6. Micturition

Question 1

The upper urinary tract has the kidney and ureter which has what type of muscle that can do what?

Answer 1

Has smooth muscle that can contract and relax (perastalsis) via sympathetic and parasympathetic control
(also senses pain)

Question 2

The lower urinary tract consists of the bladder and urethra which has smooth much which is?
What about the external sphincter?

Answer 2

involuntary

the external urethral spinchter has skeletal muscle which is voluntary.

Question 3

What does the trigone do (mesoderm)?

Answer 3

Sense when the bladder is full and sends a signal to the brain to pee

Question 4

Blockade of the ureteral out flow via a kidney stone would cause pain in the ureter to go via sympathetic to constrict renal arterioles to decrease urine output. What are the other 3 things commonly seen with blockage?

Answer 4

1. increase in hydrostatic pressure
2. ureteral dilation
3. continued block which increases pressure leading to kidney swelling and hydronephrosis

Question 5

What are the 4 anatomical constriction points where the ureter can be compressed and where on the ureter?

Answer 5

1. ureteropelvic junction (UTJ) at the hilum of kidney
2. Testicular/ovarian artery/vein at upper 1/3 ureter
3. External iliac A/V at lower 1/3 ureter
4. Bladder wall at entrance into bladder

Question 6

What occurs in the vesicoureteral reflex and what does it increase the risk of?

Answer 6

is when urine travels back up the ureter which could lead to increased risk of pyelonephritis (kidney infection) due to urine being exposed to external sphincter and then being brought back into the body

Question 7

When there is a stretch due to intravesicle pressure it signals sensory nerve fibers which run with pelvic splanchnic nerves and hypogastric plexus. Where does the sensory information come from?

Answer 7

S2-S4 which is the sacral mictruition center

Question 8

Bladder fullness is sent via alpha/delta myelinated fibers while bladder pain (abnormal) is sent via?

Answer 8

c unmyelinated fibers (always present only sense pain when there is some)

Question 9

What NT and receptor is related to S2-S4 pelvic splanchnic N traveling to detrusor M causing contraction and internal sphincter muscle causing relaxation?

Answer 9

Parasympathetic NS (involuntary)
NT: Ach
R: M3 muscarinic AchR
PEE TIME

Question 10

What NT and receptor is related to L2 hypogastric N going to relax the detrusor muscle and contract the internal sphincter muscle?

Answer 10

Sympathetic (involuntary)
NT: NE
R: Alpha 1 in ureter, B2/3 in detrusor

Question 11

What NT and receptor is related to S2-S4 pudendal N which causes contraction at the external ureter sphincter?

Answer 11

Somatic voluntary
NT: Ach
R: NicotinicAchR

Question 12

What reflex only goes to the spinal cord (no brain) and is activated by bladder filling, resulting in detrusor muscle relaxation via sympathetic and external sphincter contraction via somatic?

Answer 12

Bladder reflex (guarding)

*quick

Question 13

What relfex goes to the brain and is activated by a full bladder, whose afferent neurons trasmit to SC and then to brain which stimulates parasympathic outflow and inhibits symp/somatic to result in detrusor contraction (parasymp) and external spincter relaxation (somatic)

Answer 13

The voiding (PEE TIME) reflex

Question 14

What are the two main things the cerebral cortex does?

Answer 14

interprets sensation/ fullness

can partially inhibit mictruition reflex

Question 15

The midbrain also known as periaqueductal gray (PAG) receives afferent bladder signals and what other two things?

Answer 15

it the primary excitation input to PMC

the cortex/higher brain centers can supress or stimulate input of PAG to the PMC

Question 16

The pons does the most of the work, this is where the pontine mictruition center is (PMC), AKA barringtons nucleus. What are the 3 main things it does?

Answer 16

1. receives signals from PAG and higher (cortex) brain centers
2. activates external sphincter to relax and sacral parasumpathetic outflow to contract (mictruition!)
3. controls/coordinates S2-S4 sacral mictruition

Question 17

What is the difference between adults and infants regarding mictruition?

Answer 17

Adults have coordinated detrusor and sphincter muscles but have voluntary control over start/stop of urination

Children have coordination of detrusor and spinchter muscles but have involuntary control over the start/stop if urine (will also void at lower volumes)

Question 18

In parapalegics, or an injury above S2-S4, what will happen?

Answer 18

voiding will occur at lower volumes.
involuntary starting and stoping
detrusor and sphincter do not work together (uncordinated) (bladder contracts but so does sphincter)

Question 19

What time of pain is associated with a kidney stone?

Answer 19

Paroxysmal pain (it comes and goes) because the ureter is not always contracting

Question 20

What could be use to inhibit or lessen ureter contraction to pass a kidney?

Answer 20

an alpha1 antagonist (causes relaxation)

Question 21

An EMG cannot detect whether a muscle is voluntary or involuntary but it can detect what?

Answer 21

coordination between muscles (detrustor and sphincter)

Question 22

If someone was given a acetylcholinesterase inhibitor, what would most likely happen?

Answer 22

Remember the only receptor that is involuntary is via parasympathetics. So the M3 receptors would increase in activity d/t increase NT, causing an increase in detrusor contraction and increase in sphincter relaxation

Question 23

What is another antomical area that can compress the urethra in males compared to females?

Answer 23

the prostate can cause impingment of the urethra, which is also longer in males