Flashcards in physiology final Deck (362)
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What is the job of the kidneys?
maintain the constancy of the body's internal environment
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How do they accomplish this?
By regulating the volume and composition of extracellular fluids
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What do they use to excrete metabolic end products?
Nephrons
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What else are the kidneys involved with?
regulation of the total amount of many important substances in the extracellular matrix.
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What are the 7 main functions of the kidneys?
1- regulation of the concentration of numerous ions. 2- excretion of organic compounds. 3- fluid balance. 4- acid-base balance. 5- blood pressure regulation. 6- erythrocyte volume regulation. 7- Vitamin D activation
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How do the kidneys accomplish #1? (from previous ?)
excretion or preservation of Na, Cl, K, Ca, PO4 - balance their intake, production or excretion through other routes
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How is #2 accomplished?
1) elimination of substances like urea and creatinine in amounts equaling their production rates. 2)elimination of drugs, FO, and toxins
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#3?
1)regulate water. 2) regulate osmotic pressure of EC fluids. 3) produce urine
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#4?
excretion of H+ or HCO2 as needed
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#5
renin-angiotensin system and renal-body fluid balance system
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#6>
through formation and release of erythropoetin
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#7?
vitamin D hydroxylation to render it useful.
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How much more salt than water do humans typically consume each day?
20-25%
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How is that excess salt/water disposed of?
Urine
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What sensors determine how much is to be excreted?
water volume sensors, salt sensors, osmolality sensors,
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How do these sensors instruct the kidneys on what to do?
via hormones.
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Where does all the action in the kidney take place?
Nephrons
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What is a nephron encased in?
a maze of peritubular capillaries
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What are the components of a nephron?
1) Glomerular capsule, 2) PCT, 3) loop of Henle, 4) DCT, 5) collecting duct
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What are the components of the vasculature of a nephron?
1) intralobular artery. 2) afferent arteriole 3) glomerulus 4) efferent arteriole 5) peritubular capillaries 6) venule and intralobular vein
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What are the 3 versions of a nephron?
1) superficial. 2) mid-cortical. 3) juxtamedullary
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What 3 activities do kidneys engage in?
1) filtration 2) reabsorption 3) secretion
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Where is the bulk of the work done?
in glomeruli and PCTs
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What remains in the final end of the tubules?
urine
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How does blood enter the kidney and nephron?
through Renal artery
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What does the blood return to circulation through?
renal vein
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The nephron is said to "clear" what?
the blood of unwanted substances - removes unwanted agents from the plasma
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What is clearance?
the amount of plasma cleared of a given substance
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How can glomerular filtration rate be measured?
by looking at the clearance of something that is freely filtered and not reabsorbed at all.
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