Micturition

Question 1

What is micturition?

Answer 1

Urination

Question 2

Name the 4 steps of the micturition cycle.

Answer 2

1. Storage
2. Switch from storage to voiding
3. Voiding
4. Switch from voiding to storage

Question 3

Which stage of micturition are we in most of the time?

Answer 3

Storage - 98% of time

Question 4

Where is the detrusor muscle?

Answer 4

Bladder wall

Question 5

What type of muscle is detrusor muscle?

Answer 5

Smooth

Question 6

There are two urethral sphincters, name them.

Answer 6

Internal urethral sphincter

External urethral sphincter

Question 7

Where is the internal urethral sphincter?

Answer 7

At inferior end of bladder

It is a continuation of the detrusor muscle

Question 8

Where is the external urethral sphincter?

Answer 8

In females: part-way along the urethra below bladder neck

In males: inferior to prostate

Question 9

What type of muscle is the internal urethral sphincter?

Answer 9

Smooth

Question 10

What type of muscle is the external urethral sphincter?

Answer 10

Skeletal

Question 11

What control is the internal urethral sphincter under?

Answer 11

Smooth muscle

So it is under involuntary and autonomic control

Question 12

What control is the external urethral sphincter under?

Answer 12

Skeletal muscle

So voluntary

Question 13

What is the somatic nerve that controls the external sphincter?

Answer 13

Deep perineal branch of pudendal nerve

Question 14

During storage, what are the muscles doing?

Answer 14

Detrusor muscle relaxed

Urethral sphincter contracted

Question 15

During the switch from storing to voiding, what do the muscles do?

Answer 15

Urethral sphincter relaxes

Detrusor muscle contracts

Question 16

What enables voiding to occur?

Answer 16

Detrusor muscle contraction is sufficient to cause bladder emptying

Question 17

During the switch from voiding to storage, what do the muscles do?

Answer 17

Urethral sphincter contracts

Detrusor muscle relaxes

Question 18

What parts of the brain control micturition?

Answer 18

The frontal cortex
Septal region
Hypothalamus
Pontine micturition centre

Question 19

What type of nerves are involved in micturition?

Answer 19

Sympathetic
Parasympathetic
Somatic (voluntary)

Question 20

Where do the sympathetic nerves that play a part in micturition originate from? (from the spinal cord)

Answer 20

T10-L2

Question 21

Where do the parasympathetic nerves that play a part in micturition originate from? (from the spinal cord)

Answer 21

S2-S4

Question 22

What effect do sympathetic nerves have on micturition?

Answer 22

Urethral contraction

Inhibition of detrusor contraction

Question 23

What effect do parasympathetic nerves have on micturition?

Answer 23

Internal urethral relaxation

Detrusor contraction

Question 24

What effect do somatic nerves have on micturition?

Answer 24

Relaxation of external urethral sphincter

Question 25

Which nervous system(s) enables micturition?

Answer 25

Parasympathetic

Somatic

Question 26

Which nervous systems(s) inhibit micturition?

Answer 26

Sympathetic