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36 Cards in this Set
- Front
- Back
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Define excretion.
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"The removal from the body of the waste products of metabolic pathways."
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Define osmoregulation.
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"The control of the water balance of the blood, tissue, or cytoplasm of a living organism."
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Label "A" on the excretion flashcard diagram
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renal artery
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Label "B" on the excretion flashcard diagram
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renal vein
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Label "C" on the excretion flashcard diagram
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ureter
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Label "D" on the excretion flashcard diagram
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(pyramids of) medulla
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Label "E" on the excretion flashcard diagram
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cortex
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Label "F" on the excretion flashcard diagram
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outer membrane of kidney
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Label "G" on the excretion flashcard diagram
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pelvis of kidney
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Label "I" on the excretion flashcard diagram.
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proximal convoluted tubule
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Label "II" on the excretion flashcard diagram.
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descending loop of Henle
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Label "III" on the excretion flashcard diagram.
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ascending loop of Henle
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Label "IV" on the excretion flashcard diagram.
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distal convoluted tubule
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Label "V" on the excretion flashcard diagram.
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collecting duct
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Label "VI" on the excretion flashcard diagram.
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renal artery (or arterioles)
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Label "VII" on the excretion flashcard diagram.
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glomerulus
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Label "VIII" on the excretion flashcard diagram.
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path of urine toward renal pelvis and ureter
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Label "IX" on the excretion flashcard diagram.
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renal vein (or venules)
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Label "X" on the excretion flashcard diagram.
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Bowman's capsule
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Label "XI" on the excretion flashcard diagram.
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capillaries
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In the diagram of the nephron and associated blood vessels on the excretion sheet, what pathway will glucose (or any small molecule you want to keep in the body) take?
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VI, VII, X, I, XI (enters blood from proximal convoluted tubule for glucose, amino acids plus some salt and water…can be later for additional water and salt), IX
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In the diagram of the nephron and associated blood vessels on the excretion sheet, what pathway will urea take?
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VI, VII, X, I, II, II, IV, V, VIII
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In the diagram of the nephron and associated blood vessels on the excretion sheet, what pathway will blood cells or plasma proteins take?
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VI, VII, XI, IX
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Where does ultrafilatration take place?
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glomerulus
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What is the liquid called that is found within the nephron?
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filtrate
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Explain the process of ultrafiltration (in excretion)
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There is high pressure in the afferent arterioles that lead into the glomerulus and the efferent arterioles that lead out of the glomerulus. This results in a high pressure in the glomerulus that leads to ultrafiltration, which happens at the glomerulus/Bowman's capsule. Ultrafiltration happens through fenestrated capillaries that moke up the glomerulus. The fenestrations are opening between the cells of the capillary. Under pressure, these openings allow small molecules (like glucose, amino acids, salts, urea) to travel out of the blood plasma and into the Bownan's capsule, becoming the filtrate. The basement membrane which surrounds the glomerular capillaries prevents anything large (blood cells, plasma proteins) from passing through.
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Explain the process of reabsorption (in excretion)
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Glucose, water and some salt is selectively reabsorbed in the proximal convoluted tubule. The cells of the proximal convoluted tubule have microvilli, which greatly increases the surface area of the cells and therefore increase the efficiency of reabsorption. The cell membranes of these cells contain protein pumps for active transport of glucose, amino acids, and some salt from the filtrate into the cells of the proximal convoluted tubule. Salt can move by facilitated diffusion as well as active transprt. The filtrate in the tubules is hypotonic compared to the surroundings (which are hypertonic), and so water moves out of the tubules by osmosis...about 80% of the water is reabsorbed here. The glucose, amino acids, some water and some salt enter the capilaries. There are lots of mitochondria in the cells of the proximal convoluted tubule to provide energy for all of this active transport. Also, pinocytotic vesicles can be seen in the cells. Although the standards primarily talk about reabsorption in
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What substances are selectively reabsorbed during excretion?
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glucose, amino acids, salt, water
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What substance is NOT selectively reabsorbed during excretion?
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urea
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How does the blood in the renal artery compare to blood in the renal vein?
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The renal artery has more of the following than the renal vein: oxygen, urea, toxins. The renal vein has more of the following than the renal artery: carbon dioxide (the kidney, like all cells in your body, has done cell respiration). The total amount of salt (NaCl) and water is higher in the renal artery than the renal vein.
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How does the blood in the glomerulus compare to the filtrate in the Bowman's capsule?
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The filtrate does NOT have plasma proteins and blood cells that remain in the capillaries during ultrafiltration. Small molecules--water, amino acids, glucose, salt, urea, toxins--are found at equal concentrations as in the blood due to diffusion through the basement membrane surrounding the glomerulus.
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How does the composition of glomerular filtrate compare to the composition of urine?
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Urine has no glucose and amino acids and fewer water and salt molecules due to the selective reabsorption process. Urea is found in both because it is NOT selectively reabsorbed. The concentration of salt and urea is higher than in the glomerular filtrate because so much of the water was reabsorbed as it passed through the nephron. No proteins or blood cells should be found in either of these places.
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What molecule is found in the urine of a diabetic that is NOT found in the urine of a non-diabetic? Why?
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Glucose. In diabetes, the body is unable to appropriately reduce blood sugar following a meal. The blood glucose is therefore higher than normal. When all of this excess glucose comes into the nephron, the protein pumps that actively transport glucose in the proximal convoluted tubule are unable to work fast enough to move such an unusually large amount of glucose from the filtrate. Therefore, some glucose remains in the nephron, travelling through the loop of Henle, the distal convoluted tubule, and the collecting duct and becoming part of the urine.
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If protein or blood cells are found in urine, what has been damaged?
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the basement membrane (which surrounds the glomerulus/fenestrated cappilaries and is in charge of making sure large things don't become part of the filtrate)
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What is the role of the loop of Henle, medulla, collecting duct, and ADH in maintaining the water balance of the blood?
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The loop of Henle makes the medulla of the kidney hypertonic by raising the sodium ion concentration. This allows the production of concentrated (hypertonic) urine. The medula is made hypertonic due to the addition of these sodium ions, causing water to leave the loop of Henle by osmosis (the loop of Henle is permeable to water). The collecting duct has variable permeability to water. When the water content of the blood is too low, the pituitary gland in the brain secretes ADH. ADH makes the cells of the collecting ducts make membrane channels (called aquaporins) which make the collecting duct more permeable to water, allowing more water to leave the collecting duct and result in a more concentrated urine. If the water content of the blood is too high, ADH will no longer be made, the aquaporins will break down, and the collecting duct becomes less permeable to water. (More detail in H.1.5)
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Explain the control of ADH (vasopressin) secretion (H.1.5) and the effects of ADH on the body.
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This is an example of negative feedback ADH is produced in the hypothalamus.
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