Term
| what are the functions of kidneys |
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Definition
| controlling the following: water balance, blood volume, blood pressure, ion concentration, osmolarity (300mOsm), excretion of metabolic nitrogenous wastes, acid/base balance, EPO production, activation of vitamin D |
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Term
| what is EPO and what does it do |
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Definition
| erythropoietin; increases RBC production |
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Term
| what is the anatomy of the kidney |
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Definition
outer layer=cortex
inner layer= medulla
medulla divided into renal pyramids
renal pelvis to collect urine in kidney
ureters to bring urine to bladder |
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Term
| what is the function of the bladder |
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Definition
| to store urine until micturition |
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Term
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Definition
| convey urine form bladder to outside of the body (semen as well for men); longer for men (20cm) than women (3-4cm) |
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|
Term
|
Definition
| the functional unit of kidneys |
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Term
| what are the characteristics of nephrons |
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Definition
| 1 million/kidney; majority are cortical; they have a vascular component; Bowman's capsule |
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Term
| what is the vascular component of a nephron |
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Definition
| arterial branching with an emerging afferent arteriole that supplies the nephron which then branches into a tuft of capillaries known as the glomerulus which then merges into the efferent arteriold which then divides to form peritubular capillaries, which then rejoin into venules, which merge into a renal vein |
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Term
| what is the main characteristic of the peritubular capillaries |
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Definition
| they are interwined around the tubule |
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Term
| what is the tubular component |
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Definition
| a continuous hollow tube composed of special and epithelial cells |
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Term
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Definition
| the proximal end of the tubule and it collects the fluid, filtrate that is filtered from the glomerulus |
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Term
| what are the characteristics of Bowman's Capsule |
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Definition
| double-walled invagination that cups around the glomerulus; within the cortex |
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Term
| how does Bowman's Capsule work |
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Definition
| filtrate flows from bowman's capsule into the proximal (convoluted) tubule (PCT) before it enters the Loop of Henle, filtrate flows down descending limg of the loop before returning through ascending limb into the cortex passing through the tubule portion of the juxtaglomerular apparatus and then into the distal (convoluted) tubule (DCT) in the cortex |
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Term
| how many nephrons does one collecting duct drain |
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Definition
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Term
| what percentage of nephrons are cortical |
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Definition
|
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Term
| where are the cortical glomeruli |
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Definition
| in the outer cortex with the L of H dipping slightly into the medulla |
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Term
| where are the juxtamedullary nephrons glomeruli |
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Definition
| in the cortex next to the medulla with the long L of H dipping deep into the medulla |
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Term
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Definition
| specialized peritubular capillaries of the juxtamedullary nephrons |
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Term
| what are the three main renal processes |
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Definition
| glomerular filtration; tubular reabsorption; tubular secretion |
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Term
| what happens in glomerular filtration |
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Definition
| formation of filtrate that enters BC from the glomerular capillaries (180L/day) |
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|
Term
| what happens in tubular reabsorption |
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Definition
| selective movement of substances from the tubule back into the blood in the peritubular capillaries |
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Term
| what is tubular secretion |
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Definition
| selective movement of substances from blood in peritubular capillaries into the tubule |
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|
Term
| what is glomerular filtration |
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Definition
| the production of filtrate that enters bowman's capsule |
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Term
| what are the parts of the glomerular membrane |
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Definition
| glomerular capillary wall; basement membrane; inner wall of bowman's capsule (modified epithelial cells) |
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Term
| what are the characteristics of the glomerular capillary wall |
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Definition
| 1 layer of endothelial cells; many large pores; 100x more permeable to H2) and other solutes than systemic capillaries |
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Term
| what are the properties of the basement membrane |
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Definition
| secreted cellular material; composed of collagen and glycoproteins (neg charge); repels neg charge of plasma proteins (prevents small proteins from leaving the capillary) |
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Term
| what are the characteristics of the inner wall of bowman's capsule |
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Definition
| podocytes epithelial cells with several foot processes interdigitate with processes from adjacent cells that form filtration slits |
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Term
| what are the glomerular filtration forces |
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Definition
| glomerular capillaries are more permeable and filtration is favored along the entire length of the capillary; hydrostatic glomerular capillary pressure; plasma colloid osmotic pressure; hydrostatic pressure of filtrate in bowmans capsule |
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Term
| which way are the glomerular filtration forces pushing |
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Definition
| hydrostatic glomerular capillary pressure is 55mmHg outward; plasma colloid osmotic pressure is 30mmHg inward; hydrostatic pressure of filtrate in BC is 15mmHg inward |
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|
Term
| what is the net filtration pressure |
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Definition
| ~10mmHg favoring filtration |
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|
Term
| what is glomerular filtration rate (GFR) |
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Definition
| the volume of filtrate formed/unit time (~125ml/min) |
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|
Term
|
Definition
GFR=Kf*NFP
Net filtration pressure* filtration constant |
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|
Term
| What changes and doesn't change in NFP |
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Definition
| capillary pressure can be regulated while BC hydrostatic pressure and colloid osmotic pressure are not regulated |
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|
Term
| what affects the controlled adjuctinents in GFR |
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Definition
| controlled changes in glomerular BP |
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|
Term
| what keeps GFR constant despite momentary changes in MAP |
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Definition
| autoregulatory mechanisms within the kidney |
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|
Term
| What do the extrinsic sympathetic controls of GFR do |
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Definition
| they are necessary for long-term regulation of BP; regulation of BV; if long-term increase in BP results in in increase in GFR, decrease in BF, and decrease in BP |
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|
Term
| what are the two types of autoregulatory mechanisms |
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Definition
| myogenic mechanism and tubuloglomerular feedback |
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Term
| What is the myogenic mechanism |
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Definition
| if there is an increase in MAP, there is an increase in stretch in the afferent artery which causes vasoconstriction in the afferent artery and a decrease in blood flow into the glomerulus and a decrease in BP in the glomerulus |
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|
Term
| what does autoregulation do |
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Definition
| holds GFR constant despite changes in MAP |
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Term
| what does the myogenic mechanism do |
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Definition
| it is how arteries and arterioles react to an increase or decrease of blood pressure to keep the blood flow within the blood vessel constant. |
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Term
| how does the myogenic mechanism work |
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Definition
| increase in BP results in increase in stretch of afferent arteriole resulting in vasoconstriction which reduces BF into glomerulus which reduces BP in glomerulus until it is back to normal; opposite if BP decreases |
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|
Term
| where does tubuloglomerular feedback occur |
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Definition
| the juxtaglomerular aparatus (JGA) |
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|
Term
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Definition
| specialized cells of distal tubules at JGA |
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Term
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Definition
| specialized cell of afferent arteriole wall at JGA |
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Term
| what happens in tubuloglomerular feedback if there is an increase in MAP and an increase in GFR |
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Definition
| detected as increase in filtrate flow by the macula densa--> macula densa release ATP and adenosine causing vasoconstriction in afferent arterioles |
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Term
| what happens in tubuloglomerular feedback if there is decrease in BF into glomerulus |
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Definition
| there is a decrease in BP in the glomerulus and a decreased GFR |
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Term
| what does long-term regulation of blood pressure result from |
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Definition
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|
Term
| what can activation of the sympathetic nervous system do |
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Definition
| override the autoregulatory mechanism |
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|
Term
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Definition
| it can alter the volume of water in urine |
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Term
| what results from a decrease in MAP due to hemorrhage |
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Definition
| the sympathetic nervous system is activated causing systemic vasoconstriction which leads to afferent arteriole constricting which causes a decrease in GFR leading to decrease in urine volume and conservation of water to preserve blood volume |
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Term
| what happens if there is an increased BP (excess fluid intake) |
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Definition
| vasodilation (reduced sympathetic tone) leading to afferent arteriole vasodilating which causes an increase in glomerular filtration pressure which causes and increased GFR and more urine volume to get rid of fluid volume which leads to a decreased BP |
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|
Term
| what happens in tubular reabsorption |
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Definition
| essential materials are reabsorbed from filtrate into peritubular capillaries |
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|
Term
| what percentage of water is reabsorbed by capillaries |
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Definition
|
|
Term
| what percentage of sugar is reabsorbed by capillaries |
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Definition
|
|
Term
| what percentage of salt is reabsorbed by capillaries |
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Definition
|
|
Term
| what happens in transepithelial reabsorption |
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Definition
| substances must cross the luminal membrane then out through the basolateral membrane |
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|
Term
| where does Na reabsorption occur |
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Definition
| along the entire length of the tubule except the descending limb of L of H |
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|
Term
| in what parts is the Na reabsorbed |
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Definition
| 67% is reabsorbed in the proximal CT; 25% in the ascending L of H; 8% is variably reabsorbed in DCT and CD |
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|
Term
| What happens if the Na load of the body is too high |
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Definition
| the ECF will have higher osmotic activity; more water will be held leading to increased ECF volume which leads to increased BV and BP which leads to increased stretch in the wall of the heart |
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Term
| what happens when the wall of the heart has an increased stretch |
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Definition
| atra secrete atrial natriuretic peptide (ANP); ventricles secrete brain natriuretic peptide (BNP) |
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Term
| what does brain natriuretic peptide (BNP) do |
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Definition
| it inhibits sodium reabsorption at DCT and CD which decreases Na load leading to a decrease in ECF vol and then a decrease in BV and BP |
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Term
| What does a decreased Na load cause |
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Definition
| granular cells release renin (enzymatic hormone); angioteninogen goes to angiotensin I and then to angiotensin II |
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|
Term
| how does angiotensin I go to angiotensin II |
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Definition
| angiotensin converting enzyme |
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|
Term
| what does angiotensin II cause |
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Definition
| it is a vasoconstrictor which causes thirst and stimulates release of vasopressin and helps form aldosterone |
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|
Term
|
Definition
| a steroid hormone in the adrenal cortex that targets the distal tubule cells of the kidney to increase reabsorption of Na |
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|
Term
| what nutrients are reabsorbed and how |
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Definition
| glucose and amino acids mostly through secondary active transport iwth Na being the driving ion in most cases |
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|
Term
| What does nutrient reabsorption rely on |
|
Definition
| on transporters embedded in the membrane with there being a finite number |
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|
Term
| what is the concentration of blood plasma and what is it regulated by |
|
Definition
| 100mg/100ml regulated by insulin/glucagen system |
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|
Term
| what is the tubular maximum |
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Definition
| the maximum Tm which is the max amount of substance that can be reabsorbed by the tubule |
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|
Term
| what is the approximate max amount that can be reabsorbed by the tubule |
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Definition
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|
Term
| how can the amount being absorbed per minute be calculated |
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Definition
| concentration*rate of abosrption |
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|
Term
| where is water reabsorbed |
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Definition
| 80% is reabsorbed obligatorily in PCT and L of H; 20% is variable reabsoprtion in CD |
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|
Term
|
Definition
| water channels that facilitate osmosis |
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|
Term
| what is the state of aquaporins in PCT |
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Definition
|
|
Term
| what is the state of aquaporins in CD |
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Definition
| it is regulated by ADH and vasopressin |
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|
Term
| what is tubular secretion |
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Definition
| the selective movement of substances from peritubular capillaries into lumen of tubule |
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|
Term
| what are K, H, organic anions, and cations in regards to tubular secretion |
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Definition
| metabolites of foreign substances |
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|
Term
| what is the importance of H+ secretion |
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Definition
| pH balance; if drop in pH, increase in [H] secretion; if increase in pH, decrease in [H] secretion |
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|
Term
| what happens to K+ in tubular secretion |
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Definition
| most filtered K is actively reabsorbed in proximal tube and it is constant and unregulated; actively secreted in the DCT and CD which is hormonally regulated and depons on needs of the body and aldosterone |
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|
Term
| what does aldosterone do in tubular secretion |
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Definition
| released in response to increased [K] in the plasma which leads to increased K secreted which leads to a decrease in [K] in the plasma |
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|
Term
| what does urine concentration depend on |
|
Definition
| hydration state of kidneys (300mOsM is average) |
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|
Term
| how do kidneys regulate urine concentration |
|
Definition
| interstitial fluid osmolarity gradient; L of H of justomedullary nephrons producing/maintaining the gradient; vasopressin controlling variation in urine concentration |
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|
Term
| what is the osmolarity of the interstitial fluid osmolarity gradient |
|
Definition
| 300-1200 mOsM in the cortex |
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|
Term
| what are the limbs of the L of H of the justomedullary nephrons permeable to |
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Definition
| In the descending, permeable to H20 and impermeable to Na/Cl; in the ascending limb, actively reabsorbs Na and impermeable to H2O |
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|
Term
| how does vasopressin control variation in urine concentration |
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Definition
| distal tubule and CD are impermeable to H2O except in the presence of vasopressin; when osmolarity is increased, osmoreceptor cells in hypothalamus trigger release of vasopressing from posterior pituitary |
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|
Term
| How does vasopressin work |
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Definition
| it circulates, targets distal cells of tubule and CD which leads to more open aquaporins |
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|
Term
| what happens when there is increased osmolarity |
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Definition
| vasopressin is released; increased amount of water is reabsorbed in the DCT and CD; lower volume of concentrated urine |
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