Question

What happens if blood platelets are absent?

Answer 1

Blood is a fluid present in all animals. It is composed of blood cells that remain suspended in a fluid plasma. Plasma comprises primarily water and contains ions, proteins, minerals, etc.
The cells that constitute blood are of three types, namely, the Red Blood Cells or RBC, the White Blood Cells or WBC and the Platelets or Thrombocytes.

Complete answer:
Blood consists of three types of blood cells or blood corpuscles that remain suspended in the blood plasma. Each type of blood cell performs a particular function and is indispensable to the proper functioning of a living organism.

The Red Blood Cells or RBC or Erythrocytes are non-nucleated cells that carry oxygen from the lungs to different parts of the body. RBC(s) are responsible for the red colour of the blood because of the presence of an iron containing compound called haemoglobin.
The White Blood Cells or WBC or Leukocytes are nucleated cells that function to protect the body through a process called phagocytosis.

Platelets or Thrombocytes are non-nucleated cells that help in blood clotting or blood coagulation. When we get injured, the blood vessels are ruptured and as a result there is loss of blood. The blood platelets, at such times, form a mesh like structure at the site of injury to stop the blood flow. This process takes through the following steps:
- The platelets release a chemical called prothrombin when it senses an injury.
- Prothrombin, in turn, activates thrombin.
- Thrombin activates fibrinogen, which in turns causes a protein called fibrin (present in blood) to polymerize and form a mesh like structure at the site of injury. This mesh like structure is the blood clot.
- Formation of blood clot at the site of injury or wound prevents further blood loss.
- Once the loss of blood stops, the clot hardens and new cells start to grow and repair the site of injury.
- Slowly, the clot is dissolved by an enzyme called plasmin.

Therefore, without the presence of platelets, we will not be able to form blood clots. Excessive loss of blood even from a small wound or injury can lead to death. That is why, it is important to maintain a normal platelet count in our blood.

Note: Blood clotting is the process by which our body reacts to blood vessel ruptures and prevents excessive loss of blood. This is achieved by the thrombocytes or platelets present in blood. However, excessive amounts of platelets in blood can give rise to conditions like thrombocytosis. Therefore, it is very important to have a normal platelet count in our body, which is around 150,000 to 400,000 per microliter of blood in adults.