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21 Cards in this Set
- Front
- Back
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PCT is what?
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Proximal convoluted tubule
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in the PCT, what is:
-Absorbed -Secreted |
Absorbed:
100% Glucose/Amino acids 70% Water, Na, and K+ Secreted: 100% PAH |
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What happens to filtrate osmolarity at the PCT?
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It does not change.
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What are the 4 steps of reabsorption in the PCT?
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1. Na/K pump makes [Na] low inside PCT cells; Na is reabsorbed.
2. Na reabsorption makes Glucose/AA move into PCT cell up conc. gradient 3. They move into capillary via facilitated diffusion. 4. Water follows them and gets reabs by SIMPLE diffusion (to maintain osmolarity). 3. 3. |
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what type of transport is
-Na reabsorption -Glu/AA reabsorption from lumen to PCT cell |
-Sodium is primary active transport
-Glu/AA is secondary - uses the energy from Sodium's transport. |
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what is the brush border membrane, and where is it?
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the membrane on the inside of the PCT lumen, with increased surface area for enhanced reabsorption.
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What are the 4 (really 5) steps of secretion in the PCT?
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1. Na/K pump makes low [Na] inside the PCT cell
2a. Na moves from blood to cell. 2b. a-ketoglutarate moves into cell using energy from #2 3. a-ketoglu moves BACK down its conc. gradient into blood, 4. Allows PAH to move UP its conc. gradient. into PCT cell. |
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Type of transport when using a-ketoglu's energy to move PAH from blood to PCT cells:
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Tertiary active transport (because a-ketoglu used Na's energy in the first place).
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What occurs in the
-Descending loop of Henle -Ascending loop of Henle What general part of the kidney is this? |
Desc: WATER IS REABSORBED.
Asc: Na and Cl are reabsorbed - no water! -In the renal medulla. |
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What are the 3 step of reabsorbption in the Asc loop?
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1. Na/K pump makes [Na] low inside PCT cells.
2. Na moves in from lumen, Cl also but UP its conc. gradient. 3. Water STAYS in the lumen; the filtrate becomes hypotonic to the outside. |
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Why is H2O not reabsorbed in the ascending loop?
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b/c membrane is impermeable, due to TIGHT JUNCTIONS between the cells of the membrane.
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What happens to the ISF during reabsorpn of NaCl in asc loop?
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Becomes concentrated - if it's a juxtamed. nephron, this allows for urine concentration.
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What occurs in the distal convuluted tubule (DCT)?
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-same processes as in the ascending loop - reabsorption of NaCl, but not water.
-Tubule fluid becomes 50 mOsm - more hypotonic. |
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when NaCl are reabsorbed, what types of conc. gradients are being fought?
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Na isn't - moves DOWN conc. grd.
Cl is - moves UP its conc. grad. |
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what is the distal nephron composed of?
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-Distal Convoluted Tubule (DCT)
-Collecting Duct |
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What occurs in the collecting duct?
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Fine tuning of the filtrate by HORMONE ACTION.
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what hormones are responsible for finetuning the filtrate in the collecting duct?
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-Aldosterone
-ADH (antidiarrh. hormone) |
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How does Aldosterone work in the collecting duct?
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Steroid action produces more Na/K pumps; causes increased -Sodium reabsorptn
-Potassium secretion. |
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How does ADH work in the collecting duct?
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Makes membrane H2O-permeable, thus increased H2O reabsorptn.
a. Low ADH makes dilute urine. b. High ADH = it concentrated. |
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how does ADH affect urine volume?
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High ADH = small amounts of concentrated urine.
Low ADH = large amounts of dilute urine. |
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What does Alcohol do to ADH?
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well you pee a lot so you have large amts of dilute urine so ADH is low = alcohol inhibits its formation.
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