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Urinary System
BYU PdBio 305 Rhees Urinary System
| Question | Answer |
|---|---|
| urinary system consists of what | kidneys, ureters, urinary bladder, urethra |
| urinary system does what | regulates water balance, electrolyte balance, acid-base balance, rids body of waste of metabolism, foreign chemicals, drugs, and food additives, and serves a s a minor endocrince organ and produces renin and erythropoietin |
| where are kidneys located | between the levels of the 12th thoracic and the 3rd lumbar vertabrae |
| hilus | concave medial surface of kidney |
| renal cortex | outer portion of kidney which contains capillary tufts and convoluted tubules |
| renall medulla | inner portion of kidney and contains renal pyramids and renal columns |
| acute renal failure | sudden loss of kidney function, usually associated with shcok or intense renal vasoconstriction, that lasts from a few days to many weeks |
| cystitis | inflammation of the urinary bladder |
| hematuria | blood in the urine |
| hemodialysis | method of clearing waste products from the blood in which blood passes by the semipermeable membrane of the artificial kidney and waste products are removed by diffusion |
| nocturia | night urination |
| oliguria | urinary volumes less than 500ml/day |
| polyuria | excessive urine output |
| uremia | retention of urinary constituents in the blood, owing to kidney dysfunction |
| Nephron and parts | functional unit of the kidney, consisting of the glomerulus, glomerular capsule (Bowman's capsule), the proximal convoluted tubule, the nephron loop (loop of Henle), the distal convoluted tubule, and the collecting duct |
| how many nephrons/kidney | over 1 million nephrons per kidney |
| glomerulus | consists of a network of about 50 capillaries. The capillary endothelium lining the glomerulus has many circular fenestrations, or pores, which are larger and more numerous than anywhere else in body. |
| permeability of glomerulus | 100-1000X more permeable than typical capillaries |
| glomerular capsule (Bowman's capsule) | double-walled cuplike structure composed of squamous epithelium. Outer layer is continuous w/ the proximal tubule. Inner layer is composed of podocytes that are closely associated with the glomerular capillaries |
| proximal convoluted tubule | single layer of cuboidal cells containing microvilli (as a brush border) that greatly increase the surface are. Terminates in the first portion of the nephron loop, called the descending limb of the nephron loop |
| nephron loop | has descending and ascending thin limbs and an ascending thick portion. Thin segments are lined w/ flat squmous cells that lack microvilli, as do the cuboidal cells that compose the thick segment, which runs between the afferent and efferent arterioles |
| distal convoluted tubule | begins at the macula densa, a mass of specialized epithelial cells of the tubule wass, located next to the afferent arteriole. Shorter and less microvilli than the proximal confoluted tubule. last part of nephron and empties into the collecting duct |
| 3 major fxns of nephron | glomerular filtration, tubular reabsorption, tubular secretion |
| glomerular filtrate | portion of the blood plasma that enters the capsule. amounts to about 180L/day=45 gallons/day |
| mechanisms that cause such large amounts of glomerular filtrate | 1)high hydrostatic pressure of the blood (45 to 60 mmHg) in the glomerulus 2)large numbers of pores, which are larger than most pores in blood capillaries |
| substances in blood that are in glomerular filtrate and those that aren't | in filtrate: water, electrolytes, glucose, amino acids, urea, hormones, vitamins; not in: plasma proteins, RBC's, WBC's and platelets because they're too big |
| presence of RBC's or protein in the urine indicates what? | hydrostatic pressure in the glomerular capillaries is excessively high or that there is a defect in the glomerular membrane |
| glomerular filtration rate (GFR) | about 120 ml/minute, 7.5 L/hour, 180 L/day |
| regulation of GFR | via vasoconstriction and vasodilation of afferent arterioles results from both extrinsic (sympatheti nerves) and intrinsic (locally produced chemicals) mechanisms |
| Measurement of GFR | measure excretion and plasma concentration of a substance that is freely filtered into Bowman's capsule and is not secreted or reabsorbed by tubules. measure amount of substance in urine per unit time |
| inulin | a polymer of fructose (extracted from plants). since it is not produced by the body and not secreted or reabsorbed it is used to measure the GFR |
| GFR equation | ((urine volume (ml/min))(inulin conc. in urine (mg/ml)))/(inulin conc. in plasma (mg/ml)) |
| tubular reabsorption | transfer of fluid and solutes out of the lumen of the nephron through the interstitial space and into the pertitubular capillaries |
| % of filtrate reabsorbed from the renal tubules | 99% |
| % of water reabsorbed by tubular reabsorption | 99% |
| % of sodium reabsorbed by tubular reabsorption | 99.5% |
| % of glucose reabsorbed by tubular reabsorption | 100% |
| % of urea reabsorbed by tubular reabsorption | 50% |
| % of phenol reabsorbed by tubular reabsorption | 0% |
| tubular reabsorption occurs throughout the "blank", but primarily in the "blank" portion | renal tubules, proximal convoluted |
| trans-epithelial transport | transport of substances by tubular reabsorption |
| % of reabsorbed material that is reabsorbed through the proximal convoluted tubule | 80% |
| % of reabsorbed material that is reabsorbed through the nephron loop | 6% |
| % of reabsorbed material that is reabsorbed through the distal convoluted tubule | 9% |
| % of reabsorbed material that is reabsorbed through the collecting duct | 4% |
| parts of reabsorption physiology that are under ADH control | distal convoluted tubule and collecting duct |
| two ways substances are reabsorped by the nephron | diffusion (H2O and urea) and active transport (glucose) |
| aldosterone | regulates the reabsorption of Na+ in the distal and collecting duct (renin-angiotensin-aldosterone system) |
| where is glucose reabsorbed? | proximal tubule |
| normal glucose concentration in blood | 100mg/100ml |
| transport maximum (Tm) | the concentration of transported molecules needed to saturate the carriers and thus achieve maximal transport rate (especially used with glucose levels) |
| Tm of glucose | 375mg/minute |
| tubular secretion | the secretion or movement of substances from the peritubular capillaires into the lumen of the tubule |
| most important substances secreted in tubular secretion | hydrogen ions (H+), potassium ions (K+), and some organic anions (penicillin) |
| where are H+ ions secreted? | in all tubular regions |
| where are K+ ions usually reabsorbed and secreted? | reabsorbed in the proximal tubule and actively secreted in the distal tubule and collecting duct |
| aldosterone's effect on Na+ and K+ | stimulate K+ secretion and Na+ reabsorption |
| how do the kidneys control acid-base balance? | secretion of H+ ions into the tubules and the reabsorption of bicarbonate |
| are the amounts H+ secreted and bicarbonate reabsorbed interdependent? | yes |
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