Micturition Reflex Flashcards
What is the definition of the micturition reflex?
The micturition reflex is the neural mechanism by which the urinary bladder empties.
What role does the detrusor muscle play in micturition?
The detrusor muscle contracts to expel urine from the bladder during micturition.
How is the internal urethral sphincter involved in the micturition reflex?
The internal urethral sphincter relaxes to allow urine to pass from the bladder into the urethra.
What is the function of the external urethral sphincter during micturition?
The external urethral sphincter provides voluntary control over the initiation of micturition.
Which part of the nervous system controls the micturition reflex?
The autonomic nervous system controls the micturition reflex.
How do stretch receptors in the bladder wall contribute to micturition?
Stretch receptors in the bladder wall detect filling and send signals to the spinal cord and brain.
What role does the pontine micturition center play in the micturition reflex?
The pontine micturition center coordinates the activities of the bladder and urethral sphincters.
How is the parasympathetic nervous system involved in the micturition reflex?
The parasympathetic nervous system stimulates bladder contraction and sphincter relaxation.
What is the function of the sympathetic nervous system in micturition?
The sympathetic nervous system inhibits bladder contraction and keeps the internal urethral sphincter closed.
How does voluntary control of micturition occur?
Voluntary control of micturition occurs through the external urethral sphincter, controlled by the somatic nervous system.
What is the sequence of events in the initiation of the micturition reflex?
The sequence begins with bladder filling, activation of stretch receptors, signals to the brain, and coordinated muscle contractions and sphincter relaxations.
How does the bladder signal the brain that it is full?
The bladder signals the brain via sensory neurons that respond to stretch as the bladder fills.
What neurotransmitters are involved in the micturition reflex?
Acetylcholine is a key neurotransmitter in the parasympathetic activation of the detrusor muscle.
How does the process of micturition differ between infants and adults?
Infants have an involuntary micturition reflex, while adults develop voluntary control over time.
What role do higher brain centers play in the control of micturition?
Higher brain centers in the frontal lobe can facilitate or inhibit the micturition reflex.
How does the micturition reflex prevent involuntary urination?
The micturition reflex prevents involuntary urination by maintaining the internal and external sphincters closed until appropriate.
What is the effect of spinal cord injuries on the micturition reflex?
Spinal cord injuries can disrupt the coordination and control of the micturition reflex.
How does aging affect the micturition reflex?
Aging can lead to decreased bladder capacity, increased frequency, and potential incontinence.
What are common disorders associated with the micturition reflex?
Common disorders include overactive bladder, urinary retention, and incontinence.
How does the detrusor muscle respond to acetylcholine?
Acetylcholine stimulates the detrusor muscle to contract during micturition.
What role does the pelvic nerve play in the micturition reflex?
The pelvic nerve carries parasympathetic signals to the bladder, initiating contraction.
How do the hypogastric nerves influence micturition?
Hypogastric nerves carry sympathetic signals that inhibit bladder contraction and maintain continence.
What is the function of the pudendal nerve in micturition?
The pudendal nerve controls the external urethral sphincter, allowing voluntary control of urination.
How does the micturition reflex change with a full bladder versus a partially full bladder?
A full bladder triggers a stronger and more urgent micturition reflex compared to a partially full bladder.
What is the effect of anticholinergic drugs on micturition?
Anticholinergic drugs inhibit the action of acetylcholine, reducing bladder contractions and increasing storage capacity.
How does the voluntary relaxation of the external urethral sphincter occur?
Voluntary relaxation of the external urethral sphincter is achieved by inhibiting motor neurons that innervate it.
What are the phases of the micturition cycle?
The phases of the micturition cycle include the storage phase and the voiding phase.
How does urinary incontinence relate to the micturition reflex?
Urinary incontinence occurs when the micturition reflex fails to properly coordinate sphincter and bladder activity.
What is the role of mechanoreceptors in the bladder wall?
Mechanoreceptors in the bladder wall respond to stretching and initiate the micturition reflex.
How does the voiding phase of micturition occur?
The voiding phase occurs when the detrusor muscle contracts, and both the internal and external urethral sphincters relax, allowing urine to be expelled.
