lecture 30 - ureters, bladder and urethra Flashcards
What is transitional epithelium?
Stratified rounded cells arranged randomly that stretch when flattened
What is the function of transitional epithelium in the urinary system?
Protection - prevents leaking of urine into underlying tissues by ensuring epithelium cells remain together when stretched
Where do the ureters arise?
From each renal pelvis at the hilum
What do the ureters transport?
Urine from the kidneys to the bladder
Do the ureters descend retroperitoneally or intraperitoneally from the hila?
Retroperitoneally
What aids in moving urine from the kidneys to the bladder via the ureters?
Peristaltic waves
What are the 3 layers of the ureter?
Transitional epithelium, muscularis, adventitia
What are the 2 layers of the muscularis in the ureter?
Inner longitudinal and outer circular
What is the outermost layer of the ureter?
Adventitia - outer covering of fibrous connective tissue
What is found on the inner surface of the ureter?
Folded protective inner protein plaques
How do the ureters enter the bladder?
Run obliquely through the bladder wall at its posterolateral corners
How is backflow from the bladder to the ureter prevented?
The ureter acts as a sphincter/valve and is compressed by increase bladder pressure to prevent back flow
What is the urinary bladder?
A collapsible muscular sac that stores and expels urine
What feature of the bladder helps it to collapse when empty?
Rugae - temporary folds
What is the trigone of the bladder?
Triangular region between 2 openings of the entry of the ureters and 1 opening for the urethra at the bottom
What is the shape of an empty bladder?
Pyramidal
Where does the bladder sit when empty?
Within the pelvis
What is the shape of a full bladder?
Spherical
Where does the bladder sit when full?
Expands superiorly into the abdominal cavity
What is the relative location of the bladder in males?
Anterior to rectum and superior to the prostate gland
What is the relative location of the bladder in females?
Anterior to the vagina, uterus and rectum
What epithelium lines the urinary bladder wall?
Transitional epithelium
What is the name for the thick smooth muscle layer in the bladder?
Detrusor
What types of muscle fibres are found in the detrusor?
Longitudinal, circular and oblique smooth muscle fibres
Is there a motility pattern in expulsion of urine from the bladder?
No -strong contractions expel urine rapidly
What is the urethra?
A thin walled muscular tube that drain the urine from the bladder out of the body
How does the epithelium change in the urethra?
Transitional near bladder then columnar then stratified squamous near external opening
What feature of the urethra epithelium protects it from urine?
Mucus glands
What is the name for the external opening of the urethra?
External meatus/orifice
What are the features of the male urethra?
Long, part of reproductive system, initial section surrounded by the prostate gland, has 3 sections - prostatic, membranous, spongy/penile
What are the features of the female urethra?
short, seperate from the reproductive system
What are the 3 sections of the male urethra?
Prostatic, membranous, spongy/penile.
What are the 2 sphincters of the bladder that control flow into the urethra?
Internal and external urethral/urinary sphincters
What muscle is the internal urethral sphincter made of?
Continuation of the Detrusor muscle (smooth muscle) of the bladder
Is the internal urtheral sphincter under involuntary or voluntary control?
Involuntary
Where is the external urethral sphincter located?
Where the urethra passes through the urogenital diaphragm
What type of muscle makes up the urogenital diaphragm?
Skeletal muscle
What is the process of urination?
Bladder fills and expands, triggering stretch receptors that signal, with increasing urgency, to the brain. The internal sphincter unconsciously relaxes and then the external sphincter is consciously relaxed to release urine.
