Monday, October 21, 2019

Human Blood


Human Blood

  • The blood constitutes 7% of the total weight of the human's body.
  • Its pH value is nearly 7.4, so it is considered base in nature.
  • There is an average of 5-6 litres of blood in human body.
  • Blood consists of two parts:- 
    (1) Plasma 
    (2) Blood Corpuscles
(1) Plasma
  • It is the liquid part of blood.
  • It constitutes 60% part of the blood.
  • The plasma has 90% parts is water, 7% protein, 0.9% salt and 0.1% is glucose. 
  • Its main function is to Transport of digested food, hormones, the excretory product from one part of the body to another part of the body.
  • When Fibrinogen & Protein is extracted out of plasma, the remaining plasma is called serum.
(2) Blood Corpuscles
  • It constitutes 40% part of the blood/
This is divided into three parts:
1.Red Blood Corpuscles (RBC)
  • The nucleus is absent from it. Exception - Camel and Lama.
  • It is formed in Bone Marrow (At the embryonic stage its formation takes place in the liver.)
  • Lifespan- 20 days to 120 days.
  • RBCs destruction takes place in spleen so it is called grave of RBC.
  • It contains haemoglobin, in which haeme is iron-containing compound.
  • Due to the presence of haemoglobin 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.
  • Function- 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
  • Its formation takes place in Bone Marrow, lymph node and sometimes in liver and spleen.
  • Lifespan: 5-20 days.
  • The nucleus is present in the WBC.
  • Function- to protect the body from the disease.
  • The ratio of RBC and WBC is 600:1.
  • It consists of Granulocytes and Agranulocytes.
  • Granulocytes consists of Neutrophils, Eosinophils, and Basophils.
  • Agranulocytes consists of lymphocytes and monocytes.
3. Blood Platelets or Thrombocytes 
  • Found only in the blood of human and other mammals.
  • The nucleus is absent in it.
  • Its formation takes place in the Bone marrow.
  • Lifespan- 3 to 5 days.
  • It dies in the Spleen.
  • Function- to help in clotting of blood
Functions of Blood:
  • To control the temperature of the body and to protect the body from diseases.
  • Transportation of oxygen, Carbon dioxide, digested food, conduction of hormones etc.
  • To help in establishing coordination among different parts.



Clotting of blood
  • Following reactions take place during clotting-
    (a) Thromboplastin + Prothrombin + Calcium = Thrombin
    (b) Thrombin + Fibrinogen = Fibrin
    (c) Fibrin + Blood Corpuscles = Clot
  • Vitamin K is helpful in blood clotting.
Blood Group of Human
  • Blood group was discovered by Landsteiner in 1900.
  • For this, he was awarded Nobel Prize in the year 1930.
  • The main reason behind the difference in the blood of the human is the glycoprotein which is found in Red Blood Corpuscles called antigen.
  • Antigen is of two types- Antigen A and Antigen B.
  • On the basis of the presence of Antigen or Glyco Protein, there is 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 Recipient because it does not contain any antibody
  • Heparin is an anti-coagulant which is present in blood which assures smooth blood flow in the vessels.


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