This document summarizes the composition and functions of blood. It discusses that blood is composed of plasma and cells. The cells include red blood cells, white blood cells, and platelets. Plasma is the fluid portion of blood and contains water, proteins, and other molecules. Important functions of blood include respiration, nutrition, regulation, and defense. Key components like hemoglobin, blood types, coagulation, and blood transfusion are also overviewed.

1. BLOOD
BY - MUSKAN KAPOOR

2. COMPOSITION OF BLOOD
● Total volume of blood : 5-6 litres
● Specific gravity : 1050-1060
● Viscosity : four to five times more than
water
● pH : 7.4, alkaline
● It is divided in 2 parts i.e. - cells
- plasma

3. CELLS
● The cellular elements represent
of blood represent 45% of total
blood volume known as packed
cell volume(PCV)/ haematocrit.
● It includes:- Erythrocytes or red blood
cells - 5 million cells per microliter.
- Leucocytes or white blood cells-
4,000-11,000 millions cells per microliter.
- Platelets or thrombocytes - 1.5 to 4 lacs
per microliter.

4. PLASMA
● It is clear , straw-coloured fluid portion of blood and represents 55% of total blood volume.
● It contains:- 91% water
- 9% solids , it comprise of inorganic and organic molecules.
➔ Inorganic molecules - sodium, potassium, calcium salts etc.
➔ Organic molecules - plasma proteins, other substances like
non-protein nitrogenous substances, sugar, fats ,enzymes and
hormones.
➔ Plasma proteins :- 6.4 to 8.3 g/dL
- 55% albumin (3-5g/dL)
- 38% globulin (2-3g/dL)
- 7% fibrogen (0.3g/dL)
- Prothrombin (40m/dL)

5. FUNCTIONS OF BLOOD
● Respiratory
● Nutritive
● Excretory
● Homeostatic for water, pH and electrolyte
concentration
● Regulation of body temperature
● Plasma protein function

6. IMPORTANT TERMS
● Haemoglobin - it is red, oxygen carrying pigment in RBCs.
● Oxyhaemoglobin - haemoglobin reacts with oxygen to form
oxyhaemoglobin and is represented by HbO2.
● Carbamino haemoglobin - carbon dioxide react with haemoglobin to form
carbamino haemoglobin.
● Carboxyhaemoglobin - carbon monoxide react with haemoglobin to form
carboxyhaemoglobin
● Methaemoglobin - when either reduced or oxygenated haemoglobin is
exposed to various drugs or oxidising agents .

7. FUNCTION OF HAEMOGLOBIN
● Transport of oxygen from lungs to tissues.
● Transport carbon dioxide from tissues to
lungs.
● Being a protein it acts as excellent acid-
base buffer.

8. RBCs
● FUNCTION : - Useful to identify blood groups as it contains blood group specific
substance i.e antigen on its surface.
● Haemopoiesis - it is the development of blood cells i.e RBCs, WBCs and platelets.
● It include :- Erythropoiesis i.e development of RBCs.
- Leucopoiesis - development of WBCs
- Megakaryocytopoiesis - development of platelets.

9. WBCs
● The different types of leucocytes present in the circulation are :-
- Granulocytes : it contain neutrophils, eosinophils, basophils.
- Agranulocytes : it contains lymphocytes and monocytes.
● Leucopenia - TLC decreases less than 4000 millions
cells per microliter.
● Leucocytosis - TLC increases above 11,000 millions
per microliter.
● Leukaemia - TLC is usually more than 50,000 million
per microliter.

10. FUNCTION OF GRANULOCYTES
● Neutrophil -
➔ Function - phagocytosis
- They contain fever producing substance endogenous
pyrogen.
● Eosinophil -
➔ Function - mild phagocytosis
- It collect at the sites of allergic reaction and limit their intensity.
● Basophil -
➔ Function - mild phagocytosis
- Liberates heparin which act as anticoagulant.
- Liberates histamine which is responsible for allergic manifestations

11. FUNCTIONS OF AGRANULOCYTES
● LYMPHOCYTES :
➔ Functions - produce antibodies
● Monocytes :
➔ Functions - active phagocytosis
- Monocytes enter the circulation from bone
marrow .
- They also kill tumour cells.

12. PLATELETS
● FUNCTIONS :- haemostasis
- Blood coagulation
- Clot retraction
- Phagocytic function
- Storage and transport function

13. COAGULATION OF BLOOD
● Spontaneous arrest or prevention of bleeding by physiological processes is called
haemostasis.
● MECHANISM OF HAEMOSTASIS
INJURY TO BLOOD VESSEL
FORMATION OF CLOT
SEALS OFF THE DAMAGED BLOOD VESSEL
PREVENTS further loss of blood

14. CLOTTING FACTORS

15. ● INTRINSIC SYSTEM :- It is initiated by
➔ When blood is exposed to the collagen fibres
➔ Change in blood constituents
● EXTRINSIC SYSTEM :- it is initiated
by injury to
➔ Blood vessel wall
➔ Other body tissues

17. BLOOD GROUPS
● The membrane of human RBCs contains a variety of blood group specific
antigen also called agglutinogens.
● These antigens enable the blood group of different individuals to be
differentiated .
● The chief blood group are :- classical ‘ABO’ blood groups
- Rhesus (Rh) blood group
● Classical ABO blood group

18. CLASSICAL ‘ABO’ BLOOD GROUPS
● The individuals are divided into 4 major blood groups depending on the
presence or absence in their RBCs membrane of the blood group specific
substance called A, B and O .
● A and B are group specific substances called antigen (agglutinogen) i.e in
the presence of a suitable antibody (agglutinin) cause clumping of RBCs
(agglutination).

19. RHESUS BLOOD GROUP
● RBCs of Rhesus monkeys when injected into rabbit, the rabbits respond to the
presence of an antigen in these cells by forming an antibody which agglutinates
rhesus RBCs.
● If immunised rabbit’s serum is tested against human RBCs agglutination occurs in 85%
of people these are called Rh’+’ and their serum contains no Rh antibody.
● No agglutination occurs in 15%these are called Rh ‘-’ and their serum also contain no
Rh antibody.
● In Rh system, Rh antibodies are of the IgG type and
can cross placenta.

20. BLOOD TRANSFUSION
● Group A and group B can only safely receive blood from their own
group and group O.
● Person of group AB have no circulating agglutinins and can therefore
be given blood of any type without developing a transfusion reaction
called universal recipients.
● Person of group O certain no agglutinogen and can be given to
anyone, therefore its RBCs are not agglutinated by the members of
group called universal donors.
● If time does not permit the grouping and cross matching of the
recipient ‘O’ Rh ‘-’ blood should be used.

22. THANK YOU