week 10 (renal) Flashcards
(22 cards)
question: what would happen if bp in body dropped by 25%?
- filtration will stop
GHP decrease -> NHP decrease -> FP stops
name: levels of control of glomerular filtration rate (3)
- autoregulation = local control
- hormonal regulation = kidneys
- autonomic regulation = sympathetic NS
explain: autoregulation of GFR
- myogenic mechanisms
⤷ changes in lumen diameter - keep GFR despite bp changes
- ex.
⤷ dilation of afferent arteriole -> increase blood in
⤷ dilation of glomerular capillaries -> more blood in (more filtration)
⤷ constriction of efferent arterioles -> decreases diameter -> increases psi -> more filtration
name: ways NS regulates after decrease in GFR
- increased stim. of thirst centers
⤷ increases fluid consumption - increased ADH prod.
⤷ increases fluid retention - increased sympathetic activation
⤷ vasoconstriction and increased cardiac output
**overall -> increase blood V and psi
explain: atrial natriuretic peptide
- released in resp. to excessive stretching in diastole
- inhibits release of ADH
⤷ prevents fluid retention
⤷ lowers blood V and psi - increases excretion of Na+ urine
- increases GFR
explain: transport across proximal convoluted tubule
- 60 - 70% of filtrate is reabsorbed
⤷ into blood - Na enters tubular cells
- Na pumped via Na/K exchanger into peritubular fluid
⤷ back into blood by diffusing into peritubular capillaries
explain: reabsorption in loop of henle
DESCENDING
- permeable to water
- water = reabsorbed
⤷ moving out bc osmosis
- V of primary urine = decreases
- primary urine -> more conc.
⤷ solute conc. increases going down the limb
ASCENDING
- impermeable to water
- ions reabsorbed (moving out)
- primary urine -> dilute
- reabsorbed ions accumulate in surrounding fluid
⤷ creates conc. gradient
**water reabsorp. later in collecting duct
explain: conc. gradient of loop of henle
- descending
⤷ more solute outside
⤷ H2O leaves -> outer conc. has less solute - ascending
⤷ less solute outside -> ions leave limb
name: functions of countercurrent mechanism of loop of henle (2)
- efficiently reabsorbs water (descending) and solutes (ascending)
- establishes conc. gradient to allow passive reabsorp. to water from tubular fluid in collecting duct area
explain: transport across distal convoluted tubule
- site of Ca reabsorption
- reabsorbs varying amount water
⤷ under stim. of antidiuretic hormone - reabsorbs Na
⤷ under stim. of aldosterone
question: diuretic vs antidiuretic?
- diuretic = stim. water excretion
⤷ more secretion - anti = reduce water excretion
⤷ more reabsorp.
question: how does ADH increase water reabsorption?
- ADH activity activates protein kinase A -> phosphorylates AQP-2 channel
⤷ increases AQP-2 channel vesicle fusion -> reduces rate of endocytosis - leads to more AQP-2 channels staying on surface
⤷ increases water permeability at collecting duct
⤷ increases water reabsorp.
question: how should be nephron be modified to allow humans to drink ocean water?
- make nephron loop longer + shorten thick ascending limb
⤷ allows more water reabsorption - shortening ascending limb = keeps more salt inside loop
⤷ don’t want the salt to be reabsorbed
**overall want less urine + more conc. urine
question: ionoconformer vs ionoregulator?
- conformer = specific ions are similar to conc. in water
- regulator = regulates own ions but make the overall osmolarity conform
⤷ ion lvls diff. but overall same osmolarity
question: hypertonic vs isotonic vs hypotonic?
- hyper = more solute outside -> water moves out
- iso = equal
- hypo = more solute inside -> water moves in
explain: elasmobranchs osmolarity
- ex. sharks, rays
- osmoconformers but ionoregulators
⤷ matches osmolarity but diff. ion conc. - salt lvls maintained low
⤷ kidney removes ions
⤷ rectal gland excretes NaCl fluids - body fluids are hyperosmotic
⤷ draws water into body
explain: bony fish osmolarity
- osmoregulators
⤷ not same as salt water - gills efflux Na and Cl
- rectal glands excrete Na in feces
name: ionic and osmotic challenges for animals in marine, freshwater, and terrestrial envrt.
MARINE
- tend to gain salt and lose water
FRESHWATER
- tend to lose salt and gain water
TERRESTRIAL
- tends to lose water
explain: ion and water balance in a freshwater org. (challenges + solutions)
- hyperosmotic to freshwater
⤷ animal has higher conc/ salts -> water coming in
CHALLENGES
- risks gaining too much water
- risks losing salt and ions
SOLUTIONS
- osmoregulate
⤷ excrete very dilute urine + transport salts back through gills
- drink less/no water
explain: ion and water balance in a saltwater org. (challenges and solutions)
- hyposmotic to sea water
⤷ osmolarity of water is higher than body
CHALLENGES
- risk of gaining too much salt
- risk of losing too much water
SOLUTIONS
- drink seawater
⤷ helps w/ V of water but still taking in salt
- osmoregulate
⤷ excrete concentrated urine + remove salt through gills
explain: ion and water balance in a terrestrial org. (challenges and solutions)
CHALLENGES
- losing too much water
⤷ desiccation
- gaining too much salt
SOLUTIONS
- drink more water and salts in diet
- osmoregulate
⤷ excrete concentrated urine + remove salts through renal sys.
name: example of terrestrial animal osmoregulating to remove salts
- lizard dude
- sprayed out stuff
⤷ was salt - salt nasal glands eliminate excess salt
⤷ NaK ATPase and NaKCl cotransporter on membrane of renal tubule
