The Urinary Bladder

Question 1

What facilitates movement of urine into the bladder

Answer 1

Peristaltic contractions of the walls of the uereter

Question 2

capacity of urinary bladder

Answer 2

600-800 mL

Question 3

what is the urinary bladder

Answer 3

a muscular sac

Question 4

What is the urinary bladder like when empty

Answer 4

collapsed and relaxed

Question 5

Detrusor

Answer 5

main muscle of the bladder wall

composed of 3 layers of smooth muscle fibres, arranged differently in each layer (spiral, longitudinal, circular)

Question 6

How is stored urine moved to the exterior

Answer 6

via urethra

Question 7

sphincters at urethral opening

Answer 7

2 muscular rings that control the opening

Question 8

Internal sphincter

Answer 8

Involuntary

smooth muscle- normally closed (passive contraction)

Question 9

External sphincter

Answer 9

voluntary

skeletal muscle- normally closed (tonic contraction)

Question 10

trigone muscle

Answer 10

bladder’s stretch receptors

Question 11

What does neural regulation of bladder function involve (control of Micturition)

Answer 11

PNS and CNS

Question 12

Involuntary spinal micturition reflex arc (MR)

Answer 12

present from birth

1. stretch receptors in wall of urinary bladder
2. afferent sensory nerve fibres convey impulses to the spinal cord
3. Efferent PS nerve fibres convey impulses to detrusor and internal sphincter

Question 13

Voluntary nervous control exercised by the CNS (+ and -)

Answer 13

cortex, cerebellum and micturition centre located in the pons (PMC- pontine micturition centre)
Develops in early childhood, full control at age 3-5

Question 14

micturition

Answer 14

passing/ voiding of urine

ie peeing

Question 15

neural pathways controlling micturition

Answer 15

1. Urine fills bladder and stretches wall
2. Stretch receptors send a signal via sensory afferent fibres to sacral portion of spinal cord
3. Parasympathetic efferent fibres stimulate detrusor muscle to contract and internal urethral sphincter to relax, causing micturition
4. Interneurons in spinal cord communicate the ‘full bladder’ signal to micturition center in the pons
5. Cerebral cortex facilitates micturition by allowing external urethral sphincter to relax, urine voided

Question 16

contraction of detrusor muscle

Answer 16

squeezes on the urine in the bladder lumen to produce urination

Question 17

What happens when the bladder is filling

Answer 17

parasympathetic input to detrusor muscle is minimal, so the muscle is relaxed. When the detrusor muscle is relaxed, the internal sphincter is passively closed due to how the layers of muscle are arranged.
Also there is strong sympathetic input to the internal urethral sphincter and strong input by somatic motor neurones to the external urethral sphincter.
Hence detrusor relaxed and both sphincters shut

Question 18

detrusor type of innervation

Answer 18

parasympathetic (causes contraction)

Question 19

internal sphincter type

Answer 19

sympathetic (causes contraction)

Question 20

External sphincter type

Answer 20

Somatic motor (causes contraction)

Question 21

During filling which muscles stimulated

Answer 21

detrusor inhibited

internal and external sphincter stimulated

Question 22

During micurition which muscles stimulated

Answer 22

only detrusor

Question 23

Incontinence

Answer 23

Involuntary release of urine

Question 24

Male urethra surrounded by

Answer 24

penis

Question 25

sphincters play a role in

Answer 25

holding urine in bladder

Question 26

What is found between sphincters in males

Answer 26

prostate gland-activates sperm

Question 27

Female system

Answer 27

doesn’t have internal sphincter
shorter urethra
More likely change of UTI

Question 28

where is micturition centre

Answer 28

pons

Question 29

stretching of bladder causes

Answer 29

incr firing of pelvic nerve- fast signals to spinal cord, then to micturition centre. Sends impulses to cause contraction of detrusor