Lecture 30: THE URETERS, BLADDER AND URETHRA Flashcards
How are transitional epithelium cells?
Stratified, rounded
What happens to transitional epithelium cells when stretched?
They flatten
What is the purpose of transitional epithelium?
For protection from urine (waste product) returning to the underlying tissues
Where do the ureters arise from?
The renal pelvis at each hilum
What are the ureters?
Slender tubes that carry urine from kidneys to bladder
Where do the ureters travel?
Descend retroperitoneally through the abdomen vertically from hila (has some curves)
What moves urine to the bladder?
Peristaltic waves and gravity
What are the layers of the ureter (inner to outer)?
Transitional epithelium, muscularis, adventiita
How is the muscularis of the ureter?
Inner longitudinal and outer circular
What is the adventitia?
Outer covering of FCT
What is on the inner surface of the ureter?
Folded protective waxy protein plaques
How do the ureters enter the bladder?
They run obliquely through the wall at its postolateral corners
What does the ureter act as?
A sphincter/valve which is compressed by increases bladder pressure to prevent backflow
What is the urinary bladder?
A collapsible muscular sac
What does the urinary bladder do?
Stores and expels urine
What does the urinary bladder do when empty?
Collapses along folds (rugae)
What does the urinary bladder do when full?
Expands without great increase in pressure
What is the volume of the urinary bladder?
Approximately 500ml
What are rugae?
Folds that allow the bladder to expand
What is the trigone?
Triangular region between 2 openings of entry of ureters and 1 opening for urethra
What is the shape of an empty bladder?
Pyramidal
Where is the bladder found when empty?
Lies within the pelvis
What happens to the shape of the bladder as it fills?
It becomes more spherical
Where is the bladder found when filling?
It expands superiorly into the abdominal cavity
What can be done to the bladder when full?
It can be palpitated above the pubic symphysis
Where is the male bladder found?
Anterior to the rectum and superior to the prostate gland
What wraps around the male urethra?
The prostate gland
Where is the female bladder found?
Anterior to vagina and uterus
What is the urinary bladder wall folded into?
Rugae for expansion
What is the mucosa of the urinary bladder?
Transitional epithelium
What is the muscle of the urinary bladder?
Thick layer of smooth muscle called detrusor
What fibres are in the detrusor?
Longitudinal, circular and oblique
What does detrusor do?
Contractions expel urine from the bladder into the urethra during urination
What is the urethra?
A thin walled muscular tube
What does the urethra do?
Drains urine from the bladder out of the body
How does the epithelium change in the urethra?
Transitional near the bladder, then columnar and stratified squamous near external opening
Why is the epithelium transitional near the bladder in the urethra?
Because it needs to be able to stretch as urine enters
Why is there columnar epithelium in the urethra?
Mucous to protect epithelium from urine (has mucus glands)
What is the external opening of the urethra called?
External meatus/orifice
Why is the epithelium stratified squamous at the external opening of the urethra?
Protection from abrasion
What is the length of the female urethra?
Approximately 5cm
Is the female urethra part of the reproductive system?
No, it is separate
What is the length of the male urethra?
Approximately 25cm
Is the male urethra part of the reproductive system?
Yes
What is the initial section of the male urethra surrounded by?
Prostate gland which produces seminal fluid
What are the sections of the male urethra?
Prostatic, membranous and spongy/penile
Where is the internal urethral/urinary sphincter?
Junction of bladder and urethra
What is the muscle of the internal urethral/urinary sphincter?
Detrusor muscle (smooth muscle under involuntary control)
Where is the external urethral/urinary sphincter?
Where the urethra passes through the urogenital diaphragm
What is the muscle of the external urethral/urinary sphincter?
Skeletal muscle under voluntary control
What happens when the bladder fills?
It expands and causes an action potential from stretch receptors to be sent to the brain
What happens as urgency to urinate occurs?
Increasing signal to the brain
What sphincter relaxes first?
Internal sphincter and then conscious relaxation of the external sphincter
