Micturition Reflex

Question 1

What is the definition of the micturition reflex?

Answer 1

The micturition reflex is the neural mechanism by which the urinary bladder empties.

Question 2

What role does the detrusor muscle play in micturition?

Answer 2

The detrusor muscle contracts to expel urine from the bladder during micturition.

Question 3

How is the internal urethral sphincter involved in the micturition reflex?

Answer 3

The internal urethral sphincter relaxes to allow urine to pass from the bladder into the urethra.

Question 4

What is the function of the external urethral sphincter during micturition?

Answer 4

The external urethral sphincter provides voluntary control over the initiation of micturition.

Question 5

Which part of the nervous system controls the micturition reflex?

Answer 5

The autonomic nervous system controls the micturition reflex.

Question 6

How do stretch receptors in the bladder wall contribute to micturition?

Answer 6

Stretch receptors in the bladder wall detect filling and send signals to the spinal cord and brain.

Question 7

What role does the pontine micturition center play in the micturition reflex?

Answer 7

The pontine micturition center coordinates the activities of the bladder and urethral sphincters.

Question 8

How is the parasympathetic nervous system involved in the micturition reflex?

Answer 8

The parasympathetic nervous system stimulates bladder contraction and sphincter relaxation.

Question 9

What is the function of the sympathetic nervous system in micturition?

Answer 9

The sympathetic nervous system inhibits bladder contraction and keeps the internal urethral sphincter closed.

Question 10

How does voluntary control of micturition occur?

Answer 10

Voluntary control of micturition occurs through the external urethral sphincter, controlled by the somatic nervous system.

Question 11

What is the sequence of events in the initiation of the micturition reflex?

Answer 11

The sequence begins with bladder filling, activation of stretch receptors, signals to the brain, and coordinated muscle contractions and sphincter relaxations.

Question 12

How does the bladder signal the brain that it is full?

Answer 12

The bladder signals the brain via sensory neurons that respond to stretch as the bladder fills.

Question 13

What neurotransmitters are involved in the micturition reflex?

Answer 13

Acetylcholine is a key neurotransmitter in the parasympathetic activation of the detrusor muscle.

Question 14

How does the process of micturition differ between infants and adults?

Answer 14

Infants have an involuntary micturition reflex, while adults develop voluntary control over time.

Question 15

What role do higher brain centers play in the control of micturition?

Answer 15

Higher brain centers in the frontal lobe can facilitate or inhibit the micturition reflex.

Question 16

How does the micturition reflex prevent involuntary urination?

Answer 16

The micturition reflex prevents involuntary urination by maintaining the internal and external sphincters closed until appropriate.

Question 17

What is the effect of spinal cord injuries on the micturition reflex?

Answer 17

Spinal cord injuries can disrupt the coordination and control of the micturition reflex.

Question 18

How does aging affect the micturition reflex?

Answer 18

Aging can lead to decreased bladder capacity, increased frequency, and potential incontinence.

Question 19

What are common disorders associated with the micturition reflex?

Answer 19

Common disorders include overactive bladder, urinary retention, and incontinence.

Question 20

How does the detrusor muscle respond to acetylcholine?

Answer 20

Acetylcholine stimulates the detrusor muscle to contract during micturition.

Question 21

What role does the pelvic nerve play in the micturition reflex?

Answer 21

The pelvic nerve carries parasympathetic signals to the bladder, initiating contraction.

Question 22

How do the hypogastric nerves influence micturition?

Answer 22

Hypogastric nerves carry sympathetic signals that inhibit bladder contraction and maintain continence.

Question 23

What is the function of the pudendal nerve in micturition?

Answer 23

The pudendal nerve controls the external urethral sphincter, allowing voluntary control of urination.

Question 24

How does the micturition reflex change with a full bladder versus a partially full bladder?

Answer 24

A full bladder triggers a stronger and more urgent micturition reflex compared to a partially full bladder.

Question 25

What is the effect of anticholinergic drugs on micturition?

Answer 25

Anticholinergic drugs inhibit the action of acetylcholine, reducing bladder contractions and increasing storage capacity.

Question 26

How does the voluntary relaxation of the external urethral sphincter occur?

Answer 26

Voluntary relaxation of the external urethral sphincter is achieved by inhibiting motor neurons that innervate it.

Question 27

What are the phases of the micturition cycle?

Answer 27

The phases of the micturition cycle include the storage phase and the voiding phase.

Question 28

How does urinary incontinence relate to the micturition reflex?

Answer 28

Urinary incontinence occurs when the micturition reflex fails to properly coordinate sphincter and bladder activity.

Question 29

What is the role of mechanoreceptors in the bladder wall?

Answer 29

Mechanoreceptors in the bladder wall respond to stretching and initiate the micturition reflex.

Question 30

How does the voiding phase of micturition occur?

Answer 30

The voiding phase occurs when the detrusor muscle contracts, and both the internal and external urethral sphincters relax, allowing urine to be expelled.