Question

What are the cells lining the blood capillaries?
A) Endothelial cells
B) Oxyntic cells
C) Parietal cells
D) Haemocytes

Answer 1

Hint:Capillaries are the smallest blood vessels in our body. They are just one cell thick. Main function of the capillaries is to transfer the oxygen and nutrients from the blood circulation to body tissues and take away waste products like Carbon dioxide from the tissues for exhalation by lungs.

Complete answer:
All blood vessels in the body are lined by a single layer of endothelial cells. They act as an important barrier between the blood vessels and the body tissues by regulating the exchange of substances between them.

Let us analyse the options to find the correct answer.
>Option A: Endothelial cells line the blood capillaries. Hence, this is the correct option. Entire vascular system ranging from heart to the capillaries is lined by endothelial cells which shows that they play a pivotal role in maintaining a regulated blood flow.
>Option B and C : Oxyntic cells also known as Parietal cells are epithelial cells which line the walls of the stomach. They are involved in production of gastric acid i.e. Hydrochloric acid. Hence, they are incorrect options.
>Option D: Haemocytes are immune cells present in the hemolymph of invertebrates like insects. Hence, this is an incorrect option.

Thus, the correct answer is option (A) Endothelial cells.

Note:
>Blood vessels like capillaries, arteries and veins are derived from mesoderm during embryonic development.
>Tissues depend on endothelial cells for blood supply which form the lining of the blood vessels.
>By the process of cell migration endothelial cells perform the functions of tissue growth and repair.
>Angiogenesis is the formation of new blood vessels as capillaries from pre existing vessels.
>Endothelial cells form the most important blood-brain barrier between blood vessels and brain.