Lecture 33: Ureters, Bladder, Urethra

Question 1

Describe transitional epithelium and where it is found:

Answer 1

• Stratified, rounded cells
• Flatten when stretched
• For protection from urine (dangerous)
• found within the bladder and ureters and start of urethra

Question 2

Where do ureters come from and what is their role?

Answer 2

• Arise from each renal pelvis at each hilum
• Slender tubes that carry urine from kidneys to bladder
• Descend retroperitoneally through abdomen, vertically from hila

Question 3

How is urine moved to the bladder?

Answer 3

• Peristaltic waves move urine to bladder via the ureters

Question 4

How is the muscularis of the ureters different to the GIT?

Answer 4

Inner layer is longitudinal, outer layer is circular

The circular fibers close over the longitudinal fibres to stop backflow

This is the opposite for the muscularis in the small/large intestine.

Question 4

What is the histological structure of ureters?

Answer 4

Three layers:
– Transitional epithelium
– Muscularis (inner longitudinal, outer circular)
– Adventitia - outer covering of fibrous connective tissue

Also has: Folded protective protein plaques on inner surface

Question 5

Where do ureters enter the bladder and what function can they have due to this?

Answer 5

• Run obliquely through the wall of bladder at its posterolateral corners

Acts as a sphincter/valve:
- compressed by increased bladder pressure to prevent backflow (the wall will stretch out and close the ureters off when the bladder becomes full)

Question 6

What is the trigone?

Answer 6

-triangular region between 2 openings of entry of ureters and 1 opening for urethra

Question 7

What is the function of the bladder?

Answer 7

• Stores and expels urine (needs rugae to allow stretch for storage)

Also requires muscle allowing the bladder to be emptied

When full, the bladder expands without great increase in pressure (~500ml)

Question 8

What is the function of the urethra?

Answer 8

• Thin walled muscular tube
  -carries urine out of bladder

Question 9

What is the structure and location of an empty vs full bladder?

Answer 9

Empty bladder:
- Pyramidal
- Lies within the pelvis

As bladder fills:
- Becomes more spherical
- Expands superiorly into abdominal cavity
- Can be palpated above pubic symphysis

Question 10

What is the location of the bladder in males vs females?

Answer 10

• Male bladder
  – Anterior to rectum
  – Superior to prostate gland (wraps around urethra)
• Female bladder
  – Anterior to vagina and uterus

Question 11

What is the name of the muscle in the bladder and is it smooth or skeletal? Also name the fibers it has and its overall function:

Answer 11

Thick smooth muscle layer called detrusor
- Longitudinal, circular and oblique fibres (not in distinct layers)
- Contractions to expel urine from bladder into urethra during urination (collapses on itself)

Question 12

What are the three features of the bladder wall?

Answer 12

• Folded into rugae for expansion
• Muscosa of transitional epithelium
• Thick smooth muscle layer called detrusor

Question 13

What epithelium(s) are present in the urethra and what protective feature does this epithelium have?

Answer 13

– Transitional epithelium near bladder
– Columnar epithelium
– Stratified squamous epithelium near external opening

• Mucus glands to protect epithelium from urine

Question 14

What are the differences between male and female urethra?

Answer 14

• Female:
  – shorter (~5cm)
  – separate from reproductive system
• Male:
  – longer (~25cm)
  – part of reproductive system
  – initial section surrounded by prostate gland (produces seminal fluid)
  – 3 sections: prostatic, membranous, spongy/penile

Question 15

Give the location, function and control of internal/external urethral sphincters:

Answer 15

Internal urethral/urinary sphincter:
Location = Junction of bladder and urethra
Detrusor muscle (smooth muscle)
- Under Involuntary control

External urethral/urinary sphincter:
-Located where urethra passes through the urogenital diaphragm made of Skeletal muscle
- Under Voluntary control

Question 16

Explain the process of urination:

Answer 16

• Bladder fills with urine and expands
• AP from stretch receptors to brain
• Urgency increases as signals increase
• Internal sphincter relaxes
• Conscious relaxation of external sphincter (urination occurs)

Question 17

Which of the following statements is INCORRECT about the bladder?
A. Detrusor muscle forms the bladder wall
B. It is lined with transitional epithelium
C. It is a collapsible sac which stores and expels urine
D. The trigone is a triangular area between the openings of the ureter and two urethras
E. When empty, the bladder collapses along folds called rugae

Answer 17

D

Jorja don’t get this one wrong

Question 18

Name three places in the urinary tract you would find transitional epithelium.

Answer 18

Ureters, Bladder, start of urethra (close to the bladder)

Question 19

Does the ureter have submucosa?

Answer 19

NO

no need for secretion here

Question 20

What structure does the urethra in both males and females need to pass through?

Answer 20

Urogenital diaphragm (pelvic floor)