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10 Cards in this Set
- Front
- Back
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What are the vasa recta/
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These loops dip into the medullary pyramids alongside the loops of Henle. The descending vasa recta have a non-fenestrated endothelium that contains a facilitated transporter for urea, and the ascending vasa recta have a fenestrated endothelium, consistent with their function in conserving solute.
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The volume of blood in the renal capillaries at any time is 30-40ml. TRUE/FALSE
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TRUE.
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Describe briefly the renal capsule.
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It is thin, but tough. If the kidney becomes edematous, the capsule limits the swelling, and the tissue pressure rises. (renal interstitial pressure).
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In a resting adult, the kidneys receive 1.2- 1.3 of blood per minute, or just under 25% of the cardiac output. TRUE/FALSE
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TRUE. One measures the amount of a given substance taken up per unit time and dividing this value by the areteriovenous difference for the substance across the kidney.
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What is used as an example to measure renal plasma flow?
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By infusing p- aminohippuric acid(PAH) and determining its urine and plasma concentrations.
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When PAH is infused at low doses, 90% of the PAH in arterial blood is removed in a single circulation through the kidney. TRUE/FALSE
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TRUE. One calculates the renal plasma flow by dividing the amount of PAH in the urine by the plasma PAH level, ignoring the level in renal venous blood.
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When the mean systemic arterial pressure is 100mm Hg, the glomerular capillary pressure is about 45mm/Hg. TRUE/FALSE
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TRUE. The pressure in the renal vein is about 4mm/Hg.
Glomerular capillary pressure is about 40% of systemic arterial pressure. |
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Is renal perfusion relatively constant?
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Yes. However, renal autoregulation is present in denervated and in isolated, perfused kidneys, but is prevented by the administration of drugs that paralyze vascular smooth muscle.
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How is renal autoregulation maintained in such conditions?
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It is likely produced in part by a direct contractile response of the smooth muscle of the afferent arteriole to stretch. NO is probably involved.
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What may play a role at low perfusion pressures?
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Angiotensin 11 may play a role by constricting the efferent arterioles, maintaining glomerular filtration. Patients on Ace inhibitors may develop renal failure if they already have poor renal perfusion.
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