Week 10 - Micturition

Micturition

the action of urination

What is the somatic bladder nerve?

pudendal nerve

What is the sympathetic bladder nerve?

hypogastric nerves

What is the parasympathetic baldder nerve?

pelvic nerves

What spinal nerves make te pudendal nerve?

S2-S4

What spinal nerves make the hypogastric nerve?

L1-L3

What spinal nerves make the pelvic nerves?

S2-S4

What structure in the bladder does the pudendal nerve innervate?

external uretheral sphincter

What structure in the bladder does the hypogastric and pelvic nerve innervate?

bladder wall and internal sphincter

Effect of parasympathetic supply on the detrusor muscle

causes it to contract

Effect of parasympathetic supply on the internal sphincter

causes relaxation

Effect of parasympathetic supply on micturition

facilitates emptying

Effect of sympathetic supply on the detrusor muscle

causes relaxation

Effect of sympathetic supply on the internal sphincter

causes contraction

Through what receptor does the sympathetic nerves affect the detrusor muscle?

β-3

Through what receptor does the sympathetic nerves affect the internal sphincter?

α-1

through what receptor does the somatic nerves control the external sphincter?

nicotinic

through what receptor does the parasympathetic control the detrusor muscle?

M-3

What higher centers stimulate micturition?

pons and posterior hypothalamus

What higher centers inhibit micturition

Cerebral cortex and midbrain

What causes atonic bladder?

sensory nerves from the bladder are damaged

What is the state of micturition reflex in an atonic reflex?

there is none

What happens to micturition during an atonic bladder?

urine overflows from bladder and a few drops leaves the urethra

What causes automatic bladder?

spinal cord damage above the sacral region

What is the state of the micturition in an automatic bladder?

sacral micturition is still intact

Renal clearance

the rate to which substances are removed from the plasma

What happens to substances that have a low renal clearance?

they aren’t removed at all

What happens to substances that have a high renal clearance?

they are completely removed

Is inulin reabsorbed or secreted?

It’s neither

What is the ideal glomerular marker?

inulin

What substance slightly overestimates the GFR?

creatinine

What is the best substance to measure renal plasma flow?

para-aminohippuric acid