Answer:
a) True
Step-by-step explanation:
Capillaries are the smallest blood vessels, they form networks called "capillary beds" that connect arterioles (small arteries) to venules (small veins). It is at the capillaries that the exchange of substances (nutrients and wastes) between the blood and surrounding tissues occurs.
Capillaries' walls consist of a single layer of endothelial cells. There are different types of capillaries according to their morphology:
- Continuous: the wall of this type of capillary is not interrupted
- Fenestrated: found in tissues with high exchange activity such as kidneys, small intestines and endocrine glands; for this, they are very permeable. Fenestrated means "windows" and refers to the multiple pores this type of capillary has.
- Sinusoids: found in the liver, formed between the sinusoids and hepatocytes.