GMS 6401 FINAL EXAM QUESTIONS WITH
DETAILED VERIFIED ANSWERS
The kidney consists of specialized vascular and tubular structures (the
nephron) which collaborate in the production of urine: Ans: the
glomerular capillary is surrounded by an epithelial structure which forms
the beginning of the tubule
A diagnostic renal clearance experiment is conducted and the following
steady state (= equilibrium) measurements are obtained on a 34 year old
male subject, weighing 60 kg (assume that the renal plasma flow (RPF) is
the same as the effective renal plasma flow (ERPF)
Urine inulin = 200 mg/100mlPlasma inulin = 4 mg/100ml.Urine flow (V)
= 2ml/minUrine PAH = 1200 mg/100mlPlasma PAH = 6 mg/100ml Ans:
GFR = 100 ml/min
200/4 x 2 ml/min = GFR = 100 ml/min
ERPF = 1200/6 x 2 ml/min = 400 ml/min
FF= GFR / ERPF = 100/400 = 0.25
Any substance which is freely filtered at the glomerulus, is reabsorbed
and is not secreted, will have a renal clearance that is: choose one best
answer. Ans: less than the clearance of inulin
- a fractional clearance (ratio of clearances of substances to inulin) < 1.0
indicates net tubular reabsorption of freely filtered substances
An increased protein excretion (proteinuria) can indicate glomeruluar
damage. Which of the following changes are likely to cause proteinuria?
Choose 1 best answer: Ans: loss of nephrin from the epithelial slit pore
diaphragm
- nephrin is an essential protein & mutations are associated with heavy
proteinuria
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Maintenance of a high glomerular filtration rate (GFR) is required for
optimal kidney function. Which of the following options would be most
likely to associate with a below optimal GFR in man? Ans: a low
glomerular capillary water permeability
A selective increase in renal plasma flow (RPF) due to parallel relaxation
of the afferent and efferent arterioles leads to: Ans: a rise in GFR with no
change in filtration fraction; parallel relaxation of afferent & efferent
arterioles allows flow to increase (due to fall in renal vascular resistance)
without a change in glomerular blood pressure or filtration fraction
an increase in renal blood flow will lead to which of the following changes
within the kidney: Ans: increased total renal oxygen consumption but
little change in the renal venous oxygen content (arterial - venous
difference)
- more Na filtered so more to reabsorb so total renal oxygen consumption
will increase but because this is matched by the increased RBF, the
oxygen extraction (A-V difference) across the kidney will stay about
constant
in which tubule segment is there active sodium reabsorption by the
Na/K/2Cl (NKCC2) transporter but never any water resabsorption? Ans:
thick ascending limb of the loop of Henle
the release of renin from the kidney, into the circulation is stimulated by
Ans: a fall in renal perfusion pressure is one of the volume depletion
signals that stimulate renin release
an extracellular fluid volume expansion leads to Ans: increased right
atrial pressure - signal to ANP release
a reduction in sodium excretion occurs when Ans: Septic shock occurs -
when septic shock develops the perceived fall in circulating blood volume
leads to excessive Na retention and therefore a fall in Na excretion
an increased in renal sympathetic nerve activity will lead to which
combination of changes: Ans: increased renal renin release and a fall in
renal plasma flow
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- alpha adrenergic fibers stimulate renal arterioles and small arteries to
vasoconstrict, lowering renal plasma flow. beta adrenergic nerve fibers
stimulate renin release from the granular cells in afferent arteriole
an increase in antiduretic hormone (ADH) release will occur when: Ans:
plasma osmolality increases by 2% - when plasma osm increases by
greater than 1% above normal, ADH is released
a patient with nephrogenic diabetes insipidus is most likely to present
with which combination of plasma and urine osmolality Ans: high plasma
osmolality, low urine osmolality
- nephrogenic diabetes insipidus means the collecting duct cannot
reaborb water, so urine is dilute and plasma osm increases due to renal
water loss
ADH (Antidiuretic hormone) stimulates the reabsorption of ___ and ___
in the kidney collecting ducts of a normal individual. Choose 1 best
answer: Ans: water & urea
urine concentration will increase when the following events occur: Ans:
blood volume falls by 15%
- when blood volume falls by >10% ADH is released in large quanitities.
water is retained and urine concentration increases
the primary regulation of renal potassium (K) excretion occurs in which
segment? Ans: collecting duct. K is reabsorbed in proximal tubule and
TALH and usually secreted in the collecting duct (from the principal cells)
unless the body needs to retain K in which case further reabsorption can
occur in the collecting duct (via intercalated cells type A)
the kidney plays a role in maintaining calcium and phosphate balance in
the body. choose 1 best answer: Ans: activation of Vitamin D to calcitriol
occurs in the kidney and promotes urinary phosphate reabsorption. the
terminal hydroxylation step which activates Vitamin D to 1-25 dihydroxy
vitamin D (Calcitriol) takes place in the kidney, and calcitriol decreases
tubular phosphate excretion