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59 Cards in this Set
- Front
- Back
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how compute new osmolarity/vol in ICF?
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total osmole / new total vol -> new osmolarity. icf osmoles/? L = new osmolarity
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actual blood vol from measured blood vol eqn
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actual blood vol = 1.1 x measured blood vol
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measuring plasma vol eqn
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(find plasma vol from C1V1=C2V2 then)
blood vol = plasma vol x 100/(100-.87Hct) measured Hct is greater than true Hct (Hct greater in large vessels, RBCs not completely packed when spun down) |
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what can you use to measure EC space
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inulin (underestimates) or Na (overestimates). vol = amount/conc of material you used
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interstitial fluid =
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ISF = ECF - plasma
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ECF has a higher conc of
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Na, Cl
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ICF has a higher conc of
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K, HPO4
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blood that isn't filtered thur glom continues along
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vasa recta (peritubular circulation)
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where are macula dense
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are of DCT near bowman's capsule
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normal GFR is
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125 ml/min
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normal renal plasma flow is
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625 ml/min
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how much plasma filtered / day?
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180L (GFR x 60min x 24hr)
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plasma vol
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3L
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urine production is normally
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1.4L/day
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freely filtered stuff includes
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ions, wast (urea, creatinine, organic acids), glucose, aa, water
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where is neg charge found on glom?
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endothelial cells of caps (outside glom). lined w/ sialic acid
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net filtrartion pressure is normally
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24 mmHg at afferent end
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net filtration pressure eqn simplified to
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NFP = Pc - Pbc -'pi'c
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what does the filtartion coefficient depend on
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proportional to surf area and permeability of glom mem (mesangial cells)
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gfr eqn w/ nfp
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gfr = nfp x Kf
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what factors can inc gfr?
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inc in pressure (afferent dilation or eff constriction?). relaxation of mesagnial cells (higher permeability)
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what factors dec gfr?
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obstruction in renal system (inc press in bowman's). inc in plasma oncotic press. dec in RPF (faster rise of oncotic press)
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aff constriction
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dec Pgc, dec rbf
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eff constriction
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inc Pgc, dec rbf
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aff and eff constriction
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Pgc same, rbf down more
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gfr autoregulation
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myogenic (aff art sm vasoconstrict when stretched, diverts blood flow), tubulo-glomerular feedback (granular and macula densa cells sense graeter flow, cause aff art constriction)
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Na absoprtion
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prox tub 65% [Na enter passively thru carrier. exit active trans], ?CCT principal cells [Na enter simple diffusion, leave Na/K pump]
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glucose absorption
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all reabsorbed in PT. comes in w/ Na. simple diffusion out
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excretion =
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excretion (Mg/min) = urine conc (mg/ml) x vol rate (ml/min)
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threshold (ex: glucose)
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plasma glucose level at which glucose first appears in urine
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what is used to measure rpf?
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PAH (exogenous). it is secreted
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clearance eqn
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Cx (clearance) = Ux (urine conc) x V (urine flow) / Px (plasma conc)
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what is clearance
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vol of plasma that is cleared of substance per min
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clerance eqn in words
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clearance = amt of substance excreted into urine from plasma / amt that was initially in the plasma
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when will a substance demonstrate gfr? what qualities?
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freely filtered, neither absorbed nor secreted, not synth or metabolized by kidneys. [filtered load then = excretion]
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what substance can show gfr?
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inulin, creatinine
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what are qualities of substance to find rpf?
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filtered and secreted, not reabsorbed [amt substance entering renal artery then = excretion of subst]
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what do you use to measure rpf?
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PAH
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how do you calculate rbf?
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ERBF = Upah x V / Ppah. RPF = Cpah/.9 (only 90% pah that enters is excreted) RBF = RPF/1-Hct
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fractional excretion eqn
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FE = Cx / Cinulin . FE>1 is secretion, FE<1 is reabsorption
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creatinine qualities (absorption etc, how compares to value)
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estimates gfr. constant conc normally. freely filtered but SOME secretion -> gfr is OVER-estimated
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how creatinine / day? normal plasma value?
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1800 mg/day. plasma has 10 mg/L
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elevated creatinine means
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some kind of renal failure
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where is protein reabsorbed? how?
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prox tube. mostly all of it except 100mg/day. endocytosis
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where is urea reabsorbed? how?
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50% in PT, also in medullary CT. via diffusion
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where are organic nutrients (aa, ?glucose) reabsorbed? how?
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in prox tub, active transport
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how does protein reabsorption happen?
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endocytosis (proteins, insulnie). or degradation at brush border (small simple ones like AII)
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does a polar or nonpolar molecule get reabsorbed better?
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nonpolar
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weak acid in acidine urine is...
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(HA) nonpolar -> reabsorbed
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weak base in acidic urine is...
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polar-> secreted
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pt ODs on asipirin (acidic), how tto enhance secretion?
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alkalinize urine, make drug polar, thus secreted
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filtration frac eqn and value
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ff=gfr/rpf=125/600=.20
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renal flow eqn (using vessel pressures)
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flow = mean art press - vein pressure / R
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sequence of events in autoregulation (inc press)
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inc renal art press->inc P glom cap->inc fliud to macula dense (inc Na and Cl?)->inc aff constriction. so rbf and gfr do NOT inc since aff resistance prevents inc in gfr and glom hydrostatic press
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what happens w/ hemorrhage
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dec in art BP (carotid sinus and aortic baroreceptors respond)->inc symp to renal and inc epi->constriction of rena aff and eff-> dec in RBF and GRF (ff inc since rpf dec more than fgr)
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what happens to ff w/ symp input?
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ff inc (rpf dec more than gfr). conserve more fluid in plasma to help restore bp
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what happens in renin-angiotensin sys cell-wise
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symp nerve innervate on granular cells, and release renin with dec in BP. also, dec in BP causes granular cells to release renin(act like baroreceptors)
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effects of renin-angiotensin
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rbf and gfr dec, ff inc, filtration coefficient dec.
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what do prostaglandins do
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dampen effects of AII. theyare vasodilators
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