Renal Assessemt and Micturation

Question 1

what do plasma clearance tests measure?

Answer 1

renal function: the ability of the kidney to clear the plasma of various substances (the volume of plasma cleared not quantity of removed substance)

Question 2

describe testing insulin clearance

Answer 2

> poly fructose
iv loading of insulin
allow time to equilibrate
sample plasma and urine simultaneously

Question 3

what is the equation for the plasma clearance of X?

Answer 3

([urine X] MULTIPLIED BY the urine flow rate)/plasma concentration

Question 4

why can insulin be used to measure GFR?

Answer 4

> freely filtered
> not secreted
> not reabsorbed
> not metabolised by the kidney
> doesn't interfere with normal renal function

Question 5

true or flase:

GFR declines 1 ml/min/year after 30

Answer 5

true

Question 6

what is used now to measure GFR instead of insulin?

Answer 6

51Cr-ADTA

Question 7

what is creatinine a breakdown product of?

Answer 7

muscle creatine

Question 8

true or false

plasma creatinine and GFR have a linear relationship

Answer 8

false

the GFR can half before there is an elevation in plasma creatinine

Question 9

what factors affect serum creatinine?

Answer 9

> muscle mass
drugs (ketoacidosis)
dietary intake (supplements and vegetarians)

Question 10

what does para-amino-hippuric acid measure?

Answer 10

all the plasma flowing through the kidney at one time

Question 11

why can PAH be used to measure renal plasma flow?

Answer 11

it is freely filtered at the glomerulus and then secreted unto the tubule so >90% is cleared from the plasma in one transit

Question 12

contraction of what muscle empties the bladder?

Answer 12

detrouser muscle

Question 13

what epithelium lines the bladder?

Answer 13

transitional

Question 14

true or false

urethral obstruction will lead to bilateral renal problems

Answer 14

true

Question 15

what is the parasympathetic effect on micturition?

Answer 15

> increases activity
increasing contraction of the detrusor muscle
increasing pressure within the bladder

Question 16

what is the sympathetic innervation of micturition?

Answer 16

(hypogastric nerve) inhibits bladder contraction and closes the internal sphincter

Question 17

describe somatic motor neuron effects on micturition

Answer 17

innervates skeletal muscle of the external urethral sphincter keeping it closed

Question 18

describe the effect of a full bladder stretching the receptor afferent in the bladder wall

Answer 18

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

Question 19

if you are delaying micturition do you excite or inhibit sympathetic and somatic motor neurons?

Answer 19

excite

Question 20

if you are initiating micturition do you excite or inhibit parasympathetic neurons?

Answer 20

excite

Question 21

what is one of the initial events in voluntary urination?

Answer 21

relaxation of the pelvic floor muscles (causing a tug on the detrusor muscle initiating contraction)

Question 22

what muscles can be contracted voluntarily preventing urine flow down the urethra?

Answer 22

> perineal muscle

> external sphincter

Question 23

how is urine in the male urethra expelled?

Answer 23

contractions of the bulbocavernous muscle

Question 24

what can cause abnormalities in micturition?

Answer 24

> afferent nerve interruption
afferent and efferent interruption
interruption of facilatory and inhibitory descending pathways from the brain