Urine Transport, Storage, and Elimination

Question-and-answer style flashcards covering ureters, bladder anatomy, micturition reflex, urethra, and related control mechanisms.

What is the primary function of the ureters?

To transport urine from the kidneys to the urinary bladder.

At which kidney region do the ureters exit?

The hilum.

How do the ureters enter the urinary bladder, and why is this important?

They enter at an oblique angle, which allows bladder distension to compress the ureter openings and prevent urine backflow.

What type of epithelium lines the ureter mucosa?

Transitional epithelium.

Name the two smooth-muscle layers in the ureter muscularis.

Inner longitudinal layer and outer circular layer.

What mechanism propels urine through the ureters?

Peristaltic waves of smooth-muscle contraction.

Which divisions of the autonomic nervous system innervate the ureters?

Both sympathetic and parasympathetic divisions.

What is the normal urinary bladder capacity in adults?

Approximately 700–800 mL.

Where is the urinary bladder located relative to the pubic symphysis?

Posterior to the pubic symphysis.

What are rugae in the bladder, and what is their function?

Mucosal folds that allow bladder expansion during filling.

Name the three layers of the detrusor muscle.

Inner longitudinal, middle circular, and outer longitudinal smooth-muscle layers.

Which autonomic nerves control the detrusor muscle?

Both sympathetic and parasympathetic nerves.

What is the trigone of the bladder?

A triangular, funnel-shaped area between the ureteral openings that directs urine toward the urethral orifice.

Which urethral sphincter is involuntary?

The internal urethral sphincter.

Which urethral sphincter is under voluntary control?

The external urethral sphincter.

Define micturition.

Urination (voiding) – the process of expelling urine from the bladder.

What bladder volume typically triggers the micturition reflex?

About 200–400 mL of urine.

Which receptors detect bladder stretch and initiate the micturition reflex?

Baroreceptors (stretch receptors) in the bladder wall.

Where are the two neural centers involved in the micturition reflex located?

The pons (pontine micturition center) and the sacral spinal cord (S2–S4).

Parasympathetic stimulation during micturition causes which two key actions?

Contraction of the detrusor muscle and relaxation of the internal urethral sphincter.

What effect does inhibition of the pudendal (somatic) nerve have during micturition?

It relaxes the external urethral sphincter, allowing urine to pass.

How does the cerebral cortex provide conscious control over urination?

By sending inhibitory signals to the pontine micturition center, preventing detrusor contraction and keeping both sphincters closed.

Why are infants unable to voluntarily control urination?

Their cerebral cortex and its inhibitory pathways to the micturition centers are not yet fully developed.

What is the consequence of a spinal cord injury above S2 on bladder control?

Loss of voluntary control, leading to reflexive urination and possible incontinence.

Describe the epithelium lining the external urethral orifice.

Stratified squamous epithelium.

List the two urethral openings.

Internal urethral orifice (from bladder) and external urethral orifice (to exterior).

How does the female urethra differ from the male urethra?

The female urethra is shorter and carries only urine, whereas the male urethra is longer, runs the length of the penis, and carries both urine and semen.