ModernPhysiology Paper2

Function of Small Intestine

• Function of large intestine

Movements of the gut

• Deglutition

• Peristalsis

• Defecation

• Enteric nervous system

Acid-Base Balance

• Acid-Base Balance

• Water balance

• Electrolyte balance

Study of basic components of food

• Digestion of Carbohydrate

• Digestion o f proteins

• Digestion o f Fat

Carbohydrate Metabolism

• Proteins Metabolism

• Lipid Metabolism

Vitamins

Second Paper PART-B

Chapter- 1 Haemopoetic system

• Composition of Blood

• Function of Blood

• Function of Blood cells

• Haemopoiesis

Erythropoiesis

Leucopoiesis

Megakaryocyto poiesis

Composition of bone marrow

Functions of bone marrow

Haemoglobin

Mechanism of blood clotting

Anticoagulants

Physiological basis of blood groups

• Plasma proteins

Anaemia

Jaundice

Chapter - 2 Immunity

• Definition & classification

• Innate Immunity

• Acquired Immunity

• Different mechanisms involved in acquired immunity system

• Immunization

• Hypersensitivity

Chapter - 3

• Comparison of physiology of skeletal, smooth and cardiac muscles

• Physiology of muscle contraction

Chapter - 4

Cardio-Vascular system

• Functional anatomy of cardiovascular system

• Cardiac cycle

• Heart sounds

• Regulation o f cardiac output

• Venous return

• Physiological basis of ECG

• Heart-rate and its regulation

• Arterial pulse

• Systemic arterial blood pressure

• Mechanism of PB control

Chapter - 5 Adipose tissue

• Adipose tissue

• Lipoproteins

Chapter - 6 -Skin/Integument

• Functions of skin

• Sebaceous gland

• Sweat glands

Chapter - 7 Reproductive systems

• Physiology of Male Reproductive System

• Physiology of Female Reproductive System

• Description of ovulation

• Spermatogenesis

• Oogenesis

• Menstrual cycle

Chapter - 8 Excretory Systme

• Functional anatomy of urinary tract

• Functions of kidney

• Mechanism of formation of urine

• Control of Micturition

• Formation of faeces

• Mechanism o f defecation

Chapter - 9 Endocrine Glands

• General introduction of endocrine system

• Classification of hormones

• Characteristics of hormones

• Physiolocal study o f endocrine glands

• Pituitary gland

• Thyroid gland

• Para thyroid gland

• Supra renal gland

• Endocrine function of pancreas

• Pineal gland

• Thymus

HAEMOPOETIC SYSTEM

COMPOSITION OF BLOOD:

• Blood is a highly complex fluid, composed of two parts:

  • A. Liquid, called the plasma.

  • B. Blood corpuscles, different types of cells suspended in the plasma.

Plasma :

• Plasma is a clear, straw-colored fluid portion of the blood representing 55% of the total blood volume.

  • It contains 91% water and 9% solids.

  • The solids comprise 1% inorganic molecules and 8% organic molecules.

Major inorganic molecules:

• Extracellular: $"Na^+, Ca^{2+}, Cl^-, HCO_3^-"</p></li><li><p>Intracellular:$"K^+, Mg^{2+}, Cu^{2+}, PO_4^{3-}"

• $Fe^{2+}, Fe^{3+}$

Organic molecules (8%):

• 7% are plasma proteins.

• 1% are other substances like non-protein nitrogenous (NPN) substances, sugar, fats, enzymes, & hormones.

Plasma Protein:

• Normal value: 6.4-8.3 gm %

  • Components:

  • 55% Albumin: 3-5 gm% (Average 4.8 gm%)

  • 38% Globulin: 2-3 gm% (Average 2.3 gm%)

    • $"\alpha Globulin : 0.79 - 0.84 gm$

    • $"\beta Globulin : 0.78-0.81 gm$

    • $"\gamma Globulin : 0.66- 0.70 gm$

    • A/G ratio = 1.7/1

  • 7% fibrinogen : 0.3 gm%

  • Prothrombin : 40 mg%

Non-protein Nitrogenous (NPN) substances:

• Normal value : 28-40 mg%

• Derivatives of food and waste products of tissue catabolism.

  • Include:

  • Urea :20-40 mg%

  • Uric Acid :2-4 mg%

  • Creatine : 1-2 mg%

  • Creatinine : 0.6 -1.2 mg%

  • Xanthine : Traces

  • Hypoxanthine : Traces

Other substances:

• Neutral fats (Triglycerides) :30-150 mg%

• Phospholipids(lecithin,sphingomyelin,andcephalin etc : 150-300mg%)

• Glucose (Fasting) : 70-90 mg%

• Cholesterol :150-250mg%

Blood cells:

• The cellular elements of blood represent 45% of the total blood volume, called Packed cell volume (PCV) or Hematocrit.

  • Includes:

  • Erythrocytes or Red blood corpuscles (RBCs) : Normal count : 5 million/Cumm $5 X 10^6/ cmm$

  • Leucocytes or white blood corpuscles(WBCs) : Normal count : 4000- 11000 cumm $4-11 X 10^3/ cmm$

  • Platelets or Thrombocytes: Normal count : 1.5-4 lacs/cum $0.15-0.4 X 10^6/ cumm$

FUNCTION OF BLOOD

I. Respiratory:

• Blood transports oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs.

II. Nutritive:

• Blood conveys absorbed food materials, glucose, amino acids, fatty acids, vitamins, electrolytes, and trace metals from the alimentary canal to the tissues for utilization and storage.

• It also carries nutritive material from one place of the body to the other (e.g., from storage depots to tissue cells).

III. Excretory:

• Blood transports the metabolic wastes or waste products of cellular activity (e.g., urea, uric acid, creatinine) to the organs of excretion (kidney, skin, and intestines) for their removal.

IV. Maintenance of acid-base equilibrium:

• By its efficient buffering power (e.g., plasma proteins, reduced and oxidized hemoglobin) and with the help of the kidney, skin, and lungs, it helps maintain a constant reaction of the body.

V. Maintenance of ion balance:

• Between the cells and the surrounding fluid.

VI. Maintenance of water balance:

VII. Regulation of body temperature:

• The water content of blood possesses three qualities by which blood preserves a narrow range in body temperature:

  • High specific heat: Buffers sudden changes in body temperature by absorbing a large amount of heat.

  • High conductivity: Helps in quick distribution of heat by uniform distribution throughout the body.

  • High latent heat of evaporation: Since water is constantly evaporating from skin and lungs, a large amount of heat is lost.

VIII. Regulation of blood pressure:

• By change in volume and viscosity (hematocrit value) of blood.

IX. Blood acts as a vehicle:

• Through which hormones, vitamins, and other essential chemicals are brought to their place of activity.

X. Defensive action:

• The blood acts as a great defensive mechanism in 2 ways:

  • The white cells due to their phagocytic properties engulf bacteria and foreign particles.

  • It develops antibodies which combat toxic agents.

XI. By the property of coagulation:

• It guards against hemorrhages

XII. The plasma proteins of blood have various functions:

• Exerts the osmotic pressure influencing the exchange of fluid between blood and tissue.

• Acts as a reservoir of proteins.

• Combines with many substances (e.g., iron, thyroxin, and steroid hormones) to form transportable complexes from which the active components are released at the appropriate sites.

XIII. Blood forms the internal environment of the body (coined by Claude Bernard):

• Or milieu interjuy

FUNCTION OF BLOOD CELLS

A. Function of Red blood corpuscle or Erythrocyte:

1. Respiratory: Red cells carry oxygen and carbon dioxide.

2. Acid-base balance: They help to maintain acid-base balance. It is carried out by the buffering action of hemoglobin and other intracellular buffers.

3. Red cells maintain ion balance: By the special permeability of cell membrane, the red cells help to maintain balance of positive and negative ions in the blood.

4. Viscosity of Blood: Red cells help to maintain the viscosity of blood.

5. Various pigments are derived from hemoglobin after the disintegration of the red cells (e.g., bilirubin, biliverdin).

B. Function of white blood corpuscles or leucocyte:

1. Phagocytosis: When bacteria invade the body, leucocytes pass out of blood vessels and surround the threatened area. Through pseudopodial processes, they engulf the bacteria and destroy them. This process is called phagocytosis.

• Neutrophils are the first cells to seek out, ingest, and kill the bacteria, thus called the body?s first line of defense against bacterial infections.

• Monocytes follow the neutrophils in areas of infections or inflammation and constitute a second line of defense.

• Eosinophils and lymphocytes also have this action, but lesser as compared to neutrophils & monocytes. In chronic inflammation, lymphocytes play an important role.

1. Antibody formation: Lymphocytes manufacture globulin fraction of serum globulin.

• Immune bodies are associated with globulin fraction. So lymphocytes play an important role in the defensive mechanism of the body of an immunological nature.

• T lymphocytes produce cellular or cell-mediated immunity, and B lymphocytes produce humoral immunity.

1. Formation of fibroblasts: It is believed that lymphocytes may be converted into fibroblasts in an area of inflammation and thus help the process of repair.

2. Manufacture of trephones: Leucocytes manufacture certain substances from plasma protein which exert great influence on the nutrition, growth, and repair of tissue. These substances are called trephones.

3. Secretion of heparin: The basophil leucocytes are supposed to secrete heparin, which prevents intravascular clotting.

4. Anti-histamine function: Eosinophils collect at the sites of allergic reactions and limit their intensity by degrading the effects of mediators (e.g., histamine, bradykinin) and inhibit mast cell and basophil degranulation.

5. Anti-parasitic function: Eosinophils attack parasites that are too large to be engulfed by phagocytosis. Eosinophil granules release chemicals (peroxidase) which are toxic to larvae of parasites.

6. Anti-cancerous function: Monocytes may also kill tumor cells after sensitization by lymphocytes. Monocytes synthesize complement and other biologically important substances like prostaglandin E etc.

7. Formation of tissue macrophage: Even in absence of any infection, the monocytes leave the blood and enter the extravascular tissue. In these tissues, they are called macrophage. Their main function is to remove various undesirable substances.

Function of platelets:

1. Hemostatic mechanism: This process seems to play by the dual functions of platelets such as agglutination and coagulation. The cessation of blood flow from ruptured blood vessels takes place through simultaneous coagulation and agglutination by platelets.

2. Initiate blood clotting: When blood is shed, the platelets disintegrate and liberate thromboplastin which activates prothrombin into thrombin.

3. Hasten clot retraction: Speed of clot retraction (i.e., syneresis) is directly proportional to the number of platelets present, and this retraction process is dependent upon the thrombosthenin, (contractile protein of platelets) in presence of ATP & magnesium ions.

4. Phagocytic function: Platelets help in phagocytosis of carbon particles Viruseg and immune complexes.

5. When platelets disintegrate, 5 hydroxy tryptamine and histamine are liberated. 5 hydroxy tryptamine has vasoconstrictor effect and helps in hemostatic mechanism.

6. Repair capillary endothelium: While in the circulation, the platelets adhere to the damaged endothelial lining of the capillaries and thus bring about a speedy repair.

HAEMOPOIESIS

• It is the origin, development, and maturation of blood cells ie RBCs, WBCs, and platelets.

• Therefore, the term haemopoiesis includes:

  • Erythropoiesis, ie origin, development & maturation of RBCs

  • Leucopoiesis ie origin, development & maturation of WBCs.

  • Mega-karyocytopoiesis ie origin, development &maturation of platelets.

Theories of haemopoiesis:

• Monophyletic theory: Most acceptable. According to this theory, different types of blood cells arise from a single cell, called the pluripotent stem cell, present in bone marrow. % of the cells in the bone marrow belong to WBCs producing myeloid series, and only 25% are of erythroid series.

• Polyphyletic theory: There are separate stem cells present in the bone marrow for each main variety of blood cells (ie granulocytes, monocytes, lymphocytes, erythrocytes and platelets).

ERYTHROPOIESIS:

• It is the process of origin, development & maturation of erythrocytes.

During intrauterine life:

• There are three successive stages of blood formation in the embryo and fetus.

  • Mesoblastic stage.

  • Hepatic stage.

  • Myeloid stage

1. Mesoblastic stage:

   • In the early embryo up to 3 months of fetal life, R.B.Cs are formed from mesoderm of yolk sac or area vasculosa.

   • Since erythropoiesis occurs wit the blood vessel, therefore this stage is also called intravascular erythropoiesis.

2. Hepatic stage:

   • After 3 months of fetal life, the liver and spleen are the site of blood formation

3. Myeloid stage:

   • This stage begins approximately at the fifth month, with the establishment of the placental circulation (ie from the middle of fetal life, erythropoiesis occurs in the bone marrow).

   • Hepatic and myeloid stages are extravascular erythropoiesis.

In Children:

• Erythropoiesis occurs in:

  • All bones with red marrow (mainly)

  • Liver

  • Spleen

In Adults ie after 18-20 years of age:

• Erythropoiesis occurs from red bone marrow, which includes:

  • Ends of long bones like humerus and femur because the shaft is converted to yellow marrow.

  • Skull

  • Vertebrae

  • Ribs.

  • Sternum & Pelvis

Stages of erythropoiesis:

• Haemocytoblast

• Pro erythroblast

• Early normoblast

• Intermediate Normoblast

• Late Normoblast

• Reticulocyte

• Erythrocyte

Regulation of erythropoiesis:

A. General factors
B. Special maturation factors

A. General Factors:

• Hypoxia: Hypoxia means lack of oxygen at the tissue level.

  • When air with low oxygen tension (as in high altitude) is breathed for some length of time, the red cell count rises due to the liberation of erythropoietin or the hemopoietin or erythrocyte-stimulating factor.

  • It stimulates the bone marrow and Increases the rate and maturation of red cell formation.

  • Erythropoietin production reaches its peak within 24 hrs of the hypoxic stimulus.

B. Special Maturation Factor:

1. Dietary Factors: Proteins help in globin formation. Iron, manganese, copper, cobalt, and nickel help in heme formation. Calcium increases iron absorption from GIT. Vitamin C, B12, and folic acid help in the synthesis of nucleic acid, which help in the development and maturation of RBC.

2. Castle’s Intrinsic Factor (IF): Produced by parietal cells of the stomach. It helps in the absorption of vitamin B12 from the ileum.

3. Extrinsic Factor (EF): Intrinsic factor with extrinsic factor form a hematinic principle which helps in the maturation of R.B.Cs (For conversion of proerythroblast to mature RBC).

• In the process of erythropoiesis, 7 days are required to form a reticulocyte from a proerythroblast and another 2 days from a reticulocyte to a mature erythrocyte.

• Normal Red cell count:

  • The normal average count in the adult male is 5 million and in female 4.5 million per cubic millimeter.

  • In infants, the count is 6-7 million / cmm.

  • In the fetus, the count is 7-8 million/ cmm.

Life span: 120 days.

• The mature human erythrocyte is a circular, biconcave, non-nucleated disc which neither contains mitochondria nor ribosomes.

• Composition:

  • 62.5% water.

  • 35.0% hemoglobin

  • 02.5% other substances such as protein, sugar, lipid.

Diameter: 6.5 – 8.8 (\mum). Average 7.2 (\mum).

LEUCOPOIESIS:

• Leucopoiesis is the process of origin, development & maturation of leucocytes (WB.C).

• Leucopoiesis is of two types:

  • Granulopoiesis

  • Agranulopoiesis

A. Granulopoiesis:

• It is the process of origin, development & maturation of granulocytes. Its duration is 3 days.

• Granulocytes develop mainly and exclusively in the reticulum cells of red bone marrow. Reticulum cells multiply by mitosis forming primitive W.B.C. s (stem cell)

  • Primitive W.B.Cs (Stem cell) Myeloblast Pre myelocyte Myelocyte proper Meta myelocyte Mature WBC s

B. Agranulopoiesis:

• Agranulopoiesis is the process of origin, development & maturation of agranulocytes.

• Agranulopoiesis mainly occurs in the lymphoid tissues (thymus, spleen, lymph nodes, peyer patches, tonsil etc) and in the bone marrow to a slight extent.

  • Lymphnode Lymphoblast Lymphocyte

  • Reticulumcyte Monoblast Monocyte.

Diffrential Leucocyte count (DLC):

• The different types of leucocytes present in the circulation are:

  • Granulocytes (Neutrophils, Eosinophils, Basophils)

  • Agranulocytes (Lymphocytes and Monocytes)

Total leucocyte count (TLC):

• At birth: 20,000/Cumm count decreases after 2 week, reaching normal adult value at 5-10 years.

• In adults: 4,000-11000/Cumm

1. Neutrophil or polymorphonuclear leucocyte

   • Size : 10 – 14 (\mum) diameter.

   • Nucleus : Purple in color Multi-lobed.

   • Cytoplasm : Slight bluish in color, granular.

   • Granule : Fine sand like particles, called pin point granules. Neutrophilic in nature, ie take both the acidic and basic stains. Contain varieties of enzymes and proteolytic enzymes they can lyse any type of substances, the granules are thus referred to as lysosomes.

   • Functions:
     - Phogocytosis
     - First line of defence
     - Contain endogenous pyrogen : Which is an important mediator o f febrile response to bacterial pyrogens.

   • Applied Aspect:
     - Neutrophillia:
     - Physiological:
     - Exercise
     - Pregnancy, menstruation and lactation.
     - After injection o f epinephrine.
     - Pathological :
     - Acute pylogenic infections.
     - Following tissue destruction eg : burns, after surgery, myocardial infarction, after hemorrhage.
     - Neutropenia :
     - Physiological :
     - Inchildren (Normalcount= 40%)
     - Pathological :
     - Typhoid / para typhoid fever Bone marrow depression., Viral infection, Protozoal infection.

2. Eosinophil:

   • Size : 10-14 (\mum) diameter.

   • Nucleus : Purple colour. Usually 85% cells bilobed and remaining 15% cells are trilobed nucleus.

   • Cytoplasm : Acidophillic - therefore appear light pink
     in color, Granular.

   • Granules : Coarse. Stain bright red with acidic die. Contain peroxidase and lysozymes.

• Function: - Mild phagocytosis. - Limits allergic reaction intensity by degrading the effects o f mediator & inhibit mast cell. - Provide mucosal immunity. - Anti parasitic effect.

  • Applied Aspect:
    - Eosinophillia means increase in eosinophills : Allergic condition infestation, skin disease
    - Eosinopenia means decrease in eosinophills : After injection of cortico Steroids.

1. Basophil:

   • Size :10-14 (\mum) diameter.

   • Nucleus : As in eosinophil.

   • Cytoplasm:Slight basophilic, therefore appears blue, granular.

   • Granules : Coarse _ Stain purple or blue with basic dye. Contain histamine and heparin.

• Function: - Mild phagocytosis. - Liberates heparin which Acts as anticoagulant and keep the blood in fluid state in the body. - Activates enzyme lipoprotein lipase which facilitates absorption of triglyceride after meals.

  • Applied aspect:

  • Basophilia means increase in basophils

    • Basopenia means decrease in basophils : After administration of corticosteroids, drug-induced reactions

1. Lymphocytes:

   • They are of two types.
     - Large lymphocyte: 10-14 (\mum) diameter.
     - Small lymphocyte (B type): 7-10 (\mum) diameter, responsible for antibody production

   1. Both have the same structure.

• Nucleus: Single, very big, purple in color.
  - Shape : Round, oval or indented central in position

• Cytoplasm : Pale blue Scanty
  - Its amount 18 always less than the amount o f nucleusFunction :Produce antibodies ie immune substance specially in delayed hyper gensitivity. Appliedlymphaemia means increase in lymphocytes Lymphatic leukemia viral infection, chronic infection as T.B. lymphopenia means reducese in lymphocytes :
  vH plastic bone marrow,AIDS,

1. Monocyte:

   • LARGEST WBC.

   • size : 10 - 18 (\mum) diameter with irregular cell outline.

   • Nucleus: Pale staining single Round or indented. Eccentric in position ie present on one side of the cell.

   • Cytoplasm: Usually pale blue, clear.:Active phagocytosis

• Function: - Second line defence - Kill tumour cell

  • Applied Aspect:
    - Monocytosis means increase in monocytes : TB, Syphilis, leukaemias.
    - Monocytopenia means decrease in monocytes :Haloplastic bone marrow.

Half life:

• The life of the different varieties of leucocytes differs.
  - Neutrophils : 2-4 days.
  - Eosinophils : 8- 12 days.
  - Basophils :12-15 days.
  - Lymphocyte :1-3 days.

BLOOD PLATELETS/THROMBOCYTES

Platelets : Small plate. Thrombo : Lumps or clot. Cytes : Cells.

Platelets are non nucleated, round or oval biconvex discs having various sizes and
covered by unit membrane. The average size is 2.5 (\mum), means smallest blood cells.

Count and variations:

• Normal count is 1.5 to 4 lacs/cumm. (Average 2.59lacs/Cumm). Its count is very much constant.

• The circulating platelets represent approx 60-75% of the platelet pool of the body, the remaining are mostly in the spleen, therefore spleen acts as a reservoir of platelets. Spleen also acts as a destructor organ of platelets.

• Life span: 8-12 days.

THROMBOPOIESIS OR MEGA KARYOCYTOPOIESIS:

• It is the process o f origin, development and maturation of platelets
  - Site of origin: Bone marrow.
  - Stages of thrombopoiesis Pluripotent stem cell Committed stem cell Megakaryoblast Pre mega karyocyte Granular mega karyocyte Platelets

Applied Aspects:

Thrombocytosis:ie increase in platelet count.

• Causes:
  - After administration of epinephrine.
  - After trauma eg. Surgery, injury, child birth etc.
  - Splenectomy.
  - Stress causes increased epinephrine release.

Thrombocytopenia:ie decrease in platelet count.
- Bone marrow depression.
- Hypersplenism, Viral infection eg. Dengue fever, Drug hypersensitivity,

BONE MARROW:

• The terms bone marrow and myeloid tissue are often used synonymously.

• Bone marrow is the cellulovascular tissue occupying the medullary cavities and the cancellous spaces of the bone.

• The volume o f the marrow is 70 ml at birth and 4000 ml in the adult.

• In the adult only about half the marrow is in an active state known as red bone marrow, the remainder being inactive is known as yellow bone marrow.

Red Bone Marrow

• It consists o f numerous blood cell of all kinds and their precursor Erythroid & myeloid o freticulum cells and fibers.

• It is also called active marrow

• It includes the ends of long bone

• It is of red Color

Yellow Bone Marrow

• It co It consists o f fat cells, blood vessels and a minimal framework Marrow

• It is also called inactive marrow.

• It includes shaft of bones.

• It is of yellow colour.

Composition:

• Cells o f myeloid series.

• Cells of erythroid series.

• Mega karyocytes.

Function:

1. Haematopoietic (haemopoietic) Function:

• Production of myeloid, erythroid, and mega karyocytes elements are the important function of bone marrow.Marrow contains abou $5.6 X 10^9$ erythroid precursors/kg body wt. and $11.4 X 10^9$ neutrophil precursors/kg body wt.

1. Erythroclasia o r destruction o f R.B.C.:

   • In the bone marrow not only theblood cells are formed but also the abnormal, imperfect, damaged and aged RBC are destroyed.

     • These cells are sequestered o r trapped and phagocytosed in the macrophages o f the bone marrow.

2. Storage function:

   • Bone marrow is an important site for storage o f iron in the form o f ferritin and haemosiderin coming from food source as transferrin and also from destruction o f RBC through phagocytosis.

3. Help in the synthesis of hemoglobin:

   • Stored iron in bone marrow are easily utilized for the synthesis of hemoglobin.

4. Reticulo endothelial function:

   • Bone marrow plays an important role in the inactivation of toxins or other toxic substances o f body.
     -The free macrophages of the bone marrow are increased during the invasion o f toxins or during hemolysis.

5. Immunological function:

   • Regarding its immunological function, the marrow is not so competent as it is found in spleen and lymph nodules.

6. Osteogenic function:

   • The celiular elements which take part in the formation of bone such as osteoclast, osteoblast, osteocytes, endosteum, blood vessels are foun with in the marrow. °Connective tissue functions: Due to its different connective tissue contents, bone marrow performs several functions associated with connective tissue.

HAEMOGLOBIN:

Structure: The red oxygen-carrying pigment in the RBCs of vertebrates is hemoglobin. It is a chromoprotein consisting of two parts: A specific simple protein ie globin ~ 96%. A non specific prosthetic group ie an iron containing pigment called heme ~ 04%.

Globins: It is a protein built from 4 polypeptide chains, two and two β chains. qherefore, the normal adult hemoglobin (Hb A) is written as Hb A (${{\alpha}}<em>2{{\beta}}</em>2$). Each polypeptide chain is associated with one heam group.

Heam: It is an iron-containing pigment (porphyrin) called iron-protoporphyrin IX. Iron: Normally, it is present in ferrous ($fe^{2+}$) form. Each 6 combines loosely and reversibly with one molecule of oxygen. Thus one molecule of hemoglobin can carry 4 molecules (8 atoms) of oxygen.

Porphyrin: The pigment part of heam is called porphyrin. It is formed by four le rings attached with another by methane bridges.

The molecular weight of hemoglobin is 68000, and it forms 95% of dry weight o f RB.C and 30-34% of wet weight.

Normal hemoglobin value: At birth 23gm% because RBC count is more. At the end o f 3 months 10.5gm% as an infant is totally on milk feed which is devoid of iron. After 3 months, hemoglobin increases gradually and at the end o f 1 year it becomes 12.5gm%

Adults:

• Males :14-18gm% (Average 15.5gm%)

• Females : 12-15.5 gm% (Average 14 gm%)

Function of hemoglobin:

1. Transport of oxygen from lungs to the tissues.
   Transport of Co, from the tissues to the lungs.
   It acts as an excellent acid-base buffer. It is responsible for 70% buffering power o f whole blood.
   It has additional (NO) nitric oxide binding power & after releasing in the tissue, it promotes vosodilation

MECHANISM O F CLOTTING:

Coagulation or clotting is defined as the process in which blood loses its fluidity and becomes ajelly like mass few minutes after it is shed out or collected in a container.

Clotting factors:
Coagulation of blood occurs through a series of reactions due to the activation o f a Sup of substances. The substances necessary for clotting are.called clotting factors.

There are Thirteen clotting factors:
Factor I: Fibrinogen
Factor II: Prothrombin
Factor Ill: Thromboplastin or tissue factor.
Factor IV : Calcium.
Factor V: Labilefactor/Proaccelerin/ accelerator globulin.
Factor VI : Accelerin.
FactorVII : Proconvertin/stablefactor/Autoprothrombin.I
Factor VI II: Antihemophilic factors.
Factor IX: Christmasfactor/plasma thrombo plastin component, Auto prothrombin II.
FactirX; Stuart prower factor.
Factor XI ; Plasma thromboplastin antecedent.
Factor XII: Hageman factor/ Glass factor/ Contact factor.
Factor XIII: Fibrinstabilizingfactor /Fibrinrase/ Laki ?lorand factor.

Stages of blood clotting:

In General, blood clotting occurs in three stages:

• Formation o f prothrombin activator.

• Conversion of prothrombin into thrombin.

• Conversion o f Fibrinogen into fibrin.

Formation of prothrombin activator:

Blood clotting commences with the formation of a substance called prothrombin activator, which converts prothrombia into thrombin. It is formed either with in the blood itself or outside the blood.

This formation o f prothrombin activator occurs through two pathways:
External pathway:
Intrinsic Pathway

Extrinsic pathway:
In this pathway, the formation o f prothrombin activator is initiated by the tissue thromboplastin, which is formed from the injured tissue (Source ous su blood)

Intrinsic pathway:
In this, the formation o f prothrombin activator!S inti plateletes, which are with in the blood it self

Intrinsic system:

• it is triggered by

  • When blood is exposed to the collagen Fibres underlying the endothelium in
    Blood vessels.

  • Change in blood constituents.

  • Exposure of blood to electronegatively Charged wettable surface such as glass

  • Inactive -> Active

    • XII -> XIIa

    • XI -> XIa

    • X -> Xa

    • VIII -> VIIIa

    • X -> Xa
      Extrinsic system:

  • It is triggered by injury to (1) Blood vessel wall. (ii) Other body tissues

  • Cause release Tissue Thromboplastin (Phospholipid, Glycoprotein)

  • Inactive? -> Active
    VII -> VIIa
    X -> Xa

-In both systems, we have activated factor Xa. This activated Xa converts V into Va in the presence of the Calcium ion.

Common Pathway
Platelet phospholipid + Ca + Va + XaProthrombin activator
Prothrombin Ca thrombin
Fibronogen Ca fibrin

-Conversion of Pro thrombin into thrombin: Pro thrombin activator, th in intrinsic