Term
| What are the two aspects surrounding the vascular supply to the kidney? |
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Definition
1. Glomerular - Involves filtration of fluid and solute.
2. Tubular - Concerned with how th ematerials that are reabsorbed in the tubules get back into the systemic circulation |
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Term
| How much blood flow does the kidney receive? |
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Definition
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Term
| Where are the majority of nephrons located? |
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Definition
| 85% are located in the cortex |
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Term
| Where is the blood flow rate the highest in the kidney? |
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Definition
| In the cortex, then the outer medulla, then the inner medulla |
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Term
| Is the medulla hyper or hypo-osmotic? Why? |
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Definition
| The medulla is hyperosmotic due to the fact that the osmotic pressure is very high. The osmotic pressure is kept high by limiting the amount of blood flow through the area. Too much blood flow per unit time will cause the movement of solute from the interstitial space into the blood plasma and then out of the kidney and will wash out the medullary gradient |
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Term
| What is the blood flow in the renal medulla proportional to? |
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Definition
| The flow through the loop of henle and the collecting ducts |
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Term
| What is a substance used for examining clearance rate? |
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Definition
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Term
| What is the vasa rectae? What type of nephrons are they found in? |
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Definition
Only found in juxtamedullary nephrons!
They are parrallel loops that exist as a counter-current exchange mechanism as they are closely applied to the juxtamedullary nephron's loop of henle |
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Term
| What do the peritubular capillaries do? |
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Definition
| 1. They can return materials to the body which were reabsorbed by the tubules or they can provide materials to the tubules for secretion. |
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Term
| Extrinsic Control of renal blood flow of the Renal System |
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Definition
| Sympathetic NS regulates the extrinsic control. Catecholamines constrict afferent and efferent arterioles. Serotonin and ADH also constrict. Kinins, ANF, and some prostaglandins dilate |
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Term
| Intrinsic control of renal blood flow |
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Definition
| Myogenic theory - cells respond to stretch in the walls of the afferent arterioles. When BP drops below a certain threshold, the lack of tension on the walls causes increased flow. Above the threshold (80 mmHg) tension is exerted against the walls, causing them to constrict. Only a slight decrease in the diameter can cause a significant increase in resistance. |
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Term
| How does the juxtaglomerular apparatus autoregulate renal blood flow? |
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Definition
| The early portion of the DCT makes contact in the glomerulus where the afferent and efferent arterioles enter and exit. Macula densa of the DCT make contact with the granular cells of the afferent arteriole. Granular cells release renin, adenosine, and vasoconstrictor prostaglandins into the interstitium around the afferent arterioles. Ultimately, this system controls the amount of fluid coming from the loop of henle. Overall, the juxtaglomerular apparatus is responsible for controlling the hydrostatic pressure in the afferent arteriole. |
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Term
| What and how is renin release stimulated? |
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Definition
| The granular cells of the afferent arterioles are sensitive to stretch. When the BP drops to a certain level, they release renin directly into the vascular system. This creates angiotensin I and II, vasoconstriction in many peripheral beds, and the resultant release of aldosterone from teh adrenal cortex. This reflex acts to retain Na and thereby water in the body, also increasing BP. |
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