Question

Mast cells secrete.
a. Serotonin
b. Heparin
c. Histamine
d. All of the above

Answer 1

Mast cells are also called mechanocytes. These are large. Rounded or oval cells that secrete the matrix of connective tissue. These are very similar in structure and function to the basophil cells that are a type of white blood cells.

Complete answer:
Connective tissue is characterized by a gelatinous, highly vascular and sticky matrix that has a variety of cells and two types of fibres. The fibres are loosely arranged in the matrix.

The various types of cells found are:
- Fibroblasts: These are the most numerous and active cell types that form collagen and elastin protein fibre.
- Macrophages: These are large sized and amoeboid cells that act as phagocytes and engulf bacteria, dead cells and other foreign material.
- Mast cells: These are large rounded cells. They secrete heparin, serotonin and histamine.

Heparin is an anticoagulant or blood thinner that helps in preventing the formation of blood clots. It is generally used before surgery for reducing the risk of blood clotting and also used in treatment of heart attacks and unstable angina.

Histamine is a chemical involved in the local immune responses of the body. It also acts as a neurotransmitter of the brain and helps in regulation of physiological function of the gut.

Serotonin is a neurotransmitter that also has another wide variety of functions in the body. It is also called the happy chemical as it modulates mood and contributes to well-being and happiness.

Hence, the correct answer is option (D).

Note: Mast cells are part of the immune system. They play a very important role in the allergy reactions in the body. They also provide defense against pathogens and are involved in wound healing. They are derived from the myeloid stem cell.