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Physiology - Renal Difficult questions
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roles of kidney
osmolarity depends on?
number not size of solute
normal saline
0.9g/dl
or
9%
non penetrating solutes
ethanol
urea
metabolised glucose (synthesized in cell)
difference between osmolarity and tonicity
osmolarity= diffusion of water down is gradient
tonicity= movement of water inresponse to changes in osmolarity
forces governing movement
across capillary walls:capillary pressure osmotic pressure, tissue pressure (starling forces)
across cell membrane
: osmotic effects
intrinsic control of GFR
myogenic
: sensed by high BP stretching stretch receptors which result in vaso constriction of Afferent arterioles
tubuloglomerular feedback flow sensed by macula densa which gets paracrine hormones to constrict Afferent arterioles
Extrinsic control of GFR
sympathetic innervation - reduces GFR by constricting Afferent arteriole
occurs during a hemmorage
differences between dectecting GFR and RPF
GFR measured by
: substance that is not secreted, filtered or reabsorbed (tested with mainly creatinine or insulin)
clearance
: volume of filtered fluid with all solutes removed from it
RPF measured by
: substance that is both filtered and secreted but not absorbed (measured by pah) (a protein)
total clearance
: no agent remains in renal vein
Filtration Forces
PROMOTED by
: blood pressure
OPPOSED by
: osmotic pressure (more proteins reabsorbed in blood here) and tubule pressure (fluid already in capsule)
Renal Plasma Flow Calculations
RPFxP(pah)=U(pah)xV/t
or
RPF=[U(pah)xV/t] P(pah)
Renal Blood Flow Calculations
RBF =RPF/1-HTC (hematocrit)
Calculating GFR
filtration rate x Plasma conc = Urine conc x Urine Volumeaka (mass filtered) = (mass excreted)
which side of the proximal tubule has micro villi
luminal side
Symport example
Na/glucose co transport
Antiport example
Na/H co transport
Secondary Active Transport Example
Na gradient set up by Na/K ATPase (basolateral)
solvent drag example
sodium glucose linked transporter
Organic Ion Secretion
organic ions (eg. penicillin, aspirin) are actively secreted into the filtrate
un-ionized substances first converted to ionized form in liver and then secreted
ionized substances remain in filtrate
still have to do lecture 4
what determines ECF osmolarity
ADH
what regulates ECF volume
renin angiotensin and aldosterone
(RAA) System
low A2 constricts the
efferent arteriole
increases GFR
what creates new Na channels and Na/K ATPase
ALDOSTERONE
what promotes natriuresis (Na excretion) and Na reabsorption from collecting duct
ANH
lecture 6
lecture 7 and 8
Author
9spr
ID
70806
Card Set
Physiology - Renal Difficult questions
Description
Difficult questions
Updated
2011-03-05T04:30:53Z
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