phys test 4 review

phys test 4 review - Understand Blood and filtrate flow...

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Understand Blood and filtrate flow through the nephron Filtrate flow: capillaries of renal corpuscle glomerulus bowman's capsule renal tubule: -proximal convoluted tubule -Loop of Henle -distal convoluted tubule -collecting duct Blood Flow: afferent arteriole glomerulus efferent arteriole peritubular capillaries out through kidney venous system *renal veins leave the kidney returning blood through the inferior vena cava Understand how the countercurrent is established. Remember even though you were given the loop of Henle as one unit of the anatomy of the nephron you got to remember that the descending and ascending sections of the loop have different functions. For example the descending section of the loop is permeable to water and not to sodium, etc 1. Proximal tubule: -reabsorption of Na -some secretion occurs *Na comes in through channels and transporters *Na out by the pump (Na out/ K in) 2. Loop of Henle -creates a high concentration of Na in the medulla (important for water reabsorption) a) descending limb -water permeable -no Na reabsorption *moves water out of the tubule by osmosis b) ascending limb -water impermeable -Na transported out of the tubule -removes Na with the Na/ K pump (Na out/ K in) -Na moves in through the channels Countercurrent: -occurs in Loop of Henle -blood flows in opposite directions in each arm of the loop -helps maintain the high concentration of Na in the medulla *Na moves into the descending limb because of the high concentration in the interstitium *Na moves back out of the ascending limb into the interstitium *blood flow in the medulla follows a loop *Na is kept in the medulla through the counter current exchange
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3. Distal tubule -fine tuning of Na, K, & protons (balance) -pump (Na out/ K in) 4. Collecting duct -control of Na & water reabsorption or excretion (balance) - Na moves into the cell -ADH present= water permeable -ADH not present= water impermeable *most of Na is absorbed by the time it gets to distal tubule and collecting duct *Na reabsorption is driven by the Na/ K pump= makes Na concentration in cell low *Na in lumen (outside cell)= high *Na in cell= low *each part of the nephron has a different Na channel/ transporter that allows Na to enter the cell - almost all fine tuning of Na occurs in the distal tubules and mostly in the collecting duct. - The proximal tubules are insensitive to hormonal regulation except by increasing GFR. (g. filtration) - fine tuning of Na reabsorption takes place in the distal tubules and collecting duct (cordical collecting duct). - ability of the collecting duct to change its reabsorption of water *Remember the later is connected to ADH levels. Understand the function of aldosterone and rennin’s (RAAS) role in regulating aldosterone levels.
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phys test 4 review - Understand Blood and filtrate flow...

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