negative solute and water potentials then water will come out of the cell, by exosmosis and protoplasm starts separating from cell wall leaving a gap between cell wall and cell membrane. This withdrawal of protoplasm from cell wall is known as plasmolysis.
The point where protoplasm just starts separating from cell wall is known as “Incipient plasmolysis” when it is completely separated, full plasmolysis occurs.
In plasmolysis cell βp = 0 therefore βw = βs
DEPLASMOLYSIS
When a cell is placed is a hypotonic solution or pure water, there will be an inflow of water by endosmosis. Protoplasm starts expanding and presses cell wall due to which pressure potential develops and water potential becomes less negative. This swelling of cell is known as deplasmolysis.
WATER AND MINERALS UPTAKE BY ROOTS
1. Absorption of water and mineral salts takes place through root system.
2. Roots are provided with enormous number of tiny root hairs.
3. These root hairs are more in number in tap root system.
4. Roots hairs are out growths of epidermal cells.
5. Roots hairs increase the surface area for absorption.
6. Most of the absorption takes place at root tips.
7. From hairs and epidermal cells water flows thru cortex, endodermis, pericycle and them enters xylem.
There are 3 pathways for water to enter xylem.
A- CELLULAR PATHWAY
In this route water flows through cell to cell. Water enters the root hairs or epidermal cells down a concentration gradient: it flows through cell wall and cell membrane and enters the adjacent cell from where water may again flow towards the deeper cells by osmosis.
B- SYMPLAST PATHWAY
Cytoplasm of the cortical cells are interconnected by small pores in the cell wall known as plasmodesmata.
These pores provide another way of transporting water and solutes across the plasma membrane at root hairs.
C- APOPLAST PATHWAY
The cell walls of cortical and epidermal cells are hydrophilic and form a continuous matrix. Soil solution flows freely through these hydrophilic walls. The movement of soil soln.through extra cellular pathway provided by continuous matrix of cell walls is known as “Apoplast pathway”.
Simplast and apoplast usually both occur concurrently.
Endodermis forms a waxy barriers against the flow of water and salts known as “casparion strip”. So, water cannot enter endodermis via apoplast pathway. Symplast is the only way to cross the barrier. Endodermal cells actively transport salts to pericycle resulting in high osmotic potential which causes inflow of water by osmosis salts. Form pericycle water flows in to xylem via both symplast and apoplast pathways.
TRANSPIRATION
The loss of water in the form of vapours from aerial parts of the plant is called transpiration.
TYPES OF TRANSPIRATION
Following are the three types of transpiration.
A- STOMATAL TRANSPIRATION
It is a type of transpiration in which the water vapours escape through the stomata. 90% of the total transpiration occur thru this method. In isobilateral leaves the stomata are present in both upper and lower epidermis e.g. lily and maize leaves. In dorsiventral leaves, the stomata are only confined to lower epidermis e.g. Brassica and sunflower.
B- CUTICULAR TRANSPIRATION
The loss of water in the form of vapours through the cuticle of leaves is called Cuticular Transpiration. About 5-7% of total transpiration takes place thru this route cuticle is a waxy layer which covers the leaves and tis is not completely impermeable to water.
C- LENTICULAR TRANSPIRATION
It is the loss of water vapours through lenticles present in the stems of dicot plants. Lecticles are aerating pores present in the bark formed as a result of secondary growth. It accounts for only 1-2% of total transpiration.
MECHANISM OF STOMATAL RESPIRATION
STRUCTURE OF STOMATA
Stomata are microscopic pores present in the epidermis of leaves and herbaceous stems. Number of stomata are variable in different leaves and depend upon the availability of water and climate of the region. Each stomata is surrounded by 2 specialized epidermal cells, as guard cells, they are bean shaped or kidney shaped and unlike other epidermal cells, they contain chlorophyll, hence perform photo-synthesis. The inner wall of guard cell is thick while the outer wall is thin and elastic. This structural difference is important for opening and closing of stomata.
STAGES OF TRANSPIRATION
There are two processes involved in stomata transpiration.
+ EVAPORATION
In the first step, water evaporates from the wet surfaces of turgid mesophyll cells and collected in the intercellular air spaces.
+ DIFFUSION
In this stage water vapours diffuse out from intercellular spaces where they are in higher concentration to the outer atmosphere where they are in lower concentration through the stomata.
MECHANISM OF OPENING AND CLOSING OF STOMATA
The opening and closing of stomata depends upon the turgidity of guard cells, which is due to increase or decrease in the osmotic potential of the guard cells. When water enters the guard cells by osmosis, they swell up. Since their outer walls are thin and elastic, they stretch and bulge out. The inner thick walls cannot stretch and so arch in and become crescent shaped thus the gap between the two guard cells widens, opening the stomata when the guard cell lose water, they become flaccid and the inner wall of two guard cells meet each other, closing the stomata.
Generally the stomata remain open during day time and close at night. Thus light appears as the primary factor which control the opening and closing of stomata.
FACTORS REGULATING OPENING AND CLOSING OF STOMATA
There are two main factors which greatly influence the opening and closing of stomata these are
1- LIGHT
In the presence of light, chlorophyll containing guard cells synthesize sugars which is turn increase the osmotic potential of guard cells. This increase Qs results in endosmosis and ultimately to turgidity. While in darkness these guard cells consume carbohydrates (sugars) by respiration for energy production or transported to other neighbouring cells for respiration and different purposes. This decreases the osmotic potential of guard cells leading to flaccidity because of exomosis of water.
2- CONCENTRATION OF K+ IONS
Turgidity of guard cells of many plants is regulated by K+ ion concentration. During daytime, guard cells actively transport K+ions into them from neighbouring cells. Accumulation of K+ ions lowers the water potential of guard cells. This causes on inflow of water by endosmosis from epidermal cells. During night when they lose K+ ion, water potential increases. Water flows out of the guard cells by exosmosis causing them to become flaccid which result in closure of pore.
FACTORS AFFECTING TRANSPIRATION
Rate of transpiration is very important for a plant because transpiration stream is necessary to distribute dissolved mineral salts through out the plants. Water is transported to photosynthesizing cells of leaves. Transpiration is also very important as it cools the plant. This is especially important in higher temperatures. If the rate of transpiration is very high, there would be much loss of water from the plant. So at high temperatures the stomata almost close and reduction in the rate of transpiration is effected. This stops witting of the leaves and of herbaceous stems of plants.
Following are some important factors which affect the rate of transpiration.
1. LIGHT
Light affects the transpiration in two ways:
a. Light regulates the opening and closing of stomata. During sunshine the stomata are open, losing water vapours thus rate of transpiration is high and during night, the stomata are closed, so the rate of transpiration is low.
b. Greater intensity of light, increases the temperature and warms the leaf, so leaves lose heat by evaporating water molecules to cool themselves.
2. TEMPERATURE
Plants transpire more rapidly at higher temperature than at low. Rise in temperature has two effects:
i. It increases kinetic energy of water molecules, which results in rapid evaporation of water and decreases the rate of transpiration.
ii. High temperature reduces the humidity of surrounding air. Due to this, evaporation from surfaces of mesophyll cells increase and hence rate of transpiration.
3. WIND
The air in motion is called wind. The area around the stomata is saturated with water vapours due to transpiration. During high velocity wind the area around leaves is quickly replaced by fresh drier air which increases diffusion of water molecules from air spaces to outside atmosphere and increases the rate of transpiration.
When air is still, the rate of diffusion of water molecules is reduced and the rate of transpiration is also reduced.
4. HUMIDITY
When air is dry, the rate of diffusion of water molecules, from the surfaces of mesophyll cells, air spaces and through stomata, to outside the leaf increases. So more water is lost, increasing the rate of transpiration.
In humid air, the diffusion of water molecules is reduced. This decreases the rate of transpiration.
5. SOIL WATER
A plant can’t continue to transpire rapidly if its moisture loss is not made up by absorption of fresh supplies of water from the soil. When absorption of water by roots fails to keep up with rate of transpiration, loss of turgor occurs and wilting of leaf takes place.
DISADVANTAGES OF TRANSPIRATION
1. Transpiration is said to be necessary evil because it is an inevitable, but potentially harmful, consequence of the existence of wet cell surfaces from which evaporation occurs.
2. High rate of transpiration causes water deficiency and thus the excessive transpiration leads to wilting and death of plants.
3. There is good evidence that even mild water deficiency results in reduced growth rate of plants.
4. Excessive transpiration effects the protein synthesis, sugar synthesis and other metabolic activities of plants.
ADVANTAGES OF TRANSPIRATION
1. Water is conducted in most parts of plants due to transpiration pull or ascent of sap.
2. It causes absorption of water and minerals from the soil.
3. Minerals dissolved in water are conducted throughout the plant body by transpiration stream.
4. Evaporation of water from the exposed surface of cells of leaves has cooling effect on plant.
5. Excess water is removed.
6. Wet surface of leaves allow gaseous exchange.
GUTTATION
It is the loss of water in the form of droplets from the ends of large leaf-veins. It take place through special openings called hydathodes.
DIFFERENCES BETWEEN TRANSPIRATION AND GUTTATION
TRANSPIRATION
Water escapes in the form of wapours.
Escape water is pure and does not contain solutes.
It takes place through stomata, and cuticle.
It is regulated by stomata.
Normally takes place in light
GUTTATION
Water escapes as liquid.
Escaped water contain solutes.
It takes place through hydathodes and end of veins.
It is not a regulated process.
Takes place at night.
TRANSLOCATION OF ORGANIC SOLUTES
Transport of organic products of photosynthesis, like sugars from mature leaves to the growing and storage organs in plants is called translocation. This movement of photo assimilates and other organic materials takes place via the phloem and is therefore called “Phloem Translocation.”
The phloem is generally found on the outer side of xylem and constitutes the bark. The cells of phloem that take part in phloem translocation are called sieve elements. Phloem tissue also contains companion cells, parenchyma cells, fibres like sclereids latex containing cells. But only sieve tube cells are directly involved in tansport of organic solutes.
SOURCE TO SINK MOVEMENT
The translocation of photosynthesis always takes place from source to sink tissues, therefore, the phloem transport is also referred as “source to sink movement.”
SOURCE
The part o plant which forms the sugars or photoynthates is known as source. For example Mature Leaves.
SINK
Sinks are the areas of active metabolism or storage of food e.g: Roots, Tubers developing fruits, immature leaves, growing tips of roots and shoots. Some source and sinks are interconvertible during the process of development of plants. For example: developing and mature leaves, developing and germinating seeds, root of sugar beets etc.
MUNCH HYPOTHESIS (MECHANISM OF PHLOEM TRANSLOCATION)
Phloem translocation is mainly explained by a theory called the “Pressure flow hypothesis” proposed by Ernest munch in 1930 which explains the steps involved in the movement of photosynthates from mesophyll chloroplasts to the sieve elements of phloem of mature leaves.
STEPS
The following steps explain flow theory:
1. The glucose formed during photosynthesis in mesophyll cells, is used in respiration or converted into non-reducing sugar i.e. sucrose.
2. the sucrose is actively transported to bundle sheath cells and then to companion cell of the nearest smallest vein in the leaf. This is called “short distance transport” because solutes cover only a distance of two or three cells.
3. Sucrose diffuse into sieve tube cell or sieve elements by symplast pathway or apoplast pathway. This is called phloem loading, this raises the conc. of sugars in sieve elements, which causes osmosis of water from nearby xylem in the leaf. It causes an increase in the hydrostatic pressure or tugor pressure.
4. The increase hydrostatic pressure moves the sucrose and other substances in the sieve tube cells, and moves to sinks. The photo-assimilates (sugars etc) can be moved a long distance i.e. of several meters, therefore this is known as “Long distance transport.”
5. In the sink tissues, present at the other end of pathway, sugars are delivered by phloem by an active process called “Phloem Unloading.” It produces a low osmotic pressure in sieve elements of sink, as a result of this water potential begins to rise in the phloem and causes an exosmosis of water molecules from the sieve tubes. This causes a decrease in turgor pressure of the sieve tubes (phloem).
6. The presence of sieve plates in the sieve elements greatly increases the resistance along the pathway and results in the generation and maintenance of a substantial pressure gradient in the sieve elements between source and sink. The sieve elements contents are physically pushed along the traslocation pathway by bulk flow, much like water flowing through a garden house.
SIGNIFICANCE OF TRANSLOCATION
1. Food can be formed or stored as in sugar beet’s root or stem of sugar cane.
2. Sucrose is transported to sink where it is converted to glucose and used as energy.
3. Productivity of crop can be increased by accumulation of photo-synthates in edible sink tissues like cereal grains, pulses, ground nuts etc.
4. Fruit is forme by this process e.g. Apples, Mango etc.
ASCENT OF SAP
The upward movement of water and dissolved mineral salts from the roots to the leaves agains the downward pull of gravity is known as “Ascent of Sap.”
PATH OF MOVEMENT
The distance traveled by water is small and easy in plans like herbs and shrubs and longest in tall trees like pinus, red wood, eucalyptus etc. For transport different tissues of xylem is used for conduction of water in different plants. These are open ended cells called “Vessels” and porous cells called “tracheids” (Fig. From book).
A. VESSELS
1. These are thick walled tube like structures which extend through several feet of xylem tissue.
2. They range in diameter from 20μm to 70μm.
3. Their walls are lignified and perforated by pits. At the pit, cell wall is only made up of cellulose. Pits of adjacent cells match up with each other, so that their cavities are interconnected.
4. Xylem vessels arise from cylindrical cells, which placed end to end. They die at maturity forming a continuous duct, providing a channel for long-distance transport of water.
5. Rate of flow of water is 10 times faster than tracheids.
OCCURANCE
VESSELS are mostly found in Angiospermic plants.
B. TRACHEIDS
1. These are individual cells about 30μm in diameter. They are several mm long and tapered.
2. Like vessels, they are also dead, made up of thick lignified walls.
3. Their walls are perforated by small pits, which are of two types, simple and bordered.
4. The Tracheids are connected by pits and forming a long channel for conduction of water.
OCCURANCE
In Ferns and Conifers.
MECHANISM OF ASCENT OF SAP
Water and dissolved mineral salts present in xylem, flow in upward direction at the rate of 15m/hour. Xylem sap ascends because of two reasons:
1. Push from below – Root Pressure Theory
2. Pull from above – Dixon’s Theory
1. ROOT PRESSURE THEORY
According to Stephen Hales:
“The force which is responsible for the upward movement of water molecules in xylem is by the pushing effect from below (i.e. roots) and is known as “Root Pressure.” Root Pressure is created by active secretion of sals and other solutes from the other cells into xylem sap.
This lowers the water potential of xylem sap. Water enters by osmosis, thus increasing the level of sap. Water also take apoplast or symplast pathway to enter the xylem cells, this increased level causes a pressure effect in xylem and pushes the water upwards.
OBJECTIONS/FAILURE OF THEORY
1. This force is unable to push water in tall plants.
2. It is seasonal.
3. Completely absent from Cycads and Conifers, so how they transfer water.
4. When a cut shoot is placed in water, the water rises in shoots although roots are absent.
5. It is also present in plant which donot have well developed root system.
2. TRANSPIRATION PULL (DIXON’S THEORY) OR ADHESION-COHESION-TENSION THEORY
Dixon and Jolly proposed this theory for ascent of sap. It provides a reasonable explanation of flow of water and minerals from the roots to leaves of plants. It depends on:
ADHESION
Adhesion is the sticking together of molecules of different kinds. Water molecules adhere to the cell walls of xylem cells, so that the column of water in xylem tissue doesn’t break. The cellulose of cell wall has great affinity for water, which helps in the process.
COHESION
Cohesion is the attraction among molecules of same kind, which holds water molecules together, forming a solid chain-like column within the xylem tubes. Extensive hydrogen bonding in water gives rise to property of cohesion. The molecules of water in xylem tube form a continuous column.
TRANSPIRATION PULL
The loss of water from the aerial parts of the plant especially through stomata of leaves is called transpiration.
During daytime the leaf after absorbing sunlight, raising its temperature starts transpiration. When a leaf transpires, the water potential of its mesophyll cells drop. This drop causes water to move by osmosis from the xylem cells of leaf into dehydrating mesophyll cells.
The water molecules leaving the xylem are attached to other water molecules of tube by H-bonding.
Therefore, when one water molecules moves up the xylem, the process continues all the way to the root, where water is pulled from the xylem cells, i.e. tracheids or vessels.
Due to this pulling force or transpiration pull, water in xylem is placed under tension which is transmitted to root through vessels. Tension is due to H-bonding and strong cohesive forces between water molecules, and is strong enough to pull water upto 200 metres or even more.
ASCENT OF SAP IS SOLAR POWERED
To transport water over a long distance, plants do not use their metabolic energy or ATPs. It is done only by forces like adhesion, cohesion, evaporation and presence of sunlight. Thus ascent of sap is “Solar Powered.”
SIGNIFICANCE OF ASCENT OF SAP

• Water can be transported to the different parts of the plant.
• Transpiration is regulated.
• Food is formed in presence of water.
• Photosynthesis requires water.
• Salts and minerals are also absorbed along water by roots.

Gaseous Exchange

RESPIRATORY ORGANS OF COCKROACH TRACHEAL SYSTEM Cockroach has evolved a special type of invaginated respiratory system called Tracheal system, especially adopted for terrestrial mode of life and high metabolic rate of insects.
STRUCTURAL CONSTITUENTS OF TRACHEAL SYSTEM
1. TRACHEA
2. SPIRACLES
3. TRACHEOLES
1.TRACHEA
Tracheal system consists of number of internal tube called Trachea which are the connection between the spiracles and tracheal fluid.
2. SPIRACLES
Laterally, trachea open outside the body through minute, slit like pores called as spiracles.
There are 2 pairs of spiracles on lateral side of cockroach.
2 lie in thoracic segments and 8 in first abdominal segments.
3. TRACHEOLES
On the other side, trachea ramify throughout the body into fine branches or tracheols.
Tracheoles, finally end as blind, fluid filled fine branches which are attached with cells of tissue.
Both the trachea and tracheoles are lined internally by thin layer of cuticle.
MECHANISM OF RESPIRATION “INFLOW OF OXYGEN”
The cockroach takes in air directly from the atmosphere into the trachea through spiracles. This air diffuses directly into fluid filled tracheoles through which diffuses into the cells of tissues. Hence the blood vascular system of cockroach is devoid of haemoglobin.
OUTFLOW OF CARBONDIOXIDE
Removal of CO2 from cells of body is largely depended upon plasma of blood, which takes up CO2 for its ultimate removal through body surface via the cuticle.
RESPIRATORY SYSTEM OF FISH
MAIN RESPIRATORY ORGAN
In fish, main respiratory organs are “Gills”. They are out growth of pharynx and lie internally with in the body so that they are protected from mechanical injuries.
INTERNAL STRUCTURE OF GILLS
Each gill is highly vascularized structure. It is composed of
1. Filaments
2. Gill bar or Gill arch
3. Lamella
1. FILAMENTS
Each gill is composed of two rows of hundreds of filaments, which are arranged in V-shape.
2. GILL BAR OR GILL ARCH
Filaments are supported by a cartilage or a long curved bone the gill bar or gill arch.
3. LAMELLA
Lamella is a plate like structure which is formed by infolding of filaments. Lamella greatly increase the surface area of the gill. Each lamella is provided by a dense network of capillaries.
OPERCULUM (IN BONY FISHES)
Gills are covered on each side by gill cover called “operculum”
MECHANISM OF VENTILATION
In bony fishes, ventilation is brought about by combined effect of mouth and operculum.

• Water is drawn into the mouth. It passes over the gills through pharynx and ultimately exists at the back of operculum through open operculur valve.
• Water is moved over the gills in a continuous unidirectional flow by maintaining a lower pressure in operculur cavity than in buccopharynx cavity.

COUNTER CURRENT FLOW OF WATER AND BLOOD
Gaseous exchange is facilitated in gills due to counter current flow of H2O and blood.
In the capillaries of each lamella, blood flows in direction opposite to the movement of water across the gill. Thus the most highly oxygenated blood is brought to water that is just entering the gills and has even high O2 content than the blood. As the H2O flows over the gills, gradually loosing its oxygen to the blood, it encounter the blood that is also increasingly low in oxygen. In this way a gradient is establishment which encourages the oxygen to move from water to blood
IMPORTANCE
Counter current flow is very effective as it enables the fish to extract upto 80–90% of the oxygen from water that flows over the gills.
RESPIRATORY SYSTEM OF MAN
MAIN FUNCTION OF RESPIRATION
The main function of respiratory system is inflow of O2 from the atmosphere to the body and removal of CO2 from body to the atmosphere.
COMPONENTS OF RESPIRATORY SYSTEM
(1) PAIRED LUNGS
The respiratory (gas exchange) organs.
(2) AIR PASSAGE WAYS
Which conduct the air
(3) THORACIC CAVITY
Which lodges the lungs
(4) INTERCOSTAL MUSCLES AND DIAPHRAGM
Which decreases and increase the diameters of thoracic cavity
(5) RESPIRATORY CONTROL CENTRES
Areas in brain which control the respiration.
DETAILS OF COMPONENTS
+ THORACIC CAVITY
Paired lungs with in the pleural sacs are situated in the thoracic cavity. Separating the thoracic cavity from the abdominal cavity is a dome-shaped musculo-tendinuous partition called as Diaphragm.
BOUNDARIES OF CAVITY
Thoracic cavity is supported by bony cage (thoracic cage) which is made up of

• Sternum -> in front
• Vertebral column -> at the back
• 12 pairs of ribs -> on each side
• Ribs are supported by Intercostal muscles

FUNCTION
Increase in thoracic cavity diameter is responsible for inspiration. While decrease in diameter is responsible for expiration.
AIR PASSAGE WAYS
Air is drawn into the lungs by inter-connected system of branching ducts called as “Respiratory tract” or “Respiratory passage ways”
Air passage ways consists of
AIR CONDUCTING ZONE(which only conducts the air)
1. Nostrils
2. Nasal Cavity
3. Pharynx (nasopharynx and oropharynx)
4. Larynx
5. Trachea
6. Bronchi
7. Bronchioles (also called terminal Branchioles)
RESPIRATORY ZONE(Where gaseous exchange takes place)
8. Respiratory Bronchioles
9. Alveolar duct
10. Alveolar sacs or alveoli
GENERAL FUNCTIONS OF CONDUCTING AIR PASSAGES
1. Conduction of air from atmosphere to the lungs
2. Humidification of inhaled dry air.
3. Warming / cooling of air to body temp.
4. The injurious particles are entrapped by mucous and removed by ciliary movements.
5. Lymphoid tissues of pharynx provide immunological functions
6. Cartilages prevent the passages from collapse but are not present in Bronchioles which remains expanded by same pressure that expand the alveoli.
CONDUCTING ZONE
1. NASAL CAVITY
Atmospheric air enters the respiratory tract through a pair of openings called external nares (Nostrils), which lead separately into nasal cavity. Nasal cavity opens into naso pharynx through posterior nares (choanae).
Nasal cavity is lined internally by Pseudostratified columnar ciliated epithelium containing mucous secreting cells.
Hairs, sweat and sebaceous glands are also present.
SPECIALIZED FUNCTIONS

• Warming of air
• Humidification or moistening of air
• Filteration of air with the help of hairs
• All these together called as Air conditioning function of upper respiratory passages
• Olfaction ( sense of smell)

2. PHARYNX
Air enters from Nasal cavity into pharynx through internal nostrils. The openings of nostrils are guarded by soft palate. It is internally lined by Pseudostratified ciliated epithelium, mucous glands are also present.
FUNCTION
Pharynx is responsible for conduction of air as well as food
3. LARYNX (VOICE BOX)
Pharynx leads air into larynx through an opening called glottis. Glottis is guarded by flap of tissue called epiglottis. During swallowing, soft palate and epiglottis close the nostrils opening and glottis respectively so that food is prevented to go either into nasal cavity or glottis. Larynx, a small chamber consists of pair of vocal cords
FUNCTION
During speech, vocal cords move medially and their vibration produce sound
4. TRACHEA (WIND PIPE)
Larynx leads the air into a flexible air duct or trachea. It bears C-shaped tracheal cartilages which keep its lumen patent during inspiration. Its internal lining is pseudostratified columnar ciliated epithelium containing mucous secreting goblet cells.
FUNCTION
Conduction of air
Due to mucous and upward beating of cilia, any residues of dust and germs are pushed outside the trachea towards the pharynx.
5. BRONCHI
“At its lower end, trachea bifurcates into two smaller branches called Principle Bronchi↑ which leads the air into lung of its side. They are also supported by C-shaped cartilage rings upto the point where they enter the lungs”.
In all areas of trachea and bronchi, not occupied by cartilage plates, the walls are composed mainly of smooth muscles.
6. BRONCHIOLES
On entering the lungs, each bronchus divide repeatidly. As the bronchi become smaller, U-shaped bars of cartilage are replaced by irregular plates of cartilages. The smallest bronchi divide and give rise to Bronchioles (less than 1.5 mm in diameter).
7. TERMINAL BRONCHIOLES
Bronchioles divide and give rise to terminal bronchioles (less than 1 mm in diameter). Walls possess no cartilages and are almost entirely the smooth muscles. These are the smalled airways without alveoli.
RESPIRATORY ZONE
In this zone of respiratory tract, gaseous exchange between capillary blood and air takes place.
1. RESPIRATORY BRONCHIOLES
Terminal bronchioles show delicate outpouchings from their walls, which explains the name Respiratory Bronchioles (less than 0.5 mm in diameter). They bear the pulmonary alveoli.
2. ALVEOLAR DUCTS AND SACS
Each respiratory bronchioles terminates at a tiny hollow sac like alveolar duct that lead into tabular passages with numerous thin walled out pouchings called Alveolar sacs.
3. PULMONARY ALVEOLI
The alveolar sacs consists of several alveoli openings into a single chamber. Alveoli are the site of exchange of respiratory gases so they are considered as Respiratory surfaces of lungs. Each alveolus is surrounded by a network of blood capillaries.
INTERNAL STRUCTURE OF ALVEOLI
The alveolar lining cells consists of
1. Type I cells
2. Type II cells
They are also called pneumocytes.
“Bifurcation of trachea is called Carina”.
TYPE I PNEUMOCYTES
Squamous shaped cells which form the epithelial lining of alveoli
TYPE II PNEUMOCYTES
Irregular and cuboidal shaped cells which secretes a substance called Surfactant
SURFACTANT
The internal area of an alveoli is provided with a thin layer of fluid called as Surfactant secreted by type II cells.
FUNCTION OF SURFACTANT
1. It reduces the internal surface tension of alveoli which prevent it collapsing during expiration.
2. It increases the compliance.
3. It stabilize the alveoli.
4. It also helps to keep the alveoli dry.
LUNGS
Lungs are paired, soft, spongy, elastic and highly vascularized structures, which occupy most of thoracic cavity. In child they are pink, but with age they become dark and mottled due to inhalation of dust.
RIGHT LUNG
Partitioned into 3 lobes by two fissures.
LEFT LUNG
Divided into 2 lobes by one fissures.
PLEURAL MEMBRANES
Each lung is enclosed by two thin membranes called as Visceral and parietal pleural membranes.
PLEURAL CAVITY
In between the membranes there is a narrow cavity, the pleural cavity filled with pleural fluid which acts as lubricant.
FUNCTION OF CAVITY
1. Cardinal function is to exchange gases.
2. Phagocytosis of air borne particles
3. Temperature regulation
4. Removal of water
5. Maintainence of acid-base balance (by elemination of CO2)
6. Acts as Reservoir of blood.
BREATHING
DEFINITION
“Breathing is the process of taking in (inspiration or inhalation) and giving out of air (expiration or exhalation) from the atmosphere up to the respiratory surface and vice versa”
TYPES OF BREATHING
There are two types of Breathing
Negative pressure Breathing
Positive pressure Breathing
NEGATIVE PRESSURE BREATHING
Normal breathing in man is termed as negative pressure breathing in which air is drawn into the lungs due to negative pressure (decrease in pressure in thoracic cavity in relation to atmospheric pressure).
POSITIVE PRESSURE BREATHING
“In this kind of breathing, lungs are actively inflated during inspiration under positive pressure from cycling valve”.
EXAMPLES
Frog uses positive pressure breathing.
PHASES OF BREATHING
1. INSPIRATION OR INHALATION
2. EXPIRATION OR EXHALATION
(1) INSPIRATION
DEFINITION
“Inspiration is an energy consuming process in which air is drawn into the lungs due to negative pressure in thoracic cavity”
MECHANISM
During inspiration volume of thoracic cavity increases which creates a pressure (intra thoracic) that sucks the air into the lungs.
INCREASE IN VOLUME OF THORACIC CAVITY
Volume of thoracic cavity increases due to
1. Inc. in Anterio-posterior diameter
2. Inc. in Vertical diamter.
INCREASE IN ANTERIO-POSTERIOR DIAMETER During contraction of external intercostals muscle, the ribs as well as the sternum move upward and outward, which causes the increase in anterior-posterior diameter of thoracic cavity.
INCREASE IN VERTICAL DIAMETER
Vertical diameter of thoracic cavity inc. due to Contraction (descent) of Diaphragm which makes it flat.
As a consequence thoracic cavity enlarges and the pressure is developed inside the thoracic cavity and ultimately in the lungs. So the air through the respiratory tract rushes into the lungs upto the alveoli where gaseous exchange occurs.
(2)EXPIRATION
DEFINITION
“It is reserve of inspiration. The passive process in which air is given out of lung due to increased pressure in thoracic cavity is called “Expiration”
MECHANISM
During expiration, elastic recoil of pulmonary alveoli and of the thoracic wall expels the air from the lungs.
DECREASE IN VOLUME OF THORACIC CAVITY
Volume of thoracic cavity ↓ due to
1. DECREASE IN ANTERIO-POSTERIOR DIAMETER
2. DECREASE IN VERTICAL DIAMETER
(1) DECREASE IN ANTERIO-POSTERIOR DIAMETER
It is caused by relaxation of external intercostals muscles and contraction of internal intercostals muscles which moves the ribs and sternum inward and downward.
(2) DECREASE IN VERTICAL DIAMETER
It is caused by relaxation of diapharagm which makes it dome shaped thus reducing the volume of thoracic cavity.
As a consequence, the lungs are compressed so the air along with water vapours is exhaled outside through respiratory passage.
CONTROL OF RATE OF BREATHING
Rate of breathing can be controlled by two modes.
VOLUNTARY CONTROL
INVOLUTARY CONTROL
VOLUNTARY CONTROL
Breathing is also under voluntary control by CEREBRAL CORTEX
EXAMPLES
We can hold our breath for short time or can breath faster and deeper at our will.
INVOLUNTARY CONTROL
Mostly, rate of breathing is controlled automatically. This is termed as Involuntary control which is maintained by coordination of respiratory and cardio-vascular system.
TWO MODES OF INVOLUNTARY CONTROL
A. NERVOUS CONTROL (through respiratory centers in brain)
B CHEMICAL CONTROL (through chemoreceptors)
(A) NERVOUS CONTROL

• Control of rate of breathing by nervous control is through the Respiratory centers in Medulla oblongata which are sensory to the changes in Conc. of CO2 and H+ present in the cerebro-spiral fluid (CSF).

RESPIRATORY CENTRES IN MEDULLA
Two center are present

(1) DORSAL GROUP OF NEURONS
Medulla contains a dorsal group (Inspiratory group) of neurons responsible for inspiration
FUNCTION
In response to increase conc. of CO2 and H+ (decreased pH), it sends impulses to the intercostals muscles to increase the breathing rate
(2) VENTRAL GROUP OF NEURONS
Another area in the medulla is ventral (expiratory) group of neurons.
FUNCTION
It inhibits the dorsal group and mainly responsible for expiration
(B) CHEMICAL CONTROL
Chemical control of rate of breathing is through chemoreceptors.
LOCATION OF CHEMORECEPTORS
AORTIC BODIES
CAROTID BODIES
AORTIC BODIES
The peripheral chemoreceptors which are located above and below the arch of aorta are called Aortic bodies. It sends impulses to medulla through Vagus nerve.
CAROTID BODIES
Chemoreceptors which are located at the bifurcation of carotid arteries are called Carotid bodies. It sends impulses to medulla through Glossopharyngeal nerve.
FUNCTION
Inc. in concentration of CO2 and H+ in blood are basic stimuli to increase the rate of breathing which are monitered by these chemoreceptors and then send the impulses to medulla oblongata which produce action potential in inspiratory muscles.
DISORDERS OF RESPIRATORY TRACT
(1) LUNG CANCER (BRONCHIAL CARCINOMA)
CAUSES

• Smoking is a major risk factor either acitively or passively.
• Asbestos, nickel, radioactive gases are associated with increased risk of bronchial cascinoma

PHYSIOLOGICAL EFFECTS
+ LOSS OF CILIA
The toxic contents of smoke such as nicotine and SO2 cause the gradual loss of cilia of epithelical cells so that dust and germ are settled inside the lungs.
+ ABNORMAL GROWTH OF MUCOUS GLANDS
Tumor arises by uncontrolled and abnormal growth of bronchial epithelium mucous glands. The growth enlarges and some times obstruct a large bronchus.
The tumours cells can spread to other structures causing cancer.
SYMPTOMS

• Cough- due to irritation
• Breath lessness – due to obstruction.

(2)TUBERCLOSIS (KOCH’S DISEASE)(INFECTIOUS DISEASE OF LUNG)
CAUSE
Caused by a Bacterium called as “MYCOBECTERIUM TUBERCLOSIS”
PHYSIOLOGICAL EFFECTS

• Tuber Bacili causes
• Invasion of infected region by macrophages
• Fibrosis of lungs thus reducing the total amount of functional lung tissues

These effects cause

• Increased work during breathing
• Reduced vital and breathing capacity
• Difficulty in diffusion of air from alveolar air into blood.

SYMPTOMS

• Coughing (some time blood in sputum)
• Chest pair
• Shortness of breath
• Fever
• Sweating at night
• Weight loss
• Poor apetite

PREVENTION
A live vaccine (BCG) provides protection against tuberclosis.
3.COPD-(CHRONIC OBSTRUCTIVE PULMONARY DISEASE)
They include
A. Emphysema
B. Asthma
(3-A)EMPHYSEMA
CAUSES
It is a chronic infection caused by inhaling Smoke and other toxic substances such as Nitrogen dioxide and Sulphur dioxide
PHYSIOLOGICAL EFFECTS

• Long infection – Irritants deranges the normal protective mechanisms such as loss of cilia, excess mucus secretion causing obstruction of air ways
• Elasticity of lung is lost
• Residual volume increases while vital capacity decreases.
• Difficulty in expiration due to obstruction
• Entrapment of air in alveoli
• All these together cause the marked destruction of as much as 50-80% of alveolar walls.
• Loss of alveolar walls reduces the ability of lung to oxygenate the blood and remove the CO2
• Oxygen supply to body tissues especially brain decreases.

SYMPTOMS

• Victim’s breathing becomes labored day by day.
• Patient becomes depressed, irritable and sluggish.
• Concentration of CO2 increases which may cause death.

(3-B) ASTHAMA
“Respiratory tract disorder in which there are recurrent attacks of breathlessness, characteristically accompanied by wheezing when breathing out.”
CAUSES
It is usually caused by Allergic hypersensitivity to the plant pollens, dust, animal fur or smoke or in older person may be due to common cough.
Heridity is major factor in development of Asthma.
PHYSIOLOGICAL EFFECTS

• Localized edema in walls of small bronchioles.
• Secretion of thick mucus.
• Spastic Contraction of bronchial smooth muscles (so the resistance in air flow increases).
• Residual volume of lung increases due to difficulty in expiration.
• Thoracic cavity becomes permanently enlarged.

SYMPTOMS

• The asthmatic patient usually can inspire quite adequately but has great difficulty in expiring.

LUNG CAPACITIES
1. TOTAL AVERAGE LUNG CAPACITY
DEFINITION

“It is the maximum volume in which the lung can be expanded with greatest possible inspiratory efforts.”

Or
“Total lung capacity is the combination of residual volume and vital capacity.
VALUE
Total lung capacity = 5000 cm3 or 5 lit of air.
2. TIDAL VOLUME
“The amount of air which a person takes in and gives out during normal breathing is called Tidal Volume.”
VALUE
450cm3 to 500 cm3 (1/2 litre)
3. INSPIRATORY RESERVE VOLUME
DEFINITION
‘“Amount of air inspired with a maximum inspiratory effort in excess of tidal volume.”
VALUE
200 cm3 or 2 lit. (Average value)
4. EXPIRATORY RESERVE VOLUME
DEFINITION
“Amount of air expelled by an active expiratory effort after passive expirations.”
VALUE
1000 cm3 or 1 litre.
5. VITAL CAPACITY
DEFINITION

“After an extra deep breath, the maximum volume of air inspired and expired is called Vital capacity.”
Or
“It is the combination of inspiratory reserve volume, expiratory reserve volume and tidal volume.”
VALUE
Averages about 4 litre.
6. RESIDUAL VOLUME
DEFINITION

“Amount of air which remains in lung after maximum expiratory effort is called Residual volume.”
VALUE
Approximately 1 litre or 1000 cm3.
IMPORTANCE OF LUNG CAPACITY

• Residual volume prevent the lung from collapsing completely.
• Responsible for gaseous exchange in between breathing.
• It is not stagnant since inspired air mixes with it each time.
• Aging or Emphysema, etc can increase the residual volume at the expense of vital capacity.

HAEMOGLOBIN
INTRODUCTION
“Haemoglobin is an iron containing respiratory pigment present in the red blood cells of vertebrates and responsible for their red colour.”
STRUCTURE
Haemoglobin consists of
1. Heme
2. Protein (globin like chains)
1. HEME
One Haemoglobin molecule consists of 4 molecules of Heme. Each Heme molecule contains an iron (Fe++) binding pocket. Thus one molecule of Haemoglobin can combine with 4 iron atoms.
2. GLOBIN
Each Hb molecule contains four globin like chains (Two α chains and Two β chains).
ROLE OF HB DURING RESPIRATION
Two major functions are performed by Hb.
1. Transport of O2 from lung to tissues.
2. Transport of CO2 from tissues to lungs.
1. “TRANSPORT OF O2 FROM LUNGS TO TISSUES”
“Nearly 97% of O2 is transported from the lungs to the tissues in combination with Hb.”
ATTACHMENT OF O2 WITH HB
It is the iron of Hb molecule which reversibly binds with oxygen. One Hb molecule can bind 4 molecules of O2. Thus due to Hb, blood could carry 70 times more oxygen than plasma.
MECHANISM OF TRANSPORT

• Due to high O2 concentration in alveolar air, the O2 moves from air to the venous blood where O2 concentration is low.
• It combines loosely with Hb to form Oxyhemo Globin.
• In this form, O2 is carried to the tissues where due to low oxygen concentration in tissues, oxy Hb dissociates releasing oxygen, which enters in tissues.

Whole process can be represented by following equation.
2. “TRANSPORT OF CO2 FROM TISSUES TO LUNGS”
“Haemoglobin is also involved in 35% of transport of CO2 from tissues to alveolar blood capillaries in alveoli.”
ATTACHMENT OF CO2 WITH HB
CO2 binds reversibly with NH2 group of Hb to form loose compound called “Carboamino Haemoglobin.”
MECHANISM OF TRANSPORT

• Carbon dioxide due to its higher concentration in tissue diffuses out into the blood where it combines with Hb to form Carboamino Hb.
• In the alveoli it breaks and CO2 diffuses out into the Alveoli from where it is expired.

MYOGLOBIN
INTRODUCTION
“Myoglobin is a heme protein, smaller than Hb, found in muscles and giving red colour to them.
STRUCTURE
Myoglobin consists of one heme molecule and one globin chain. It can combine with one iron (Fe++) atom and can carry one molecule of O2.
FUNCTION OF MYOGLOBIN

• Myoglobin has high affinity for O2 as compared to Haemoglobin so it binds more tightly.
• It stores the O2 within the muscles.
• It supplies the O2 to the muscles when there is severe oxygen deficiency (During exercise)

It can be represented as follows:
Mb + O2 ↔ MbO2
TRANSPORT OF GASES
Oxygen and carbondioxide are exchanged in, Alveoli by Diffusion.
O2 TRANSPORT
Blood returning into the lungs from all parts of body is depleted from oxygen. This deoxygenated blood is dark maroon in colour to appear bluish through skin. It becomes oxygenated in the lungs.
TWO FORMS OF O2 IN BLOOD
O2 is transported in the blood in two forms:

• Dissolved form (3%)
• Combination with Hb (97%) ® Oxyhaemoglobin

MECHANISM OF O2 TRANSPORT
+ DIFFUSION OF O2 FROM ALVEOLUS INTO PULMONARY BLOOD
The air inhaled into the lungs has high concentration of oxygen while venous blood in pulmonary capillaries has low in concentration. Due to this difference in concentration across the respiratory surface, oxygen diffuses into the blood flowing into capillaries around the Alveoli. Now blood becomes oxygenated which is bright red in colour.
+ DIFFUSION OF O2 FROM CAPILLARIES INTO CELLS
Concentration of O2 in the arterial end of capillaries is much more greater than concentration of O2 in the cells. So O2 diffuses from the blood to the body cells. Since the blood takes in oxygen much more rapidly than water. Thus it can transport enough oxygen to the tissues to meet their demand.
CO2 TRANSPORT
Blood returning from tissues contain excess of CO2 as a respiratory by-product, which is eliminated from the body during expiration in the lungs.”
THREE FORMS OF CO2 IN BLOOD

• Dissolved form (in plasma) – 5%
• In form of HCO3- (in RBC’s) – 60%
• In combination with Hb (Carboamino Hb) – 35%

+ DISSOLVED FORM
Only 5% of CO2 is transported in dissolved form in plasma. Here it combines with H2O of plasma to form H2CO3. But this reaction is very slow as plasma does not contain Carbonic Anhydrase to accelerate this reaction.
Reactions can be represented by following equations.
CO2 + H2O ↔ H2CO3
H2CO3 ↔HCO3- + H+
HCO3- + k+ ↔ KHCO3
+ IN FORM OF HCO3-
60% of CO2 is transported in the blood in form of HCO3- in RBC’s. Here it combines with water to form H2CO3. But this reaction occurs rapidly in RBC’s due to presence of Carbonic Anhydrase.
Reactions can be represented by following equations
CO2 + H2O ↔ H2CO3
H2CO3 ↔ HCO3- + H+
HCO3- + Na+ ↔ NaHCO3
+ IN COMBINATION WITH HB
As discussed previously in role of Hb.
MECHANISM OF CO2 TRANSPORT
+ DIFFUSION OF CO2 FROM CELLS INTO CAPILLARIES
CO2 is continuously synthesizing in the tissues as a result of metabolism. Thus due to its higher concentration. CO2 diffuses from the tissues into blood, which becomes deoxygenated.
+ DIFFUSION OF CO2 FROM PULMONARY BLOOD INTO ALVEOLUS
Blood returning from tissues contain high concentration of CO2. This blood is brought to lungs, where CO2 diffuses from the blood into alveolus where its concentration is lower.
FACTORS EFFECTING THE TRANSPORT OF GASES
Following are some factors, which influence the transport of respiratory gases across the alveolar wall.
1. Concentration Gradient
2. Presence of competitor such as CO
3. Moisture
4. Surfactant
5. pH