30 Flashcards
What type of epithelial cells would you find in the
nephron loop?
Cuboidal worth microvilli brush boarder at the closest part to PCT, simple squamous, cuboidal with few microvilli at part closest to DCT
Name the two capillary beds associated with the
nephron.
Glomerular and peritubular
Which type of nephron is important for the production of
concentrated urine?
Juxtamedullary nephrons
Features of Transitional epithelium - what is it for?
• Stratified, rounded cells
• Flatten when stretched
• For protection.
(Stops substances in urine from being exposed to underlying tissue, urine contains a lot of waste that are toxic and acidic, superficial cells are umbrella cells - apical surface dome shaped - have features that stops urine leaking between the cells, the produce cytocertin that has a water proofing effect, stops fluid from transversing layer of cells, they have a lot of tight junctions at their apical surface, lots of desmosomes connecting adjacent cells stops them separating, umbrella cells can secrete proteins called Europlacans and those proteins can assemble at the apical surface and form plarcs - waxy plates that protect epithelial surface from urine)
Where do ureters arise form?
• Arise from each renal pelvis at each hilum
What are ureters?
• Slender tubes that carry urine from kidneys to bladder
Where do ureters descend?
• Descend retroperitoneally through abdomen, vertically from hila
What moves urine to bladder inside ureters ?
• Peristaltic waves
move urine to
bladder
What kind of epithelium in renal pelvis
Transitional epithelium
Level of the hilus
First lumbrical vertbrae
Ureter histology
Three layers of the ureter
– Transitional epithelium
– Muscularis (inner longitudinal, outer circular) – Adventitia- outer covering of
– Folded protective protein plaques on inner surface
How do ureters run through the wall of the bladder - what can it act as?
• Run obliquely through the wall of bladder at its posterolateral corners
– Acts as a sphincter/valve:
compressed by
increased bladder
pressure to
prevent backflow
What is the urinary bladder?
Collapsible muscular sac
What does the Urinary bladder do?
- stores and expels urine
Urinary bladder
- full vs empty
- When empty the bladder collapses along folds (rugae)
- When full, the bladder expands without great increase in
pressure (~500ml)
What do the Ureters do?
-carry urine from kidneys to bladder
What does the Bladder wall contain?
- contains muscle for expulsion of urine
What are Rugae in the bladder
-Folds that allow bladder to expand
What is the Trigone
-triangular region between 2 openings of entry of ureters and 1 opening for urethra
What does Urethra do?
-carries urine out of bladder
Yes
Empty bladder vs as bladder fills
Empty bladder:
- Pyramidal
- Lies within the pelvis
As bladder fills
- Becomes more spherical
- Expands superiorly into abdominal cavity
- Can be palpated above pubic symphysis
Location in males and females
Bladder
Male bladder:
- anterior to rectum
- superior to prostate gland (wraps around urethra)
Female bladdder:
- anterior to vagina and uterus
Urinary bladder wall
Features
- Folded into rugae for expansion
- Muscosa of transitional epithelium
- Thick smooth muscle layer called detrusor
- Longitudinal, circular and oblique fibres (no differentiation)
- Contractions to expel urine from bladder into urethra during
urination
Name three structures that protect the urinary tract.
- Transitional epithelium
- Protein plaques
- Entrance to bladder prevents back flow
Name the muscle that forms the wall of the bladder.
What is its function?
Detrusor muscle (involuntary)
Expels urine
What is the urethra
Thin walled muscular tube
What does the Urethra do?
Drains urine from the
bladder out of the body
How does epithelium change between bladder and external opening
– Transitional near bladder
– Columnar along most of it (with goblet cells, Mucus glands to
protect epithelium from, protect form ascending bacteria)
– Stratified squamous near external opening
Male vs female urethra
Female:
- shorter (~5cm)
- seperate from reproductive system
Male
- loner (~25cm)
- part of reproductive system
- initial section surrounded by prostate gland (produces seminal fluid)
- 3 sections: prostatic, membranous, spongy/penile
Urethral sphincterS
Internal urethral/urinary sphincter
- Junction of bladder and urethra
- Detrusor muscle
- Involuntary control
External urethral/urinary sphincter
- Located where urethra passes through the urogenital diaphragm
- Skeletal muscle
- Voluntary control
Urination
- 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
Compare and contrast the structure of the epithelium lining the proximal
convoluted tubule with the structure of the epithelium lining the ureters. How
do the different cellular structures of these epithelia relate to their function?
