Question

What is the function of
a) Platelets
b) Haemoglobin in our body?

Answer 1

Hint: Blood is an example for specialised connective-tissue in our body. It is an example of fluid connective tissue as it is made up of a fluid matrix called plasma. It also contains several solid elements that are suspended in the plasma and they are called formed elements.

Complete answer: a) The blood is the major circulatory fluid present in our body. Along with the heart and blood vessels, it forms the blood vascular system. The blood contains several formed elements that include both blood cells and blood platelets. RBC and WBC are the major blood cells in our body. Blood platelets are part of formed elements in our blood. They are also called thrombocytes. Platelets arise from cells called megakaryocytes that are present in the bone marrow. They have an important role in blood coagulation as they release several chemicals called clotting factors. A decrease in the total count of platelets may cause several clotting disorders and can result in excessive blood loss from our body.
b) Erythrocytes or red blood cells are the major blood cells in our body. The structure of RBC is different as mammalian RBC are non-nucleated cells and are biconcave in shape. There are certain invertebrates that have nucleated RBC. The red colour of RBC is contributed by the presence of a respiratory pigment called haemoglobin. It is a tetramer that contains four subunits and helps in the transport of oxygen in our body. It is a conjugated protein that consists of Heme and a protein named Globin.

Note: Each haemoglobin molecule has the capacity to carry a maximum of four molecules of oxygen from lungs to tissues. Its saturation with oxygen is dependent on the partial pressure of oxygen. The curve we get by plotting percentage saturation of haemoglobin with oxygen and the partial pressure of oxygen is called oxygen dissociation curve.