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

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?

    <p>Transmural pressure changes</p> Signup and view all the answers

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

    <p>Affects small arteries and arterioles, not larger upstream arteries.</p> Signup and view all the answers

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

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

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

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

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

    <p>Oxygen</p> Signup and view all the answers

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

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

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

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

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

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

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

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

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

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

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

    <p>Endothelin</p> 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?

    <p>Increased carbon dioxide levels in the cerebral circulation</p> 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?

    <p>Vasopressin (ADH)</p> 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?

    <p>Histamine</p> Signup and view all the answers

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

    <p>Increased potassium levels</p> Signup and view all the answers

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