Question

Fenestrated capillaries ________.

A. are not common in endocrine organs and in areas where capillary absorption is an important function
B. are not more permeable than continuous capillaries
C. do not occur in the glomerular capillaries of the kidneys
D. are not found in the brain

Answer 1

D. are not found in the brain

Step-by-step explanation:

Capillaries are the smallest blood vessels. Their wall is made of a single layer of endothelial cells. Continuous capillaries have uninterrupted lining of endothelial cells. Only small molecules like water molecules and ions can pass through them. Fenestrated capillaries on the other hand have 60-80 nm diameter pores in endothelial cells. Some larger molecules like certain types of proteins can diffuse through them.

They are found in tissues which are engaged in extensive molecular exchange with blood like endocrine glands, kidney and small intestine because they are more permeable than continuous capillaries. They are not found in brain because molecular exchange needs to be highly regulated and restricted in brain. Brain has continuous capillaries which form the blood brain barrier.