(a) Draw a labelled diagram of the human heart.
(b) What is the use of platelets in the maintenance of human beings?
(c) Which respiratory pigment is found in red blood corpuscles found in human blood?

Hint: If not for thrombocytes an organism may bleed to death. The respiratory pigment found in red blood corpuscles contains iron. Its average plasma content in a normal adult healthy human being is about 14 to 16 g/dl.

Complete answer:
a) Human heart



B) Platelets play an important role in blood clotting and
C) The respiratory pigment found in red blood corpuscles in human blood is haemoglobin.
Blood mainly consists of formed elements (blood cells) and plasma (liquid portion of blood). Plasma consists of serum and fibrinogen. The formed elements of blood cells are RBC ( erythrocytes), WBC (leukocytes) and platelets (thrombocytes).
Let's study in detail about platelets.
Platelets or thrombocytes are small, colourless and non-nucleated cells. They are believed to be fragments of the cytoplasm. Platelets have a lot of functions as we will study below.
- Platelets play a part in clot retraction.
- They accelerate haemostasis.
- Thrombocytes also play a vital role in the repair of ruptured blood vessels.
- Platelets also participate in the body’s defence mechanism.

Additional Information:
- Haemoglobin forms 95% of the dry weight of RBC and 30 to 34% of wet weight.
- The molecular weight of haemoglobin is 68,000.

Note:
-The average haemoglobin content in a normal healthy adult male is 15 g/dl.
- The average haemoglobin content in a normal healthy adult female is 14.5 g/dl.
- Hemostasis is a process of stopping blood loss.