Important Biology Notes on Human Blood For SSC Exams

Blood is a bodily fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. Blood contains antibodies, nutrients, oxygen and much more to help the body work. Let us have a look on the Composition of Human Blood in detail. The post is very important for upcoming Railway Exam and SSC CGL 2017 Exam.

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