bsci202 study qguide 3

bsci202 study qguide 3 - The Urinary System: - Functions o...

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The Urinary System: - Functions o Regulate aspects of homeostasis Water balance – ADH Acid-base balance in the blood by regulating plasma pH Regulate plasma ionic composition, electrolytes such as: calcium, sodium, potassium Regulate blood pressure and blood volume by regulating plasma volume and plasma osmolarity – ADH Red blood cell production: secrete erythropoietins (stimulates RBC production) and rennin (angiotensinogenase) Activate vitamin D3 (calcitriol) – allows for the re absorption of calcium o Elimination of waste products Nitrogenous wastes Toxins Drugs - Organs o Kidneys: formulate urine o Ureters: transport urine from the kidney to the bladder o Bladder: stores urine o Urethra: excretes urine - Nephron Types and aspects o The structural and functional unit of the kidney o Knot of capillaries o Responsible for forming urine o Renal tubule extends from glomerular capsule and ends at the collecting duct Glomerular (Bowman’s) capsule First part of the renal tube Glomerulus sits within o Fed and drained by arterioles
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o Afferent arterioles feed it o Efferent receive blood that has passed through it Proximal Convoluted tubule Loop of henle Distal convoluted tube o Cortical nephrons Located in the cortex Includes most nephrons o Juxtamedullary nephrons are found at the boundary of the cortex and medulla - Urine formation o Glomerular filtration Water and solutes smaller than proteins are forced through the capillary walls and pores of the glomerular capsule into the renal tubule Blood pressure maintenance 80-100 o Reabsorption Substances transported out of filtrate, into the tubules and then enter the peritubluar capillaries o Secretion From peritubuluar capillaries to tubules Secreted by tubular cells into the filtrate Filtrate looks very similar to plasma but has no cells or proteins o Excretion From tubules out of the body - Renal handling of solute o If amount of a solute excreted per minute is less than filtered load solute was REABSORBED o If amount of solute excreted per minute is greater than filtered load solute was SECRETED - Excretion Rate (need to know the process)
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o Amount of a substance excreted = amount filtered + amount secreted – amount reabsorbed o Amount excreted depends on three factors Filtered load Secretion rate Reabsorption rate - Clearance: a measure of kidney function o Volume of plasma from which a substance has been removed by kidneys per unit time o Clearance of substance freely filtered, fully secreted, and not reabsorbed = renal plasma flow rate o Therefore the amount excreted = amount contained in volume of the plasma that entered the kidneys o Concentration in urine = the same as in plasma Enulin – freely filtered, reabsorbed, and secreted - Micturition (voiding) o Urine formed in renal tubules o Fluid drains into renal pelvis and into ureter o Ureters lead to bladder o Bladder stores urine until it is excreted
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This note was uploaded on 12/01/2010 for the course BSCI 202 taught by Professor Opoku during the Fall '08 term at Maryland.

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bsci202 study qguide 3 - The Urinary System: - Functions o...

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