13.4 Lecture Blood Flow and Oxygen Availability

13.4 Lecture Blood Flow and Oxygen Availability

Explore how blood flow adapts to meet tissue needs, with kidneys receiving 1100 ml/min and active muscles 750 ml/min. Understand acute control via vasodilation/constriction and long-term adjustments in blood vessel number/size. Examine the vasodilator theory and oxygen demand theory, linking oxygen availability to blood flow regulation.

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Answer from memory first, then review the rationales and revisit weak areas from this set.

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Quiz24 Questions
Flashcards19 Cards
Study Notes1 Note
Podcast1 Episode

List of Questions24 questions
  1. Question 1
    • Increased oxygen levels directly stimulate the release of vasodilators, promoting increased blood flow to tissues.
    • Oxygen is converted into vasodilator substances, such as adenosine and carbon dioxide, that cause local vasodilation.
    • Elevated oxygen concentrations cause the precapillary sphincters to close, redirecting blood flow to more oxygen-deprived areas.
    • Reduced oxygen availability leads to decreased contraction of arteriolar muscles, resulting in vasodilation and increased blood flow.
  2. Question 2
    • a sustained decrease in blood flow following a period of increased metabolic activity.
    • a temporary increase in blood flow to an area after a period of restricted blood supply.
    • a prolonged vasodilation caused by the accumulation of vasodilator substances.
    • a consistently elevated blood flow due to chronic inflammation.
  3. Question 3
    • Vasoconstriction occurs which helps to maintain relatively constant blood flow.
    • Blood flow increases linearly with the increase in arterial pressure.
    • Pre-capillary sphincters fully open, leading to a dramatic increase in blood flow.
    • Vasodilation occurs due to increased metabolic demand of the surrounding tissues.
  4. Question 4
    • stimulating the release of nitric oxide to enhance blood flow to the glomerulus.
    • constricting the efferent arterioles to reduce blood flow and filtration.
    • causing vasodilation of the afferent arterioles to increase blood flow and filtration.
    • constricting the afferent arterioles to decrease blood flow and filtration.
  5. Question 5
    • It directly stimulates vasoconstriction by activating endothelial cells.
    • It promotes vasodilation by converting cyclic GMP to cyclic GTP, leading to smooth muscle relaxation.
    • It acts as a vasoconstrictor in response to increased shear stress on the endothelium.
    • It promotes vasodilation by converting cyclic GTP to cyclic GMP, leading to smooth muscle relaxation.
  6. Question 6
    • It promotes vasodilation to facilitate tissue repair and reduce inflammation.
    • It acts as a powerful vasoconstrictor to prevent excessive bleeding.
    • It enhances the effects of nitric oxide to maintain vascular tone.
    • It inhibits angiogenesis to prevent the formation of new blood vessels.
  7. Question 7
    • Hormonal signals that promote or inhibit blood vessel growth
    • Minimum level of blood flow required to maintain tissue viability
    • Average metabolic need of the tissue over a long period
    • The maximum level of blood flow needed, even if only intermittently
  8. Question 8
    • By directly stimulating the heart to increase cardiac output and lower blood pressure.
    • By acting on many arterioles simultaneously, increasing total peripheral resistance, and decreasing sodium and water excretion by the kidneys.
    • By causing vasodilation and increasing sodium excretion by the kidneys.
    • By promoting the release of nitric oxide, leading to widespread vasodilation.
  9. Question 9
    • Potent vasodilation and increased sodium excretion.
    • Significant vasoconstriction and increased water reabsorption in the renal tubules.
    • Mild vasodilation and decreased capillary permeability.
    • Increased capillary permeability but minimal effect on overall vascular tone.
  10. Question 10
    • They primarily affect capillary permeability, not arteriolar diameter.
    • They are overridden by the effects of vasopressin and angiotensin II.
    • They are rapidly inactivated in the blood, limiting their duration of action.
    • They are only produced during allergic reactions and have minimal overall impact.
  11. Question 11
    • They primarily control long-term adjustments in blood vessel size and number.
    • They override the influence of the autonomic nervous system and hormonal control.
    • They only play a significant role during periods of intense physical activity.
    • They fine-tune blood flow to match the specific metabolic needs of the tissue.
  12. Question 12
    • They act as a secondary pump to assist the heart in delivering blood to the tissues.
    • They produce vasodilators that maintain the dilation of blood vessels in the tissues
    • They control the overall arterial pressure by diverting blood to different vascular beds.
    • They regulate blood flow into individual capillaries based on the nutritional needs of the tissue.
  13. Question 13
    • Vasodilation and constriction of arterioles in response to hormonal signals
    • Alterations in the number and size of blood vessels over days, weeks, or months
    • Rapid changes in cardiac output to meet immediate tissue needs
    • Immediate adjustment of blood flow by the autonomic nervous system
  14. Question 14
    • Stretching of blood vessels causes smooth muscle to contract, reducing blood flow.
    • Changes in oxygen demand stimulate the release of substances that cause vasodilation.
    • Increased blood flow washes out vasodilators, leading to vasoconstriction.
    • Metabolic activity produces vasodilators that override myogenic responses.
  15. Question 15
    • Decrease in oxygen concentration
    • Increase in carbon dioxide or hydrogen ion concentration
    • Activation of sympathetic nervous system
    • Release of nitric oxide from endothelial cells
  16. Question 16
    • Direct vasoconstriction through neural pathways and vasodilation via hormonal pathways.
    • Vasodilation through beta receptors and vasoconstriction through alpha receptors.
    • Vasodilation through local release and vasoconstriction via systemic release.
    • Vasoconstriction through nerve endings in tissues and through secretion from the adrenal medulla.
  17. Question 17
    • It acts as a powerful vasodilator and increases capillary permeability.
    • It promotes the contraction of smooth muscle cells, leading to vasoconstriction and reduced permeability.
    • It stimulates the release of nitric oxide, causing vasodilation and decreased permeability.
    • It directly inhibits the production of vasodilator substances, limiting blood flow.
  18. Question 18
    • It causes the blocked vessel to regenerate, restoring normal blood flow.
    • It provides an alternative route for blood to reach tissues, compensating for the blockage.
    • It leads to a permanent reduction in blood flow to the affected tissues.
    • It reduces the risk of future blockages in the same vessel.
  19. Question 19
    • In tissues with consistently low metabolic demands.
    • In tissues with chronic hypertension or damaged endothelium.
    • In new tissues, such as in young individuals or cancerous tissue.
    • In old, well-established tissues with a limited capacity for growth.
  20. Question 20
    • Metabolic theory
    • Vasodilator theory
    • Myogenic mechanism
    • Oxygen demand theory
  21. Question 21
    • Auto regulation of blood pressure due to hormonal control
    • Reduced blood flow after prolonged inactivity
    • Increased blood flow in response to activity, such as skeletal muscle usage
    • Compensatory blood flow following a period of ischemia
  22. Question 22
    • Shear stress triggers the release of endothelin, leading to vasoconstriction.
    • Shear stress reduces the sensitivity of blood vessels to vasoconstrictor substances.
    • Shear stress directly constricts blood vessels, reducing blood flow to local tissues.
    • Shear stress stimulates the release of nitric oxide, causing vasodilation.
  23. Question 23
    • Metabolic theory
    • Vasodilator theory
    • Oxygen demand theory
    • Myogenic theory
  24. Question 24
    • Increased pressure reduces the production of vasodilator substances.
    • Increased pressure stretches blood vessels, causing smooth muscle contraction.
    • Excess flow increases oxygen delivery, causing vasodilation.
    • Excess flow washes out vasodilators, causing the arterioles to constrict.
List of Flashcards19 flashcards
  1. Card 1
    HintThink rapid adjustments to blood vessel diameter.Memory TipA cute adjustment for blood vessels
  2. Card 2
    HintGrowth and remodeling over a longer timescale.Memory TipThink of long term growth
  3. Card 3
    HintMetabolic byproducts trigger blood vessel widening.Memory TipMore metabolism, more dilation
  4. Card 4
    HintLack of oxygen leads to blood vessel relaxation.Memory TipNo O2, vessels relax.
  5. Card 5
    HintBlood rushes back after a period of deprivation.Memory TipBlood repays oxygen debt.
  6. Card 6
    HintMore activity, greater blood supply to the muscles.Memory TipActive muscles need more blood.
  7. Card 7
    HintBlood flow stays constant in a range of pressures.Memory TipAuto pilot for blood flow
  8. Card 8
    HintVasodilators get diluted, vessels narrow.Memory TipWashout causes constriction.
  9. Card 9
    HintStretch induces contraction.Memory TipStretch then shrink
  10. Card 10
    HintToo much fluid triggers constriction.Memory TipT.G.F constricts flow.
  11. Card 11
    HintHigh CO2 = vasodilationMemory TipBrain needs O2
  12. Card 12
    HintGas that widens blood vessels.Memory TipNO = more flow.
  13. Card 13
    HintReleased when vessels are damaged.Memory TipEndo stops bleeding
  14. Card 14
    HintNew vessels forming.Memory TipAngio = new vessels
  15. Card 15
    HintHormones that narrow blood vessels.Memory TipEpi constricts
  16. Card 16
    HintIncreases resistance and conserves fluid.Memory TipAngio increases pressure
  17. Card 17
    HintConserves water and constricts vessels.Memory TipKeeps water in, vessels tight.
  18. Card 18
    HintPromote dilation and leakage.Memory TipKinins: leaky dilation.
  19. Card 19
    HintReleased during inflammation and allergies.Memory TipHistamine: Inflammatory dilation.