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11 Cards in this Set
- Front
- Back
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Describe the role of ADH in osmoregulation. (4)
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a. osmoregulation is control of water balance in organisms/blood/tissues/cytoplasm;
b. ADH regulates water levels/solute concentration of the blood; c. produced/released when water in blood is too low; d. it increases the permeability of the collecting ducts / increase in the reabsorption of water; e. leads to more aquaporins (in collecting duct cell membranes); f. lower volume/less urine is produced/urine more concentrated; |
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Define the term excretion.
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removal of waste products of cell reactions/metabolic activities/pathways
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Explain the process of ultrafiltration. (2)
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blood (in the glomerulus) under high pressure caused by difference in diameter of (afferent and efferent) arterioles;
fluid plasma and small molecules forced into kidney tubule/Bowman’s capsule/through fenestrations/basal membrane; which prevent larger molecules/blood cells from passing through; |
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Add photo may 2011TZ2
Compare the composition of the fluids found in the regions labelled I and II by giving one difference and one similarity. |
difference: fluid at II has less urea/glucose/oxygen/salts/ions/water;
similarity: fluid at II has same (amount of) proteins/blood cells as fluid at I; |
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Explain why diabetes could be detected through the analysis of urine. (8)
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urine of diabetics contains glucose;
whereas urine of non-diabetics contains no glucose; glomerular filtrate contains glucose / glucose filtered out; glucose (normally) reabsorbed from filtrate/into blood; through wall of / in the proximal convoluted tubules; blood glucose concentration higher than normal in diabetics; reabsorption not completed / pumps cannot reabsorb all glucose in diabetics; glucose in urine can be detected using test strips; type I diabetes is lack of insulin secretion / lack of β cells; type II diabetes is body cells not responding to insulin / not absorbing glucose; |
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Suggest why oxidation of membrane lipids may lead to increased protein loss in the urine. (3)
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proteins retained (in blood) during ultrafiltration (in a healthy person);
proteins are large (molecules); proteins lost/leak from blood/into filtrate/into Bowman’s/renal capsule; large enough pores/holes/spaces formed for proteins to pass through; glomerulus/capillary/walls/podocytes/Bowman’s/ renal capsule damaged; proteins are too big to be reabsorbed later/in proximal convoluted tubule; |
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Explain the main role of each of the following in maintaining the water balance of
the body. (i) Loop of Henlé (ii) collecting duct (III) ADH |
(i) Loop of Henlé:
increase solute concentration of the medulla/in cells and tissue fluid in medulla / set up osmotic gradient in the medulla; reclamation of salts and water; counter current multiplier; (ii) collecting duct: (osmoregluation of water content of blood by) absorbing water (or not) from the urine (III) increases/promotes the re-absorption of water in the collecting duct / makes collecting duct permeable to water |
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Explain how water balance is maintained in the blood. (8)
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ADH released (by the pituitary) when blood solute high;
ADH makes cells of the collecting duct more permeable; more water is reabsorbed / concentrated urine produced; solute gradient within the medulla draws water from filtrate; leads to water reabsorption in the descending loop of Henle; ascending limb is impermeable to water (at upper reaches); (lower) ascending limb permeable to sodium ions/ Na+ pumped out of (upper) ascending limb; which contributes to the establishment of a solute gradient; more Na+ at base of loop / deeper in medulla; some water re-absorbed in proximal convoluted tubule; capillaries associated with nephron absorb reclaimed water; once water level returns to normal/low blood solute, release of ADH stops; less water is reabsorbed / dilute urine produced; |
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Explain the processes occurring in the kidney that contribute to osmoregulation. (8)
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a. osmoregulation is maintenance of water balance of blood/tissues;
b. loop of Henle creates hypertonic conditions in the medulla; c. water reabsorbed as filtrate passes through collecting duct; d. hypothalamus monitors/controls water balance/content of blood; e. controls secretion of ADH by (posterior) pituitary gland; f. ADH is released when blood too concentrated/too little water/hypertonic; g. ADH makes the collecting duct more permeable to water; h. due to more aquaporins; i. more water reabsorbed (in response to ADH); j. less water in urine/urine more concentrated/urine hypertonic; k. no/less ADH when blood too dilute/too much water/hypotonic; l. collecting duct less permeable/less water reabsorption/more water in urine; |
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Explain how the collecting ducts can alter the volume of urine produced by the kidney. (5)
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ADH is secreted when the solute concentration of the blood is too
high/OWTTE/converse; ADH makes the collecting duct more permeable to water / when not secreted the collecting duct is less permeable to water; (causes) more aquaporins in the (membranes of cells in the) collecting duct; collecting duct passes through medulla; increasing salt concentration of medulla / hypertonic medulla; leading to osmosis / more water is reabsorbed (from the collecting duct); so volume of urine is less / urine more concentrated; (without ADH) higher flow rates so less time for water reabsorbtion; (without ADH) dilute / large volume of urine is produced; |
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Explain the processes occurring in the kidney that cause differences in the concentrations of these solutes between blood plasma, glomerular
filtrate and urine. (8) |
(filtrate formed by) ultrafiltration;
glucose / amino acids / soluble components enter Bowman’s capsule; proteins in blood plasma but not in filtrate / proteins not filtered out (of blood); glucose not in urine (normally); (selective) reabsorption (of glucose); in the proximal convoluted tubule; by active transport / microvilli increase the surface area; little/no urea reabsorbed concentration increases / urea more concentrated in urine than in blood plasma; water reabsorbed from filtrate; by osmosis; in descending limb of nephron / in proximal convoluted tubule; salts actively transported into the medulla (from filtrate); creating concentration gradient/hypertonic medulla; collecting duct permeability altered depending on blood solute concentration; |
