Local and Humoral Control of Tissue Blood Flow NRAN 80413 Spring 2024 Quiz

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What happens when a blood vessel relaxes?

It constricts and decreases blood flow.

It stops blood flow completely.

It remains unchanged.

It dilates, allowing more blood and oxygen to be supplied. (correct)

What is the purpose of autoregulation in the context of blood flow?

To increase blood vessel diameter.

To maintain or rapidly return to normal blood flow following abrupt changes in arterial pressure. (correct)

To decrease smooth muscle contraction.

To decrease oxygen supply to tissues.

Which theory suggests that excess oxygen or other nutrients cause increased smooth muscle contraction?

Neurohumoral Theory

Stretch-induced Theory

Metabolic Theory (correct)

Myogenic Theory

According to the Myogenic Theory of autoregulation, what initiates the contraction or relaxation of vascular smooth muscle?

Transmural pressure changes Signup and view all the answers

What is the effect of locally mediated vasodilation according to Levy's concept?

Affects small arteries and arterioles, not larger upstream arteries. Signup and view all the answers

In the context of blood flow, what is reactive hyperemia?

An increase in blood flow post-occlusion to several times the baseline value. Signup and view all the answers

Which of the following statements accurately describes the role of smooth muscle in regulating blood flow?

Variation in smooth muscle contraction allows preferential distribution of blood flow and control of total peripheral resistance. Signup and view all the answers

Which of the following substances is NOT involved in pharmacomechanical coupling, leading to smooth muscle contraction?

Oxygen Signup and view all the answers

According to the vasodilator theory of local blood flow regulation, what causes the release of vasodilator substances?

An increase in metabolism or a decrease in supply of oxygen or other nutrients Signup and view all the answers

Which of the following statements accurately describes the oxygen lack theory of local blood flow regulation?

In the absence of adequate oxygen, smooth muscle is unable to maintain contraction, leading to vasodilation. Signup and view all the answers

Which of the following statements accurately compares smooth muscle contraction and skeletal muscle contraction?

Smooth muscle contraction develops very slowly, while skeletal muscle contraction develops rapidly. Signup and view all the answers

Which of the following statements is true regarding the baseline tone of resistance vessels?

The resistance vessels exhibit partial constriction at baseline, allowing for both vasodilation and further vasoconstriction. Signup and view all the answers

What is the primary factor responsible for baseline vascular tone in the absence of nervous system input?

Myogenic activity in response to the stretch imposed by blood pressure Signup and view all the answers

Which of the following substances is released from damaged endothelial cells and produces local vasoconstriction to reduce bleeding?

Endothelin Signup and view all the answers

Which of the following factors is responsible for the vasodilation observed in cerebral blood vessels in response to increased carbon dioxide levels?

Increased carbon dioxide levels in the cerebral circulation Signup and view all the answers

Which of the following substances is released from the posterior pituitary and functions to increase both vasoconstriction and tubular reabsorption of water?

Vasopressin (ADH) Signup and view all the answers

Which of the following substances is an arteriolar dilator and increases capillary permeability following release from inflamed or damaged tissues?

Histamine Signup and view all the answers

Which of the following factors leads to vasodilation in the long-term regulation of blood flow?

Increased potassium levels Signup and view all the answers