Human Blood

• Blood is a fluid connective tissue.
• The quantity of blood in the human’s body is 7% of the total weight.
• This is a dissolution of base whose pH value is 7.4.
• There is an average of 5-6 litres of blood in human body.
• Female contains half litre of blood less in comparison to male.
• Blood consists of two parts:- (A) Plasma (B) Blood Corpuscles

(A) Plasma

• This is the liquid part of blood. 60% of the blood is plasma. Its 90% parts is water, 7% protein, 0.9% salt and 0.1% is glucose. Remaining substances are in a very low quantity.
• Function of plasma – Transportation of digested food, hormones, excretory product etc. from the body takes place through plasma.
• Serum – When Fibrinogen & Protein is extracted out of plasma, the remaining plasma is called serum.

(B) Blood Corpuscles (40% part of the blood)

This is divided into three parts:

1.Red Blood Corpuscles (RBC)

• Red Blood Corpuscles (RBC) of a mammal is biconcave
• There is no nucleus in it. Exception – Camel and Lama.
• RBC is formed in Bone Marrow( At the embroynic stage its formation takes place in liver.)
• Its life span is from 20 days to 120 days.
• Its destruction takes place in liver & spleen. Therefore, liver is called grave of RBC.
• It contains haemoglobin, in which haeme iron containing compound is found and due to this the colour of blood is red.
• Globin is a proteinous compound which is extremely capable of combining with oxygen and carbon dioxide.
• The iron compound found in haemoglobin, is haematin.
• The main function of RBC is to carry oxygen to all cells of the body and bring back the carbon dioxide.
• Anaemia disease is caused due to the deficiency of haemoglobin.
• At the time of sleeping RBC is reduced by 5% and people who are at the height of 4200 metres RBC increases by 30% in them.

2. White Blood Corpuscles (WBC) or Leucocytes

• In shape and constitution this is similar to Amoeba.
• Its formation takes place in Bone Marrow, lymph node and sometimes in liver and spleen.
• Its life span is from 1 to 2 days.
• Nucleus is present in the White Blood Corpuscles.
• Its main function is to protect the body from the disease. The ratio of RBC and WBC is 600:1.

3. Blood Platelets or Thrombocytes 

• It is found only in the blood of human and other mammals.
• There is no nucleus in it.
• Its formation takes place in Bone marrow.
• Its life span is from 3 to 5 days.
• It dies in the Spleen.
• Its main function is to help in clotting of blood.

Function of Blood:

• To control the temperature of the body and to protect the body from diseases.

Clotting of blood.

• Transportation of oxygen, Carbon dioxide, digested food, conduction of hormones etc.
• To help in establishing coordination among different parts.

Blood Group of Human

• Blood group was discovered by Lansteiner in 1900.
• For this, he was awarded with Nobel Prize in the year 1930.
• The main reason behind the difference in blood of human is the glyco protein which is found in Red Blood Corpuscles called antigen. Antigen are of two types- Antigen A and Antigen B.
• On the basis of presence of Antigen or Glyco Protein, there are four group of blood in human:
• That contains Antigen A – Blood Group A.
• That contains Antigen B– Blood Group B.
• That contains both the Antigen A and B – Blood Group AB.
• That contains neither of the Antigens- Blood Group O.
• An opposite type of protein, is found in blood plasma. This is called antibody. This is also of two types- Antibody “a” and Antibody “b”.
  Blood Group O is called the Universal Donor because it does not contain any antigen.
  Blood Group AB is called Universal Receptor because it does not contain any antibody