physiology Flashcards
Total body water (TBW) - proportion
60% of body mass
Non water mass (NWM) - proportion
40% of body mass
total body water mass and non water mass if Body mass is 70kg
- total body water –> 60% of body mass = 42kg = 42L
- non water mass –> 40% of body mass = 28kg
Total body water (TBW) is divided to … (and proprotions)
- extracellular fluid (ECF) –> 1/3
2. intracellular fluid (ICF) –> 2/3
extracellular fluid (ECF) in a body mass 70kg
1/3 of 60% body mass –> 20% of body mass –> 14kg
–> 28L
intracellular fluid (ICF) in a body mass 70kg
2/3 of 60% body mass –> 40% of body mass –> 28kg
–> 28L
extracellular fluid (ECF) vs intracellular fluid (ICF) according to proportion in body mass
extracellular fluid (ECF) --> 20% intracellular fluid (ICF) --> 40%
extracellular fluid (ECF) is divided to (proportions and L in body mass 70 kg)
- interstitial fluid –> 75% ECF –> 10.5 kg –> 10.5 L
2. plasma –> 25% ECF –> 3.5kg –> 3.5 L
RBC volume
2.8 L (part of intracellular fluid)
blood conistis of (and volumes)
RBCs (2.8.L) and plasma (3.5L) –> 6.2 L
Normal HCT (calculation and alternative calculation)
RBC volume/blood volume = 2.8/6.2 = 45%
altenatively –> HCT(%) = 3X(Hb) in g/dL
Plasma volume can be measured by
radiolabeling albumin
or Evans blue (it binds albumin)
Extracellular volume can be measured by
inulin or manitol, or sulfate
osmolarity is the
measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution
osmolarity - normal range
285-295 mOsm/kg H2O
Glomerular filtration barrier is responsible for
filtration of plasma according to size and net charge
Glomerular filtration barrier is composed of (and role of every component)
- fenestated capillary endothelium –> SIZE BARIER
- fused basement membrane with heparan sulfate –> NEGATIVE CHARGE AND SIZE BARRIER
- epithelial layers consisting of podocyte foot processes –> NEGATIVE CHARGE BARRIER
Glomerular filtration barrier - components for size barrier and components for charge barrier
size: 1. fenestated capillary endothelium 2. fused basement membrane
charge: 1. fused basement membrane 2. epithelial layers consisting of podocyte foot processes
Charge barrier is lost in ….(and clinical presentation)
nephrotic syndrome –> 1. albuminuria 2. hypoproteinemia
3. generalized edema 4. hyperlipidemia
renal clearance - definition
volume of plasma from which the substance is completely cleared per unit (from renal)
renal clearance - calculation
Cx=Ux.V/Px CX=Clearance of x (ml/min) Ux=urine concentration of x (mg/ml) Px=plasma concentration of X (mg/ml) V=urine flow rate (ml/min)
if renal clearance equals/smaller/bigger than GFR
Cx smaller: if smaller net tubular reabsorption of X
Cx bigger: net tubular secretion of X
Cx=GFR: no net secretion or reabsorption
Inulin clearance can be used to … (why)
caclulate GFR because it is freely filtered and is neither reabsorder nor secreted
Glomerular filtration rate (GFR) estimates
how much blood passes through the glomeruli each minute.
GFR calculation
GFR = inulin clearance = (Urine concentration of inulin x urine flow rate) / plasma concentration of inulin = Starling equation
Normal GFR =
100ml/min
Starling equation
GFR= Kf ((Pgc - Pbs) - (πgc-πbs)) gc: glomerular capillary bs: Bowman space Kf: filtration constant πbs = 0
creatinine clearance - clinical relevance
it is an approximate measure of GFR –> slightly overestimates GFR because creatinine is moderaterly secreted by renal tubules
chronic kidney disease - GFR measure
incremental reductions in GFR define the stages of chronic kidney disease
creatinine serum concentration
0.6-1.2mg/dL or 53-106μmol/L
Effective renal plasma flow (eRPF) is used to
calculate renal plasma flow (RPF) and hence estimate renal function.
Effective renal plasma flow (eRPF) can be estimating using … (why)
para-aminohippurinc (PAH) clearance because filtration and secretion is nearly 100% excretion of all PAH that enter kidney
Effective renal plasma flow (eRPF) calculation
para-aminohippurinc (PAH) clearance = Upah x V/Ppah
renal blood flow (RBF) is the
volume of blood delivered to the kidneys per unit time
renal blood flow (RBF) - calculation
renal blood flow (RBF) = RPF/(1-Hct)
1-HcT=plasma
eRPF vs true renal plasma flow
eRPF underestimates true renal plasma flow slightly
renal filtration fraction - definition
is the ratio of the glomerular filtration rate (GFR) to the renal plasma flow (RPF)
Renal filtration fraction - caclulation and normal value
FF=GFR/RPF = 20% (normally)
Filtered load calculation
Filtered load (mg/min) = GFR(ml/min) x plasma concentration (mg/ml)
effect of NSAID on renal function
NSAIDs inhibit prostagladins (that preferentially dilated afferent arteriole and increase RPF and GFR, not the FF)
- -> constriction of afferent arteriole –> decrease of RPF and GFR, not the FF –> IN LOW RENAL BLOOD SATES
- -> ACUTE RENAL FAILUE
effect of ACE inhibitors on renal function
ACE inhibitors decrease angiotensin 2 (that preferentially constricts efferent arteriole and decrease RPF, increase GFR and increase FF) –> dilation of efferent arteriole –> increas RPF, decreased GFR, so decrease FF)
prostagladins vs angiotensin 2 on renal function
- prostagladins –> preferentially dilated afferet arteriole and increase RPF and GFR, not the FF
- angiotensin 2 –> inhibits preferentially constricts efferent arteriole and decrease RPF, increase GFR and increase FF
Afferent arteriole constriction - GFR, PRF, FF?
GFR: decreased
RPF: decreased
FF: -
efferent arterile constriction - GFR, PRF, FF?
GFR: increased
RPF: decreased
FF: increased
increased plasma protein concentration - GFR, PRF, FF?
GFR: decreased
RPF: -
FF: decreased
decreased plasma protein concentration - GFR, PRF, FF?
GFR: increased
RPF: -
FF: increased
constriction of ureter - GFR, PRF, FF?
GFR: decreased
RPF: -
FF: decreased
dehydration- GFR, PRF, FF?
GFR: decreased
RPF: decreased
FF: INCREASED
filtration fruction on dehydration?
increased
renal - filtration, reabsorption, secretion excretion???
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renal - Filtered load - calculation
GFR X plasma concentration