Renal USMLE Flashcards
ureters pass _______ uterine artery and ______ ductus deferens (retroperitoneal)
UNDER,UNDER
mneu: water (ureters) UNDER the bridge (artery, ductus deferens).
total body weight is ____% water
60
total body water is ___ intracellular fluid
2/3
total body water is 1/3 extracellular fluid what portion of this is plasma volume
1/4
ICF=
TBW-ECF
interstitial volume-
ECF-PV
60-40-20 rule (% of body weight)
60% total body water
40% ICF
20% ECF
plasma volume can be measured by this
radiolabeled albumin
extracellular volume can be measured by this
inulin
Cx=
UxV/P=volume of plama from which the substance is cleared completely per unit time
Cx=clearance of X
Ux=urine concentration of X
Px=Plasma concentration of X
V=urine flow rate
if Cx < GFR, then there is net tubular ________ of X
resorption
if Cx > GFR, then there is net tubular ________ of X
secretion
if Cx = GFR, then ___________
no net secretion or reabsorption
glomerular filtration barrier is responsible for filtration of plasma according to these 2 factors
size and net charge
what is the glomerular filtration barrier composed of
1) fenestrated capillary endothelium (size barrier)
2) Fuse basement membrane with heparan sulfate (negative charge barrier)
3) epithelial layer consisting of podocyte foot processes
what barrier of the glomerular filtration barrier is lost in nephrotic syndrome
charge barrier
what are some symptoms of nephrotic syndrome
albuminuria, hypoproteinemia, generalized edema, and hyperlipidemia
what is used to calculate GFR because it is freely filtered and is neither reabsorbed nor secreted
inulin
creatinine clearance is an approximate measure of what
GFR
GFR=
U(inulin)xV/P(inulin)=C(inulin)
effective renal plasma flow (ERPF can be estimated using _____ because it is both filtered and actively secreted in the proximal tubule. All _____ entering the kidney is excreted.
PAH
ERPF=
U(PAH)xV/P(PAH)=C(PAH)
RBF=
RPF/1-Hct
ERPF underestimates true RPF by how much?
~10%
filtration fraction (FF)=
GFR/RPF
what effect will afferent arteriole constriction have on
RPF:
GFR:
FF (GFR/RPF):
RPF:↓
GFR:↓
FF (GFR/RPF):NC
what effect will efferent arteriole constriction have on
RPF:
GFR:
FF (GFR/RPF):
what effect will afferent arteriole constriction have on
RPF:↓
GFR:↑
FF (GFR/RPF):↑
what effect will increased plasma protein concentration have on
RPF:
GFR:
FF (GFR/RPF):
RPF:NC
GFR:↓
FF (GFR/RPF):↓
what effect will decreased plasma protein concentration have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR: ↑
FF (GFR/RPF):↑
what effect will constriction of ureter have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR:↓
FF (GFR/RPF):↓
free water clearance
C(H2O)=
V-C(osm)
V=urine flow rate
glucose at a normal level is completely reabsorbed where
proximal tubula
at plasma glucose of _____, glucosuria begins (threshold)
200mg/dL
at plasma glucose level of ______, transport mechanism is saturated (Tm)
350 mg/dL
amino acid resorption occurs by at least 3 distinct carrier systems, with competitive inhibition within each group. Secondary active transport occurs in the _________ and is saturable.
proximal tubule
what effect will decreased plasma protein concentration have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR:↑
FF (GFR/RPF):↓
what effect will constriction of ureter have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR:↓
FF (GFR/RPF):↓
free water clearance
C(H2O)=
V-C(osm)
V=urine flow rate
glucose at a normal level is completely reabsorbed where
proximal tubula
at plasma glucose of _____, glucosuria begins (threshold)
200mg/dL
this part of the nephron is called the “workhorse of the nephron”
early proximal convuluted tubule.
the early proximal convuluted tubule resorbes all of these 2 things and most of these 3 things
all of glucose and amino acids
most of the bicarb, sodium, and water
the early proximal convuluted tubule secretes this which will act as a buffer for secreted H+
ammonia
this part of the nephron passively reabsorbs water via medullary hypertonicity (impermeable to sodium)
thin descending loop of Henly
this part of the nephron actively reabsorbs Na+, K+, and Cl- and indirectly induces the reabsorption of Mg++ and Ca++. It is impermeable to H2O
Thick ascending loop of Henle
the early distal convuluted tubule actively reabsorbs these 2 ions. Here reabsorbion of Ca++ is under the control of PTH
Na+, Cl-
the collecting tubules resorb Na_ in exchange for secreting K+ or H+. This is regulated by this hormone
aldosterone
in the collecting tubules resorption of water is regulated by this hormone
ADH (vasopressin)
osmolarity of medulla can reach ______mOsm
1200
this is released by the kidneys upon sensing decreased BP
renin
renin cleaves angiotensinogen to this
ATN I (a decapeptide)
ATN I is cleaved by this enzyme, primarily in the lung capillaries and elsewehere, to ATN II (an osctapeptide)
Angiotensin-converting enzyme (ACE)
what are the actions of angiotensin II
1) potent vasoconstriction
2) release of aldosterone from the adrenal cortex
3) release of ADH from posterior pituitary
4) stimulates hypothalamus to increase thirst
what is the overal purpose of ATN II
increase intravascular volume and BP
this peptide released from atria may acti as a “check” on the renin-angiotensin system (e.g., in heart failure).
ANP
these are modified smooth muscle cells of afferent arteriole
JG cells
this is a Na+ sensor and part of the distal convoluted tubule
macula densa
JG cells secrete this in resoponse to low renal blood pressure, low Na+ delivery to distal tubule, and increased sympathetic tone
renin
what does the juxtaglomerular apparatus (JGA) consist of
JG cells and macula densa
when the JG cells secrete renin what does this lead to
increase in ATN II and aldosterone
JGA activates the renin-angiotensin system in defence of this
glomular filtration rate
juxta means
close by
Endocrine fxs of kidney: endothelial cells of peritubular capillaries secrete this in response to hypoxia
erythropoeietin
Endocrine fxs of kidney: conversion of 25-OH vit D to ________ by 1alpha-hydroxylase, which is activated by PTH
1,25-(OH)2 vit D
Endocrine fxs of kidney: JC cells secrete ____ in response to decrease renal arterial pressure and increase renal sympathetic discharge (B1 effect)
renin
Endocrine fxs of kidney: secretion of _________ that vasodilate the afferent arterioles to increase GFR
prostaglandins