PHS3300 Renal pathophysiology Exam
Questions With Correct Answers
Renal blood flow: how much blood does the kidney receive per minute?
what is this in comparison with the cardiac output? - answer✔both kidneys receive 1200 ml or
1.2 L per minute.
25% of CO - 10% of blood travels to medulla (collecting duct, reabsorption, secretion,
excretion), where 90% of blood travels to the cortex (glomerulus --> filtration unit)
How much blood that enters the kidney is absorbed back into the body/ how much ends up
excreted in urine? - answer✔99% (180L filtred/24 hours) absorbed.
1% (1-1.8 L of urine) excreted
describe the structure of a kidney including how many glomeruli are present, the inner section
of the kidney, the outer most section of the kidney, and the arterioles that blood travels
through to get into a glomerulus + the ones it uses to get out - answer✔1 millions glomeruli in
each kidney .medulla is inner most point of kidney. cortex is outer most part.
Blood comes in through afferent arteriole to glomerulus. It is then filtered through many
capillaires (made of epithelial cells where filtration occurs. Now, blood exits through efferent
arterioles. Urine is eventually produced (this contains no albumin (blood protein). Should
contain no proteins... if we are loosing proteins, we can be at risk of edema.
what can we use to test kidney function? - answer✔calculate the glomerular filtration rate
(GFR)
GFR (glomerular filtration rate)
what is it and what units is it measured in? - answer✔Rate at which plasma moves through
glomerular capillaries
ml/min
the volume of fluid filtered from the glomerular capillaries into Bowman's capsule per unit
time. Clinically, GFR is measured to determine renal function.
do males and females have a different GFR? what accounts for the difference?
when do children have adult proportions? - answer✔•Females 85-125 ml/min, Males 97-140
ml/min for two kidneys - WHY is there a difference? Males have larger kidneys.
by 2 years of age
what is the driving force for GFR? - answer✔Glomerular capillary hydrostatic pressure (postive
force). Every time our heart beats, it pushes blood through renal arteries and push blood into
afferent arterioles. There is a drop in blood pressure as the diameter of each vessel gets smaller
towards the kidney. .
how would plasma concentration levels of creatine reflect the GFR of a patient suffering from
chronic kidney disease (CKD?) - answer✔•If GFR decreases (due to CKD), then excretion <
production for creatinine, so plasma [Cr] increases.
New steady-state is reached where excretion is almost = to production.
Plasma [Cr] is now increased
does plasma levels of creatinine concentration reflect GFR in steady state conditions? name 5
reasons why creatinine reflects a GFR in steady state conditions. - answer✔yes.
•Creatinine is produced by skeletal muscle at a constant rate
•
•Creatinine is excreted mainly by filtration I.e. GFR X plasma [Cr]
•
•Renal excretion = Muscle production
•
•Therefore, Plasma [Cr] is constant under normal circumstances
•
•Range of normal plasma [Cr] is 50-110 µmol/L - depends on factors like muscle mass.
Johnny is suffering from type 2 diabetes, in which is GFR has been elevated. What do you
expect to occur to his creatinine levels?
How about if Johnny had kidney disease? - answer✔they should decrease due to filtration rate
being elevated... more creatinine is being excreted in the urine.
If kidney disease, creatinine concentration goes up since it isn't being excreted.
describe the 4 characteristics of a substance that must apply in order for it to be used to
measure GFR - answer✔must be freely filtered
must not be reabsorbed or secreted
must not alter GFR: it can't be a factor that would change GFR - like a hormone for example.
must not be synthesized or catabolized by the kidney: We don't want it to be made in the
kidney or broken down in the kidney
substances used to measure GFR:
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