Chapter 20, Problem 1DYB

Summary Introduction

Concept introduction: Capillaries are small narrow tubules that form a network between arterioles and venules. They are the smallest blood vessels in the body. Continuous capillaries, fenestrated capillaries, and sinusoid capillaries are the three types of capillaries.

Answer to Problem 1DYB

Correct answer: Sinusoid capillaries are the main type of capillaries around the brain and are not a characteristic of capillary. Hence, the correct answer is option b.

Explanation of Solution

Reason for the correct answer:

Sinusoid capillaries are not found near the brain. The sinusoid capillaries are found in the red bone marrow, liver, spleen, and some endocrine gland. Hence, sinusoid capillary found near the brain is not a correct characteristic of a capillary.

Option b. is given as “Sinusoid capillaries are the main type of capillaries around the brain”.

Hence, the correct answer is option b.

Reasons for incorrect answers:

Option a. is given as “Fenestrated capillaries allow larger amounts of materials to be exchanged”.

Fenestrated capillaries are permeable and are used to filter, release, and absorbe large material or proteins. Hence, Option a. is incorrect.

Option c. is given as “Capillaries often are arranged in a capillary bed that is supplied by an arteriole”.

Capillaries form a capillary bed, which is a network of capillaries, between an artery and a vein and is present in every region of the body. Hence, Option c. is incorrect.

Option d. is given as “The capillary wall consists of an endothelium and basement membrane only; there is no subendothelial layer”. The walls of capillary are made up of a single layer of endothelial cells. Hence, Option d. is incorrect.

Hence, options a., c., and d. are incorrect.

Conclusion

Sinusoid capillaries are found in the red bone marrow, liver, spleen, and some endocrine gland, but they are not found near the brain.