Blood Composition

Blood:

• Study of blood is Hematology.
•  It is a large connective tissue containing plasma.
• pH of blood is 7.35/ 7.45.
• Volume of blood in human body is 4.5 liters to 5.0 liters.

Functions of Blood:

• It acts as a transporting agent of Nutrients.
• Helps in Regulation of B.P, Body temperature.
• Coagulation factor present in blood helps in healing of wounds. 
• Provides raw materials to all the glands.

Composition of Blood:

Plasma:

• Plasma contains 90% of water, 10% of inorganic and organic substances which is present in pale yellow fluid part blood.

Organic substances: Amino acids, fats, carbohydrates, hormones Etc.

Inorganic substances: Bicarbonates, sodium, calcium and plasma proteins like Albumin, Globulin, Fibrinogen, Lipo Proteins. 

When the blood allows coagulation it forms a lite pale yellow colour fluid is known as Serum.

                            Serum = Plasma-Blood clotting

                            Plasma = Serum + Clotting Factor

1)RBC :

• RBC is a component of blood present in mammals.
• They are circular, biconcave, anucleated.
• Lifespan of RBC is 120 Days.
• RBC in mammals are in the form of Rolls of Coins.
• Formation takes place in Liver and spleen.
• Production happens in Bone marrow. 

2)WBC :

• They are nucleated Ameboid cells which is large in size and life span is less than RBC.
• They are formed in spleen and liver.
• They act as police men to human body by protecting body from bacterial infections.
• They are capable of engulfing micro organisms with pseudopodia this process is called phagocytosis.
• WBC's are further classified into three types:
  

 Granulocytes:

                              These Granulocytes contains large amount of granules in cytoplasm and form about 70% of leukocytes, they are large cells that are divided into many parts.

a)Basophils:

• The granules in cytoplasm are stained with a basic dye hematoxylin and it gives blue colour.
• Each basophil is about 10µm diameter.
• They increase in number during inflammatory reactions & supplements the function of mast cells when needed.

b)Eosinophils:

• The granules in cytoplasm are stained with acidic dye and gives Red colour.
• Eosinophils are bilobed and it constitute about 2-3% of total WBC.
• Size of eosinophil is 12µm.
• They play a role in allergic reactions by increasing their number.

c)Neutrophils:

• They are stained with neutral dyes.
• They constitute 67% of the total WBC and are of a size 10µm in diameter.
• Nucleus is multilobed.
• These are active phagocytic cells.

Agranulocytes:

• In these agranulocytes granules are absent in cytoplasm. 
• They have a regular nucleus and is not lobed.
• They are further divided into 2 types

Lymphocytes:

• They constitute about 30% of the total leucocytes.
• These are further divided

a) Large lymphocytes:

• These have small cytoplasm and have large dense round nucleus.
• Diameter of the cell is 12µm & comprise 2-3% of the agranulocytes.

                       Eg: Natural Killer Cells

b) Small lymphocytes:

• The cytoplasm is abundant and have smaller nucleus.
• Diameter of the cell is 8µm & comprise larger number of agranulocytes.

                      Eg: T-cells & B-cells.

Monocytes:

• They are largest, motile phagocytes and constitute about 5.3% of the leukocytes. 
• They have diameter of 15µm with a large kidney shaped nucleus.
• They differentiate into either macrophages or dendritic cells when they enter into connective tissue.
• They are produced in the lymphatic system and engulf bacteria and cellular debris.

3)Blood Platelets:

• These are colourless, non nucleated, round or oval shaped.
• No of platelets per mm^3 of blood is about 2.5 Lakhs to 4 Lakhs.
• They are formed from megakaryocytes produced in the red bone marrow by fragmentation.
• The average lifespan of blood platelets is about 5-9 Days.