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60 Cards in this Set
- Front
- Back
nitrogenous wastes |
urea
uric acid creatinine |
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kidney functions
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excrete nitrogenous wastes regulate blood volume regulate blood pressure regulate blood chemical stabilize pH convert vitamin D into active form |
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regulate the rate of filtration and blood pressure
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macula densa granular cells |
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macula densa |
in the DCT, contain osmoreceptors that monitor solute concentration and flow rate of filtrate |
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granular cells |
smooth muscle cells in the afferent arteriole, act as mechanoreceptors to monitor BP, synthesize and secrete renin |
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renin |
hormone that |
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nephron renal processes |
glomerular filtration tubular reabsorption tubular secretion excretion |
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glomerular filtration |
plasma filtered from the glomerulus into Bowman's capsule; solutes and hydrostatic pressure forces fluid through the filtration membrane; blood cells and plasma proteins too large to enter filtrate |
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glomerular capillary BP (55 mmHg) |
result of BP pushing on the inside of the capillary wall |
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plasma-colloid osmotic pressure (30 mmHg) |
due to retention of plasma proteins in the blood of glomerulus; concentration of water is higher in Bowman's capsule because proteins are absent there and water tends to return to glomerulus by osmosis |
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Bowman's capsule hydrostatic pressure (15 mmHg) |
tend to move fluid from Bowman's capsule into the glomerulus |
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glomerular net filtration pressure |
glomerular BP - (plasma-colloid osmotic pressure + Bowman's capsule hydrostatic pressure) |
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GFR efficiency |
higher pressure bc afferent larger than efferent arteriole number of nephrons ↑ surface area permeability of capillary pores |
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GFR too high |
needed substances cannot be reabsorbed quickly enough and are lost in the urine |
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GFR too low |
everything is reabsorbed, including wastes that are normally disposed of |
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GFR mechanisms of control |
renal autoregulation (intrinsic control)
sympathetic NS (extrinsic control) hormones (renin-angiotensin-aldosterone system) |
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renal autoregulation (intrinsic control; short term) |
regulates the GFR by factors within the kidneys and normally prevents inappropriate changes in the GFR by myogenic mechanism and tubuloglomerular feedback mechanism |
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myogenic mechanism |
type of renal autoregulation that is controlled by arteriole smooth muscle cells and responds to changes in pressure in the renal blood vessels by constricting the afferent arteriole if pressure is too high, resulting in lower GFR |
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tubuloglomerular feedback mechanism |
type of renal autoregulation that is controlled by macula densa cells in the JGA and senses changes in flow rate in the nephron's tubular component so that the release of vasoactive chemicals would be stimulated if flow rate is too high, resulting in vasoconstriction of afferent arterioles |
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sympathetic NS (extrinsic control; long term) |
overrides autoregulatory mechanism when blood volume drops stimulates renin-angiotensin-aldosterone system |
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renin-angiotensin-aldosterone system |
triggers ↓ stretch of granular cells stimulates granular cells by activating macula densa cells directs stimulation of granular cells via β₁-adrenergic receptors promotes ↑ systemic BP and volume |
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angiotensin II |
causes systemic arteriole vasoconstriction stimulates adrenal cortex to release aldosterone |
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granular cells |
releases renin that acts on angiotensinogen to make angiotensin I, which converts to angiotensin II |
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tubular reabsorption |
selective transfer of substances needed by the body from the filtrate back into the peritubular capillaries |
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transepithelial transport |
by this method a reabsorbed substance must cross the tubule wall, enter the interstitial fluid, and pass through the wall of the peritubular capillaries, entering the blood |
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luminal membrane and a basolateral membrane |
membranes of the epithelial cells of the nephron tubule |
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Na⁺ diffuses through tubule cells at luminal membrane then actively transported by Na/K pump at basolateral membrane |
how sodium reabsorption occur at the tubules |
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proximal tubule |
where 67% of Na⁺ reabsorption occur at a constant rate |
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loop of Henle |
reabsorption of Na⁺ here produces varying concentrations and volumes of urine |
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distal tubule |
reabsorption of Na⁺ here is variable depending on needs of body and level of aldosterone |
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aldosterone |
this hormone increases Na⁺ absorption in the DCT and collecting ducts |
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insert more Na⁺ channels in the luminal membrane insert more Na/K pumps in basolateral membrane |
what aldosterone can do to promote Na⁺ absorption |
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atrial natriuretic peptide (ANP) |
this hormone inhibits Na⁺ reabsorption which decreases blood volume and lowers BP by acting directly on collecting ducts, inhibit renin pathway, and dilate afferent arteriole to trigger ↑ GFR which ↓ water and sodium reabsorption |
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reabsorption by proximal convoluted tubule cells |
cells that drives reabsorption of the following: water by osmosis, aided by aquoporins anions follow by diffusion down electrochemical gradient glucose and amino acids by secondary active transport |
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proximal tubule and loop of Henle |
80% of water reabsorption is obligatory in these areas and occurs by osmosis without control |
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distal tubule and collecting duct |
20% of water reabsorption is facultative in these areas and based on the secretion of ADH, depending on body's needs |
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ADH |
hormone that works on tubule cells through a cyclic AMP mechanism (secondary active transport) to reabsorb 99% of the water in the filtrate |
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concentrated |
what ADH causes urine to become |
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glucose and amino acids |
minerals that are reabsorbed by secondary active transport and cotransported with sodium on the luminal membrane |
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transport maximum |
this reflects the number of carriers in the renal tubules available and exists for nearly every substance that is actively reabsorbed; when the carriers are saturated, excess of that substance is excreted |
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urea, creatinine, uric acid, excess K⁺, other nitrogenous waste |
substances that lack carriers, are not lipid soluble, and are too large to pass through membrane pores |
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tubular secretion |
selective process by which substances from the peritubular capillaries enter the lumen of the nephron tubule in order to speed up the elimination of substances from the blood (instead of waiting for blood to get back to glomerulus) |
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distal tubule |
where excess potassium secretion occurs |
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aldosterone |
hormone that stimulates tubular cells to secrete potassium if plasma potassium levels are too high |
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1. chemical buffers in blood act within seconds 2. respiratory center in brain stem acts within 1-3 min 3. renal mechanisms need hours to days to ∆ pH |
regulation of acid-base balance (concentration of H⁺) |
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renal mechanisms of acid-base balance |
reabsorb/generate new bicarbonate ions if acidosis (lose H⁺) excrete bicarbonate ions if alkalosis (gain H⁺) |
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phosphate buffer system |
when excreted H⁺ binds to buffers in the urine |
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response to acidosis |
type A cells generate bicarbonate ions and add them to blood an equal amount of H⁺ are added to the urine H⁺ binds with buffers in the filtrate (monohydrogen phosphate) |
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response to alkalosis |
type B cells exhibit bicarbonate ion secretion type B cells reclaim H⁺ and acidify the blood |
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vertical osmotic gradient |
the large variation in reabsorption in the interstitial fluid of the renal medulla (300-1200 mosm/liter) |
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countercurrent |
the movement of opposite directions of filtrate through the ascending and descending limbs of the loop of Henle, also applies to the flow of blood through the vasa recta |
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countercurrent multiplier |
refers to the ability to increase the osmolarity of the interstitial fluid |
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descending loop of Henle |
is relatively impermeable to solutes is permeable to water |
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ascending loop of Henle |
is permeable to solutes is impermeable to water, doesn't follow Na⁺ by osmosis actively transports NaCl out of tubular lumen |
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interstitial fluid |
ascending loop of Henle produces this that becomes hypertonic to the descending limb in order to attract water by osmossis for reabsorption |
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countercurrent exchanger |
the hairpin structure of the vasa recta that allows the blood of the vasa recta to equilibrate with the interstitial fluid |
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high glucose levels alcohol caffeine/drugs |
osmotic diuretics |
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high glucose level diuretic |
osmotic diuretic that carries water out with the glucose |
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alcohol diuretic |
osmotic diuretic that inhibits the release of ADH |
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caffeine and most diuretic drugs |
osmotic diuretics that inhibit sodium ion reabsorption |