Renal Assessemt and Micturation Flashcards
what do plasma clearance tests measure?
renal function: the ability of the kidney to clear the plasma of various substances (the volume of plasma cleared not quantity of removed substance)
describe testing insulin clearance
> poly fructose
iv loading of insulin
allow time to equilibrate
sample plasma and urine simultaneously
what is the equation for the plasma clearance of X?
([urine X] MULTIPLIED BY the urine flow rate)/plasma concentration
why can insulin be used to measure GFR?
> freely filtered > not secreted > not reabsorbed > not metabolised by the kidney > doesn't interfere with normal renal function
true or flase:
GFR declines 1 ml/min/year after 30
true
what is used now to measure GFR instead of insulin?
51Cr-ADTA
what is creatinine a breakdown product of?
muscle creatine
true or false
plasma creatinine and GFR have a linear relationship
false
the GFR can half before there is an elevation in plasma creatinine
what factors affect serum creatinine?
> muscle mass
drugs (ketoacidosis)
dietary intake (supplements and vegetarians)
what does para-amino-hippuric acid measure?
all the plasma flowing through the kidney at one time
why can PAH be used to measure renal plasma flow?
it is freely filtered at the glomerulus and then secreted unto the tubule so >90% is cleared from the plasma in one transit
contraction of what muscle empties the bladder?
detrouser muscle
what epithelium lines the bladder?
transitional
true or false
urethral obstruction will lead to bilateral renal problems
true
what is the parasympathetic effect on micturition?
> increases activity
increasing contraction of the detrusor muscle
increasing pressure within the bladder
what is the sympathetic innervation of micturition?
(hypogastric nerve) inhibits bladder contraction and closes the internal sphincter
describe somatic motor neuron effects on micturition
innervates skeletal muscle of the external urethral sphincter keeping it closed
describe the effect of a full bladder stretching the receptor afferent in the bladder wall
there is - through interneurons:
> excitation of parasympathetic outflow
> inhibition of sympathetic outflow
> inhibition of somatic motor neurons to the external sphincter
> activation of pathways tot the sensory cortex
if you are delaying micturition do you excite or inhibit sympathetic and somatic motor neurons?
excite
if you are initiating micturition do you excite or inhibit parasympathetic neurons?
excite
what is one of the initial events in voluntary urination?
relaxation of the pelvic floor muscles (causing a tug on the detrusor muscle initiating contraction)
what muscles can be contracted voluntarily preventing urine flow down the urethra?
> perineal muscle
> external sphincter
how is urine in the male urethra expelled?
contractions of the bulbocavernous muscle
what can cause abnormalities in micturition?
> afferent nerve interruption
afferent and efferent interruption
interruption of facilatory and inhibitory descending pathways from the brain
