Week 8 Urinary Bladder/ Continence

Question 1

What are the two main functions of the bladder?

Answer 1

Temporary store of urine- hollow organ- distensible

Assists in expulsion of urine- during voiding musculature contracts and sphincter relaxes

Question 2

What is the structure of the inside bladder?

Answer 2

Folding internal lining of muscle - rugae

Question 3

What are the important external divisions of the bladder (describe them)?

Answer 3

Apex- located superiorly, pointing towards pubic symphysis, connected to umbilicus by the median umbilical ligament- remnant of urachus
Body- between apex and fundus- main part
fundus- located posteriorly, triangular shape, tip of triangle pointing backwards
neck- formed by convergence of fundus and two inferolateral surfaces, joins bladder to urethra

Question 4

What is and what makes up the trigone?

Answer 4

Triangular area located within the fundus, has smooth walls

Where 2 ureters enter-orifices and internal urethral orifice

Question 5

What is the main muscle of the bladder- how many layers and what kind?

Answer 5

Detrusor muscle- 3 muscle layers- inner longitudinal, circular the outer longitudinal- retains integrity when stretching
Smooth muscle

Question 6

Where does the detrusor muscle receive innervation from?

Answer 6

Parasympathetic- contracts to see

and sympathetic- relaxes to stretch and fill

Question 7

Describe the two sphincters- muscle type, neural control, function

Answer 7

Internal urethral sphincter- circular smooth muscle, autonomic control, prevents seminal regurgitation during ejaculation
External urethral sphincter- skeletal muscle, voluntary control, relaxes during micturition it relaxes to allow urine flow

Question 8

Describe how the sympathetic, parasympathetic and somatic nerves communicate with the bladder- nerve roots, nerve and result

Answer 8

SNS- hypogastric nerve T12-L2, relaxation of detrusor muscle- promote storage and urine retention
PNS- pelvic nerve S2-S4, increased signals from this nerve cause contraction from the detrusor muscle- stimulates micturition
Somatic- voluntary control over micturition- innervated external urethral sphincter via pudental nerve S2-S4- can cause it to constrict (storage stage) or relax (micturition)

Also in addition to efferent supply described above also afferent (sensory) nerves that report to brain- in bladder wall and signal need to urinate when bladder full

Question 9

Where is the bladder derived from embryonically?

Answer 9

Hindgut