Pathology

Question 1

60-40-20 Rule

Answer 1

60%totalbodywater

40%ICF,mainlycomposedofK+,Mg2+,organicphosphates(eg,ATP)

20%ECF,mainlycomposedofNa+,Cl–,HCO3–,albumin

Question 2

Mesurement of ICF and ECF

Answer 2

Plasma volume can be measured by** radiolabeling albumin.**

Extracellular volume can be measured by inulin or mannitol.

Question 3

Clearance (Cx) relation to substance x with excretion and reabspt.

Answer 3

Cx<GFR:net tubular reabsorption and/or not freely filtered.

If Cx>GFR:net tubular secretion of X.

If Cx=GFR:no net secretion or reabsorption.

Question 4

What mesures best GFR?

Answer 4

=**Inulin clearance can be used to calculate GFR because it is freely filtered and is neither reabsorbed nor secreted
-Normal GFR≈100mL/min

Question 5

What is used to aprox GFR value?

Answer 5

Creatinine clearance is an approximate measure of GFR.Slightly over estimates GFR because creatinine is moderately secreted by renal tubules.

Question 6

RBF regulation mechanism (2)

Answer 6

1.Myogenic:arterial pressure stretch of afferent arteriole–> mechanical activation of vascular smooth muscle–> vasoconstriction of afferent arteriole –>REDUCES RBF.
2.Tubuloglomerular: incr NaCl or tonicity of the filtrate sensed by macula densa cells–> paracrine-driven vasoconstriction of afferent arteriole–> decr RBF.

Question 7

What do we use for RBF calculation?

Answer 7

Effective renal plasma flow(eRPF) can be estimated using para-amino hippuricacid(PAH) clearance. Between filtration and secretion, there is nearly 100% excretion of all PAH that enters the kidney.