Renal function Flashcards
What are the physiological functions of the kidneys
regulate extracellular fluid solute concentrations
regulate plasma electrolye concentrations
regulate acid-base balance
regulate extracellular fluid volume, arterial blood pressure
eliminate metabolic wastes, foreign chemicals
What hormones do kidneys produce
erythropoietin, vit D and renin
what compunds are synthesized in kidneys
ammonia, PGs, kinins and glucose
What other body systems are the kidneys intergrated with
GI, endo, CNS, ANS, CNS, resp, CV, liver
what are some of the key sequlae to kidney failure
anemia due to loss of forming new RBC
osteoporosis due to loss of forming bone
disregulation of Ca and phosphates
what is another name for interlobular aa
cortical radial arteries
what portion of CO does the renal blood receive
20%
are the glomerular capiilaries high or low P and why?
high pressure to cause filtration of blood
are the peritubular capillaries high or low P and why?
low because want to reabsorb
how are the P in the capillaries altered in renal system
changes in afferent and efferent arteriolar resistance
What are the two types of nephrons
Juxtamedullary which go deeper to renal papilla
Superficial cortical
characteristics of superficial cortical nephrons
short loops of henle
surrounded by particular capillaries
characteristics of juxtamedullary nephrons
long loops of henle
efferent arterioles are covered by vasa recta (specialized peritubular capillaries)
mainly functions for urine concentration
describe the renal microcirculation path
afferent arteriole
glomerular capillaries
efferent arteriole
peritubular capillaries
describe venouse drainage of nephrons
interlobular v
arcuate v
interlobar v
renal v
what are the advantages of high renal blood flow
high filtration rate
how does renal fraction change during exercise
it decreases because shunting to skel muscle and want to retain H2O
What regions of the kidneys receive more blood
the cortical nephrons
how does blood perfusionc hang with aging
decreases because we lose the number of functioning nephrons
where do sympathtetic neurons synapse in kidneys
smooth muscle to cause arteriolar constriction to protect from high BP
granular cells to cause renin secretion in afferent arterioles
what is the function of renin
to cause retention of Na and H2O
what are the net effects of sympathetic stimulation
decrease renal blood flow and diver renal fraction to vital organs
what is glomerular filtration
filtration of plasma from glomerular capillaries into Bowmans capsule
what is tubular reabsorption
transferal of substances from tubular lumen to pertibular capillaries
what is tubular secretion
trasnferal of substances from peritubular capillaries to tubular lumen, like waste such as urea
what is excretion
voiding substances in the urine
how can we calculate urinary excretion
amount filtered-amount reabsorbed+amount secreted
how can we measure tubular reabsorption
glomerular filtration- urinary excretion
what is glomerular filtration rate
volume of plasma filtered per unit time
the filtration rate of a substance is calculated how
GFR x plasma concetration of substance
how do we calculate urinary excretion rate
product of urine flow rate x concentration of substance in the urine
if excretion is less than filtration what does that indicate
if excretion is more than filtration what does that indicate
when excretion filtration- net secretion occurred
what is the definition of clearance
the volume of plasma from which a substance is completely removed by kidneys in a given time period
what are the units of clearance
volume/time
ml/min
L/hr
Is clearance the same for all substances
no
how do we calculate clearance
concentration of X in urine * urine volume
___________________________________
concentration of x in plasma
Under what conditions can GFR be estimated from clearance
compound can freely filter thorugh glomerulus, cannot be secreted, reabsorbed, produced nor degraded by kidneys
What molecules do we use to calculate GFR
inulin because it is not secreted reabsorbed or metabolized
Creatinine- not perfect and used for long term
describe how the BUN creatinine ration works
because creatinine is unaffected by hydration status it acts as a constant.
so we can tell when urea is too high or low.. where the problem may be in kidney problems
Cystatin C
describe what a BUN/C ratio above 20 indicates
prerenal problem
BUN reabsorption is increased
reduced perfusion due to hypovolemia
What is a normal BUN/C level
10-20/1
what does a BUN/C ratio below 10 suggest
intrarenal problem
renal damage causing reduced reabsorption of BUN
what are the advantages of using Cystatin C to measure GFR rather than creatinine
no affected by muscle mass, age or gender
What measurement of clearance can give an estimate of renal plasma flow
Para-amino hippuric acid
What is the filtration fraction
part of renal plasma flow that is filtered/diverted into tubule
what is the calculation for filtration fraction
FF= GFR/RPF
the kidney is the only place that can rid the body of what acids
sulfuric acid and phosphoric acid
what stimulates the kidneys to secrete erythropoeitin
hypoxia
where is the macula densa
at the end of the ascending limb
what type of reflex is micturition
autonomic spinal cord reflex
how can the trigone be distinguished by the rest of the bladder
its mucosa is smooth unlike the extensive foldings of the rest of the bladder
which sphincter of the bladder is voluntary
the external
what spinal cords innervate bladder
S2S3 through sacral plexus, sensory and motor
what type of fibers innervate detrusor mm
PANS
what nerves innervate the external sphincter
skel mm nerves, pudendal
L2 also but not much
a person with vesicoureteral reflex suffers the condition because
their ureters don’t quite protrude as far into the bladder so the ureter is not completely blocked when bladder contracts
what does the ureterorenal reflex prevent
preventing excessive flow of fluid into a blocked ureter
what substances usually are filtered but then completely reabsorbed
amino acids and glucose
what substances are filtered in glomercular capillaries and completely secreted in peritubular capillaries
organic acids and bases
what molecules in plasma do not get filtered
plasma Ca and plasma FA because are bound to protein
