L4- Roles of the kidney Flashcards
(30 cards)
In terms of net filtration pressure and GFR, what is the effect vasoconstriction of afferent arteriole
decrease net filtration pressure and GFR
In terms of net filtration pressure and GFR, what is the effect vasoconstriction of efferent arteriole
Increases net filtration pressure and GFR
Intrinsic mechanisms to control GFR
autoregulation via:
myogenic response: smooth muscles act as stretch receptors. increased bp causes stretch so smooth muscle contracts, leading to vasoconstriction of afferent arterioles.( vice versa)
tubulogloerular feedback: cells of macula densa detect increase in flow rate so send signals to juxtaglomerular cells to contract, leading to vasoconstriction of afferent arterioles.
extrinsic mechanisms to control GFR
sympathetic nervous system: intense activation of sns releases NA, which causes constriction of afferent arterioles. This can lower renal blood flow so much normal kidney function cant occur
hormones: low bp means juxtaglomerular cells release renin which produces angiotensin 2 (vasoconstrictor)
what us tubular reabsorption
movement of useful substances from renal tubule back into blood
where does most tubular reabsorption occur
most is in proximal convoluted tubule ( 70%)
methods of transport in tubular reabsorption
diffusion, osmosis, passive transport and active transport
paracellular pathway
diffusion between adjacent cells of epithelium
transcellular pathway
substance moves into epithelial cells across apiacl or basolateral membrane, diffuses through cytosol and exits across opposite membrane.
where are microvilli found
at apical surgace of cells in the Proximal convoluted tubule
filtrate leaves the bowmans capsule and enters _________
proximal convoluted tubule
what is the composition of proximal convoluted similar to
plamsa, miinus the blood cells and larger protein molecules (300mOsm/kg)
glucose transport in PCT
sodium/glucose cotransporter between lumen and epithelial.
Glucose transporter from epithelial into interstitial fluid
amino acid reabsorption in PCT
sodium/amino acid cotransporter between lumen and epithelial,
Amino acid transporter from epithelial into interstitial fluid.
H2O reabsorption to na+ reabsorption
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Paracellular reabsorption on PCT
as other solutes are reabsorbed through PCT into interstitial fluid, water follows by osmosis so conc of solutes remaining in tubular lumen increase, meaning they can diffuse into interstitial fluid down conc gradient.
filtrate leaves the proximal convoluted tubule and enters________
loop of henle
difference between descending and ascending limbs of loop of henle
different types of epithelial cells and permeability to water and solutes.
descending limb of loop of henle in terms of permeability to water
wall is permeable to water, moves by osmosis into interstitial fluid.
medullary interstitial fluid in terms of osmolality
high osmolality
thick ascending limb of loop of henle
active transport of NaCl occurs in thick section of ascending limb, the thick section is impermeable to water, so it remaines in the tubule so contents of the tubule become more dilute. NaCL conc increases in medullary interstitial fluid.
thin ascending limb of loop of henle
permeable to sodium and calcium, not perbeable to water, NaCl reabsorption increases the osmolality of interstitial fluid of inner medulla
countercurrent multiplication
concentrated medullary interstitial
salty medulla allows water rebsorption in collecting duct
conc is increased movind down medulla
filtrate more dilute at end of loop of henle than at start
distal convoluted tubule
regulates excretion of solutes and water.
