Renal physiology
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Questions and Answers

What is the primary physiological effect of loop diuretics in the body?

  • Increase blood volume
  • Decrease blood pressure (correct)
  • Stimulate aldosterone release
  • Increase glomerular filtration rate

    • Which cells release renin in response to decreased NaCl concentration?

  • Macula densa cells
  • Podocytes in the efferent glomerulus
  • Granular cells in the arteriole (correct)
  • Juxtaglomerular cells

    • What is the primary function of angiotensin II in the body?

  • Promote aldosterone release (correct)
  • Inhibit vasopressin release
  • Decrease arteriolar vasoconstriction
  • Suppress thirst sensation

    • How does dehydration purposefully regulate glomerular filtration rate (GFR) in the body?

    <p>By increasing fluid absorption back into the bloodstream</p> Signup and view all the answers

    Which physiological response occurs when there is a reduction in blood volume detected by baroreceptors?

    <p>Arteriolar vasoconstriction</p> Signup and view all the answers

    What is the mechanism of action of loop diuretics such as furosemide?

    <p>Block NKCC2 cotransporters</p> Signup and view all the answers

    How does angiotensin II contribute to maintaining blood pressure in the body?

    <p>Increases aldosterone release</p> Signup and view all the answers

    What is the role of baroreceptors in regulating blood pressure?

    <p>Detect changes in arterial blood pressure</p> Signup and view all the answers

    What is the primary driving force behind glomerular filtration?

    <p>Glomerular capillary blood pressure</p> Signup and view all the answers

    What cells in the tubuloglomerular feedback mechanism monitor sodium chloride levels?

    <p>Macula densa cells</p> Signup and view all the answers

    What is the role of adenosine in the tubuloglomerular feedback mechanism?

    <p>Constricts the afferent arteriole</p> Signup and view all the answers

    What is the role of the myogenic mechanism in intrinsic control of blood pressure?

    <p>Constricts the afferent arteriole</p> Signup and view all the answers

    What is the effect of nitric oxide on the tubuloglomerular feedback mechanism?

    <p>Dilates the afferent arteriole</p> Signup and view all the answers

    What is the effect of high blood pressure on glomerular filtration rate (GFR)?

    <p>Increases GFR</p> Signup and view all the answers

    What is the role of Bowman's capsule hydrostatic pressure in glomerular filtration?

    <p>Opposes filtration</p> Signup and view all the answers

    What are the three forces that determine the glomerular filtration rate (GFR)?

    <p>Glomerular capillary blood pressure, plasma colloid osmotic pressure, Bowman's capsule hydrostatic pressure</p> Signup and view all the answers

    Explain the role of myogenic mechanism in intrinsic control of blood pressure.

    <p>The myogenic mechanism involves the contraction or dilation of arterioles in response to changes in blood pressure, helping to regulate blood flow and pressure within the kidneys.</p> Signup and view all the answers

    How do the macula densa cells contribute to the tubuloglomerular feedback mechanism?

    <p>Macula densa cells monitor NaCl levels and respond to high blood pressure by releasing ATP and adenosine, signaling arteriole cells to constrict and reduce blood flow.</p> Signup and view all the answers

    Describe the role of granular cells in the tubuloglomerular feedback mechanism.

    <p>Granular cells in the efferent arteriole release renin in response to decreased NaCl concentration, initiating the renin-angiotensin-aldosterone system to regulate blood pressure.</p> Signup and view all the answers

    How does the tubuloglomerular feedback mechanism utilize nitric oxide?

    <p>Macula densa cells can secrete nitric oxide as a vasodilator to increase blood flow in response to certain stimuli, contributing to the regulation of GFR.</p> Signup and view all the answers

    Explain the role of granular cells in the renin-angiotensin-aldosterone system and how their activity is regulated.

    <p>Granular cells release renin in response to decreased blood pressure or decreased NaCl concentration detected by baroreceptors and macula densa cells respectively.</p> Signup and view all the answers

    Describe the mechanism by which loop diuretics such as furosemide impact the renal system.

    <p>Loop diuretics block the NKCC2 cotransporters in the ascending limb of the loop of Henle, leading to decreased reabsorption of sodium and water, ultimately increasing urine output.</p> Signup and view all the answers

    Explain how the renin-angiotensin-aldosterone system counteracts stimuli that trigger renin release.

    <p>Angiotensin II, produced as a result of renin activity, causes arteriolar vasoconstriction, aldosterone release, thirst, and vasopressin release, all working to counteract the initial stimuli.</p> Signup and view all the answers

    Discuss the significance of counter current multiplication in the kidney's nephron function and its relationship to loop diuretics.

    <p>Counter current multiplication allows for concentration of solutes in the medulla, while loop diuretics disrupt this process by inhibiting NKCC2 cotransporters, impacting the kidney's ability to concentrate urine.</p> Signup and view all the answers

    How does dehydration purposely regulate glomerular filtration rate (GFR) and what physiological responses are triggered to maintain homeostasis?

    <p>Dehydration reduces blood volume and activates mechanisms like sympathetic activity, renin-angiotensin-aldosterone system, and vasoconstriction to decrease GFR and conserve water in the body.</p> Signup and view all the answers

    In the presence of dehydration, the release of renin by granular cells is triggered by a decrease in NaCl detected by macula densa cells.

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

    Loop diuretics work by blocking the NKCC2 cotransporter, leading to an increase in blood volume and subsequently increasing blood pressure.

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

    Angiotensin II causes arteriolar vasodilation and a decrease in aldosterone release.

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

    The myogenic mechanism is part of the extrinsic control of glomerular filtration rate (GFR).

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

    In response to reduced blood volume detected by baroreceptors, the sympathetic activity decreases, leading to arteriolar vasodilation and an increase in GFR.

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

    where is aldosterone released from?

    <p>adrenal cortex</p> Signup and view all the answers

    what does aldosterone do?

    <p>increases Na+ reabsorption</p> Signup and view all the answers

    what causes renin to be released? and what system releases it?

    <p>RAAS= renin-angiotensin-aldosterone system Renin released by granular cells</p> <ol> <li>changes in baroreceptor activity by granular cells</li> <li>macula densa cells detect decrease in NaCl which signals more renin</li> <li>granular cells innervated by SNS which stimulates more renin release.</li> </ol> Signup and view all the answers

    Study Notes

    Glomerular Filtration Rate (GFR)

    • GFR is the amount of blood that can be filtered from the glomerulus into the tubule.
    • It is a passive process due to fluid dynamics.
    • Glomerular capillaries are more permeable than other capillaries.

    Factors Affecting GFR

    • Glomerular capillary blood pressure (favours filtration) due to larger afferent compared to efferent arteriole.
    • Plasma-colloid osmotic pressure (opposes filtration) due to a mixture of proteins.
    • Bowman's capsule hydrostatic pressure (opposes filtration) due to physical pressure exerted by liquid.
    • Net filtration pressure (favours filtration) is the result of the three forces.

    Intrinsic Control of GFR

    • Intrinsic control is from within the kidneys.
    • Myogenic mechanism: baroreceptors in the arteriole contract or dilate.
    • Tubuloglomerular feedback: specialized cells called Juxtaglomerular apparatus in the DCT and afferent arteriole.
    • Granular cells in the efferent arteriole and macula densa cells in the DCT monitor NaCl.
    • High BP leads to increased blood flow, increased filtrate, and more NaCl.
    • Macula densa cells send a paracrine message to arteriole cells by releasing ATP and adenosine, causing constriction and decreased blood flow.
    • Another level of control is when macula densa cells secrete nitric oxide (vasodilator).

    Extrinsic Control of GFR

    • Extrinsic control overrides intrinsic control.
    • Dehydration leads to reduced blood volume, reduced arteriole blood pressure, and increased sympathetic activity.
    • This increases BP, arteriole vasoconstriction, and decreases GFR, filtrate, and urine production.
    • More fluid is absorbed back into the bloodstream.

    Renin-Angiotensin-Aldosterone System (RAAS)

    • RAAS is activated in response to decreased blood pressure and NaCl.
    • Granular cells in the arteriole release renin due to baroreceptors activity and macula densa cells detecting decreased NaCl.
    • Renin ultimately causes the release of angiotensin II, which leads to:
      • Arteriolar vasoconstriction
      • Vasopressin release
      • Aldosterone release
      • Thirst
      • All of these counteract the stimuli that led to renin release.

    Loop Diuretics

    • Loop diuretics are used to treat oedema associated with heart, liver, and renal failure.
    • They treat hypertension by decreasing blood volume and BP.
    • They help to urinate more frequently by blocking the NKCC2 cotransporter.
    • Counter current is the descending and ascending limb being next to each other, meaning fluid goes in opposite directions.
    • Loop diuretics block the NKCC2 cotransporter.

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    Related Documents

    Renal Physiology.docx

    Description

    Learn about glomerular filtration rate (GFR) and the forces that determine it, including glomerular capillary blood pressure, plasma colloid osmotic pressure, and Bowman's capsule hydrostatic pressure. Understand the passive process of filtration due to fluid dynamics in the kidney's glomerulus.

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