Functions and Types of Blood

Blood functions

Blood has the following functions.

1. Transport of Oxygen and Carbon Dioxide

The main medium of transport of blood oxygen is hemoglobin present in red blood particles. Oxyhemoglobin forms a temporary compound that breaks into tissues and releases oxygen and this oxygen received by cells. Similarly, 10 to 23% of the carbon dioxide produced in cells reacts with hemoglobin to form carboxyhemoglobin. This carboxyhemoglobin reaches the lungs and breaks down and releases carbon dioxide.

2. Transport of Nutrients

Nutrients derived from digested food in the digestive system are absorbed by the blood and lymphatic vessels, transported to the liver, and then supplied through the blood to the whole body as per the requirement of the body.

3.Transport of Excretory Substances

Urea ammonia, excretory, etc substances produced due to metabolic activities in the body are first transported through the blood to the liver and then from the liver to the kidneys. Similarly, the carbon dioxide produced as a result of catabolism in cells is carried through the blood plasma to the lungs.

image of blood

4. Regulation of Body Temperature

Blood works to maintain the normal temperature of various parts of the body. It also transmits dead cells to the spleen.

5. Blood Clot Formation

If an injury occurs somewhere in the body, blood forms a clot and prevents blood loss and infection.

6. Isotopic Control of the Internal Environment of the Body

The blood maintains coherence in the pH value of the tissue, ie its physical and chemical conditions.

7. Water Balance

Blood is also helpful in maintaining the balance of water in the body.

8. Prevention from Diseases

When there is an infection of any harmful bacteria or viruses etc. in the body, white blood cells reach there and fight them and protect the body from diseases.

Blood clotting


Blood starts flowing after an injury to any part of the body. After some time the blood stops flowing due to clot formation there.

1: In the Case of Mild Injury

In the case of mild injury, the blood vessels become narrowed due to bleeding. Out of these, the platelets come out and attach to the collagen of the surrounding connective tissues and make plugs. These plugs close the ruptured or severed holes of the blood vessel, which stops the flow of blood, this process is called platelet aggregation.

2: In the Case of Severe Injury

However, in the event of severe injury, these platelets do not stop plug bleeding, so in such a situation, a complex process of blood clotting starts the blood clotting phase, which has the following stages-

Phase I

In this stage, the damaged tissue secretes a substance called thromboplastin and blood platelets from the blood capillaries also dissolve and release a phospholipid. These two substances combine with plasma, calcium ions, and some plasma proteins to form an enzyme called prothrombinase.

Phase II 

In this phase, the prothrombinase enzyme neutralizes the antigen antagonist (heparin) present in plasma in the presence of calcium ion and breaks down the inactive protein called prothrombin into active thrombin and other small peptide chains.

Phase III

At this stage, thrombin acts as an enzyme to induce the synthesis of insoluble protein molecules called fibrin with the help of plasma soluble fibrinogen proteins and many other protein compounds and calcium ions. The long and fine threads of these fibrinous forms on the injury in the form of dense mesh. Blood particles get trapped in this trap and stop the bleeding by forming a clot in 2–4 minutes upon injury. After a while, this clot starts shrinking and a light yellow serum starts coming out of it. This serum
a mixture of fibrinogen and blood-less plasma.

blood clots

Blood groups

Karl Landsteiner discovered the blood group in the year 1902. There are two types of protein antigen and antibody in the blood. Antigens are found in the membrane or surface of red blood particles and antibodies in the plasma and blood is divided into the following classes based on the presence of antibodies and antigen.

Blood Groups


Genotypes Antigens Antibodies Receive/Donate
A AO, AA A b Receive from:  A & O

Donate to: A & AB

B BB, BO B a Receive from:  B & O

Donate to: B & AB

AB AB AB None Receive from:  All

Donate to: AB

O OO None ab Receive from:  Only O

Donate to: All

Rh Factor

In addition to blood groups, Rh-factor is also found in humans in which it is found Rh-positive and in which it is not found, it is called Rh-negative. Rh factor is positive in about 85% of Indians. If the Rh-positive male is married to the Rh-Negative woman, then his offspring die within about half an hour of being born. This disease is called Erythroblastosis Fetalis.


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