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25 Cards in this Set
- Front
- Back
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What do the kidneys excrete?
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urea - from amino acid metabolism
creatinine - from muscle creatine uric acid - from nucleic acids hemoglobin - breakdown end products metabolites of hormones foreign chemicals - drugs, pesticides |
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How do the kidneys regulate blood pressure?
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Short term - via excretion of water and sodium to control blood volume
Long term - secrete vaso-active factors which cause vasodilation or constriction, and angiotension II |
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In what ways to the kidneys regulated water and electrolyte balance?
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control sodium, potassium, chloride and other ions; maintain homeostasis; intake balances excretion; important for neural function
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How do the kidneys regulate plasma osmolarity and pH?
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concentration of solutes and acids/bases
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how do kidneys control erythrocyte production?
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Secretion of erythropoietin (red blood cell production)
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Why is vitamin D3 important for the kidneys to produce?
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D3 is a key for calcium deposition in bones
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How do the kidneys assist with glucose synthesis?
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During fasting kidneys can produce glucose from amino acids via gluconegenesis process
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What is the blood system that surrounds the nephron in order from artery to vein?
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arcuate artery, interlobular artery, afferent artery, glomerulus, efferent artery, vasa recta (peritubular capillaries)
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What is the order of the duct system from the Bowman's capsule?
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Bowman's capsule, proximal tubule, descending limb of the loop of Henle, ascending limb, macula densa, distal tubule, cortical collecting tubule, collecting duct
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Difference between juxtamedullary nephron and cortical nephron?
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Juxtamedullary has a longer loop of Henle for more water re-uptake (more in medulla), cortical has a shorter loop of Henle and has more in the cortex
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What is involved in filtration?
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Glomerulus (hydrostatic and osmotic pressure) into bowman's capsule and 3 layers of epithelial cells
- Bowman's capsule is essentially impermeable to proteins |
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How is the glomerular membrane organized? from capillary lumen to bowman's space
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Capillary endotheial cells with fenestration spaces between cells, basement membrane, epithelial cell with slit pore spaces; basement membrane helps to limit the amount of plasma that can filter through
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Why do we need to control the rate of filtration?
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mean arterial pressure changes often and this can alter the glomerulus filtration rate but this would lead to changes in urine output
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How does intrinsic control affect filtration rate?
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afferent arterial constriction through myogenic regulation (smooth muscle), tubuloglomeruluar feedback (is in close proximity with the ducts of the glomerulus), and mesangial cell contraction (similar to myogenic)
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At what mean arterial pressure does extrinsic vs intrinsic control occur?
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lower than 80 is severe blood loss (extrinsic), between 100 - 180 is intrinsic, higher than 180 extrinsic
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What is secretion?
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same as reabsorption only in the opposite direction; movement of plasma into tubular fluid to create filtrate which eventually becomes urine; generally ions, waste products and foreign substances are secreted
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What is secreted and reabsorbed in the proximal tubule?
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everything is reabsorbed and H+ is secreted
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What is reabsorbed in the descending loop of Henle?
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water
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What is reabsorbed in the ascending loop of Henle?
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Reabsorbed: Na, Cl, K, Mg, Ca
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What is reabsorbed and secreted in the distal tubule?
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Reabsorbed: Na, Ca, Cl, water; secreted: K, H
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What is reabsorbed and secreted in the collecting duct?
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Reabsorbed: Na, K, Cl, Ca, HCO, H, urea, water; secreted: K and H
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What is the equation for excretion?
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excretion = filter + secrete - reabsorbed
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What is clearance and how does it affect solute?
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- the rate at which a solute is excreted
- the rate of the glomerulus is 125mL/min; if clearance is greater there is net secretion, and if clearance is lower the net movement is reabsorption |
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Kidneys and water balance: how much is reabosrbed and where?
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70% reabsorbed, done passively; other 30% is what kidneys control when they need to; regulation occurs in then distal tubule and collecting duct
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How is water reabsorbed?
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Medullary osmotic gradient - sodium levels increase down the loop of Henle which encourages water to leave the loop to enter the blood
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