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18 Cards in this Set

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App. 40-50% of the filtered urea is reabsorbed in the proximal tubule. TRUE/FALSE
TRUE. The DCT and the cortical collecting tubules are relatively impermeable to urea.
The conc. of urea in the renal medullary interstitial fluid is markedly increased because of reabsorption of urea from the collecting ducts, which contributes to the hyperosmotic renal medulla.
Normally, where is the most water reabsorbed?
In the proximal tubule(60-65%). Dehydration increases water permeability in the cortical and medullary collecting ducts.
A person with normal body fluid volumes weighs 60 kg and has an extracellular fluid volume of app 12.8 liters, a blood volume of 4.3 liters, and a PCT of 0.4: 57% of his body weight is water.What is the app. intracellular fluid volume?
21.4 liters
Intracellular fluid volume is calculated as the difference between total body fluid(0.57X60 kg=34.2, or app. 34.2 liters) and extracellular fluid volume(12.8 liters), which equals 21.4 liters.
Where is the primary site of Mg reabsorption?
It is in the loop of Henle, where app. 65% of the filtered load of Mg is reabsorbed. The PCT normally reabsorbs about 25% of filtered magnesium, and the distal and collecting tubules reabsorb less than 5%.
Autoregulation of the renal blood flow and glomerular filtration rate by tubuloglomerular feedbacxk requires what?
The TFM for renal autoregulation involves signaling from the macula densa to the juxtaglomerular cells. Increased arterial pressure raises NaCl delivery to the macula densa, which initiates vasoconstriction of renal afferent arterioles and decreased release of renin.
GFR is app. = to the clearance of creatinine. TRUE/FALSE
TRUE.
creatinine clearance =
urine creatinine conc X urine flow divided by plasma creatinine conc.
What is the result of severe diarrhea regarding acid status?
Severe diarrhea would result in loss of HCO3 in the stool, thereby causing metabolic acidosis that is given by low plasma HCO3 and low pH. Respiratory compensation would reduce PCO2.
Plasma chloride conc. would be elevated as well caused by HCO3 loss in the stool.
Primary excessive secretion of aldosterone causes metabolic alkalosis. TRUE/FALSE
TRUE. This is due to increased secretion of H+ ions by the intercalated cells of collecting tubules.
What causes proximal tubular acidosis?
This results from a defect of renal secretion of H+ ions, reabsorption of bicarbonate, or both. This leads to increased renal excretion of HCO3 and metabolic acidosis given by low plasma HCO3 conc, and low plasma pH.
A patient with diabetic ketoacidosis and emphysema would be expected to have metabolic acidosis(due to excess ketoacids in the blood caused by diabetes), as well as an increase in plasma PCO2 due to impaired pulmonary function. TRUE/FALSE
TRUE.
What is the function of carbonic anhydrase within the renal tubule?
Secretion of H+ ions and reabsorption of HCO3, depend critically on the presence of carbonic anhydrase in the renal tubules. After inhibition of carbonic anhydrase, renal tubular secretion of hydrogen ions and reabsorption of HCO3, would decrease, leading to increased renal excretion of HCO3, reduced plasma HCO3 conc. and metabolic acidosis.
Does acute renal failure lead to an increase in BUN?
Yes. It would as well lead to a significant increase in plasma potassium conc. due to the kidneys failure to excrete electolytes or nitrogenous waste products.
Necrosis of the renal epithelial cells causes them to slough away from the basement membrane and plug up the renal tubules. TRUE/FALSE
TRUE. The result would be an increase in hydrostatic pressure in Bowmans capsule and decreasing glomerular filtration.
The colloid osmotic pressure is determined by the protein concentration. TRUE/FALSE
TRUE. It is as well, considerably higher in the cell. The cell membrane is also impermeable relatively to K+, Na+ and CL-, and active transport mechanisms maintain low intracellular conc. of Na+ and CL-, and a high intracellular conc. of K+.
Does aldosterone stimulate Na+ reabsorption all throughout the loop of Henle?
NO. It stimulates Na+ only in the late distal tubule and collecting tubules, which together reabsorb much less than 10% of the filtered load of Na+.
In the distal tubule, in a dehydrated person, does molarity stay at 300mOsm/L?
No. Osmolarity in the early distal tubule is less than 300mOsm/L because the ascending limb of the loop of Henle and the early distal tubule are relatively impermeable to water, even in the presence of ADH.
The ascending reabsorbs Na+ to a much greater extent than does the descending limb.
List 3 factors that tend to decrease the renal excretion of calcium.
Increased PTH
Increased plasma phosphate conc.
Metabolic acidosis.
In the proximal tubule ca+ reabsorption tends to parallel sodium and water reabsorption.
A moderate degree of renal artery stenosis that reduces renal artery pressure distal to the stenosis to 85mmHg would result in an autoregulatory response that decreases afferent arteriolar resistance. TRUE/FALSE
TRUE.