Question

Which of the following statements are true?
A. Arteries have muscular walls that regulate the flow of blood passing through them
B. Arteries contain valves that prevent the flow of blood in the wrong direction
C. Veins have muscular walls that can regulate the flow of blood passing through them
D. Both A and B
E. Both A and C

Answer 1

Hint: ‌Arteries and veins are tubular muscles through which the blood flows in the body. Arteries transport blood from the heart to the rest of the body. Veins push back blood from the body to the heart. Arteries and veins form a complex system of vessels that run throughout the body. The arteries carry oxygenated blood while the veins carry deoxygenated blood (high in carbon dioxide).

Complete answer:
Option A: The arteries are muscular and control the distribution of blood to different parts of the body. The smooth muscle cells of the artery have the ability to contract to decrease the blood flow or relax to increase the amount of blood flow.
Option A is correct.
Option E: This option is correct as statements given in both option A and option C are true.
Option E is correct,
Option B: Arteries do not have valves. They are attached to the heart and have only a huge pushing force. Hence, flow of blood in the wrong direction is not possible.
Option B is incorrect.
Option C: This statement is correct. Veins have smooth muscles called tunica media which regulates the blood flow through vasoconstriction and vasodilation.
Option C is correct.
Option D: This option is wrong because arteries do not have valves. Only veins contain valves to prevent the backflow of blood.
Option D is incorrect.

Therefore the correct answer is option E. Both A and C.

Note:
The blood vessels are made up of three distinct layers or tunics. The first layer also known as tunica intima is the inner lining of endothelial cells that are in contact with the RBC’s. The middle tunic or tunica media is made of smooth muscle and the outermost layer called tunica externa is connective tissue made of collagen and elastic fibres. The smooth muscle layer helps regulate blood flow through vasoconstriction and vasodilation. The connective tissue stretches and supports the blood vessels.