Kidney Summaries

What type of muscle is found in the bladder wall?

Smooth muscle (detrusor muscle).

What type of muscle forms the internal sphincter of the bladder?

Smooth muscle (involuntary control).

What type of muscle forms the external sphincter of the bladder?

Skeletal muscle (voluntary control).

What happens to the detrusor muscle during bladder filling?

It remains relaxed under sympathetic control.

What happens to the bladder neck during bladder filling?

It remains closed by the internal sphincter.

What controls the external sphincter during bladder filling?

Pudendal nerve maintains contraction (voluntary skeletal muscle).

What initiates the micturition reflex?

Stretch receptors in the bladder wall fire as the bladder fills.

What nervous system activates during bladder emptying (voiding)?

The parasympathetic nervous system.

What neurotransmitter is released by parasympathetic nerves during micturition?

Acetylcholine.

What happens to the detrusor muscle during micturition?

It contracts to expel urine.

What happens to the internal and external sphincters during micturition?

Internal sphincter opens passively; external sphincter relaxes voluntarily.

What part of the brain can override the micturition reflex?

Higher CNS centers in the brainstem and cerebral cortex.

What is micturition?

The process of bladder emptying (urination), involving both voluntary and involuntary control.