T13. PHYSIOLOGY OF THE URINARY TRACT Flashcards
(25 cards)
Why is urine elimination episodic?
Due to storage and neural control.
Where is the urinary bladder located?
On the floor of the pelvic cavity.
What connects kidneys to the bladder?
Ureters.
What is the bladder’s muscle called?
Detrusor.
How many layers does the detrusor have?
Three.
What does the mucosa of the bladder form?
Rugae.
What is the function of rugae?
Allow bladder distension.
What happens to rugae when bladder fills?
They flatten.
What is normal bladder capacity?
500 ml.
What is maximum bladder capacity?
700–800 ml.
What initiates the micturition reflex?
Bladder stretch.
Where are stretch signals sent?
To the pons.
What does the pons activate?
Parasympathetic neurons.
What does parasympathetic input cause?
Detrusor contraction and internal sphincter relaxation.
What muscle allows voluntary urination control?
External urethral sphincter.
Is the micturition reflex voluntary?
No, it’s involuntary.
Can the brain override the micturition reflex?
Yes, via the pons.
Where do detrusor signals go first?
Sacral spinal cord.
What does the pons decide?
If urination is timely.
What happens if urination is timely?
Pons excites detrusor, relaxes internal sphincter.
What happens if urination is untimely?
Pons keeps external sphincter contracted.
What type of sphincter is under voluntary control?
External urethral sphincter.
What system excites the detrusor muscle?
Parasympathetic nervous system.
What is the role of spinal interneurons?
Relay commands from the pons.
