Histology Of Urinary Tract

Question 1

What are the layers of the urinary tract?

Answer 1

Mucosa

• epithelium and lamina propria layers
• contains urothelium layers with uroplakins (which allow for the dome cells to flatten and allow for distention as well as anti-toxic properties)

Submucosa
-amount of layers differs

Muscularis

• 2-3 layers smooth muscles
• very thick in the urinary tract except the urethra

Adventitia
- includes serosa and is only present on the superolateral bladder

Question 2

What do sympathetics do in the urinary tract?

Answer 2

Inhibits smooth muscle contraction of the ureter and detrusor muscle

Promotes smooth muscle contraction of the internal urethral sphincter and urethra

Controls vasomotor control over arterioles and also enhances sodium reabsoprtion in tubules

increases in sympathetics will allow the bladder to expand and retain urine, decrease urine frequency

decreases in sympathetics will prevent the bladder from expanding and promote urine frequency

Question 3

What do parasympathetic do in the urinary tract?

Answer 3

Promotes smooth muscle contraction of the ureter and detrusor muscles

Inhibits smooth muscle contraction of the internal urethral sphincter

May also contribute to the vasomotor regulation of the afferent and efferent arterioles

increasing parasympathetics promotes voiding of the bladder (increases volume) and the feeling of urgency

**Decreasing parasympathetics decreases voiding of the bladder (decreases volume) and the feeling of urgency **

Question 4

What is the purpose of visceral afferents in the urinary tract?

Answer 4

Stretch receptors which detect the degree of distention of the bladder as part of the micturition reflex controlled by the CNS

Question 5

Pyelonephritis vs cystitis vs urethritis

Answer 5

Pyelonephritis
- infection of the renal pelvis and the calyces which leads to neutrophil accumulation in the CD

Cystitis

• inflammation of the bladder mucosa
• can be caused by infection, immunodeficiency, urinary catheterization and chemotherapy
• chronic cystits can lead to unstable urothelium and benign urothelial changes which leads to transitional cell carcinoma

Urethritis

• infection of the ureters
• most commonly caused by coli form bacteria and chlamydia
• causes pain while urinating and dysuria almost always
• *way more common in females than males since their urethras are smaller

Question 6

Why is urothelium very unique?

Answer 6

Possess uroplaquin proteins which make up urothelial plaques along the urothelium cells
- forms a lipid bilayer essentially and both protects from the toxic effects of urine and allows the cells of the urothelium to stretch and flatten to move urine

Question 7

How does development of the urethra differ in women and males?

Answer 7

Women = all of the urethra is generated via the pelvic part of the urogential sinus

Men = prostatic and membranous urethra is derived from the pelvic part IFN the urogential sinus
- spongy urethra = development from phallic portion of the urogential sinus

Question 8

Where do the sympathetics and parasympathetics for the kidney and abdominal ureters arise from?

Answer 8

Lesser splanchnic nerves (T10-11)= sympathetic
- least (T12) and greater = adrenal glands

Pelvic splanchnic and posterior vagal trunk = parasympathetic

both combined make up the renal plexus which innervates the kidney

Question 9

Where do the sympathetics and parasympathetics for the pelvic ureter, bladder and urethra?

Answer 9

Lumbar Splanchnic nerves (L1/2) = sympathetics

Pelvic splanchnic nerves = parasympathetic

both of these make up the inferior hypogastric plexus

sympathetics also make up the vesicular and prostatic plexi

Question 10

What do somatic efferents in the urinary tract do?

Answer 10

Promotes skeletal muscle contractions of external urethral sphincter

Question 11

Where are the possible constrictions of the urinary track?

Answer 11

1st = where the ureter passes over the inferior renal pole

2nd = ureter passes behind testicular and ovarian vessels

3rd = ureter crosses over external iliac vessels (pelvic part)

4th = ureter traverses the bladder wall (intramural part)
- most common site**

Question 12

How does visceral referred pain differ between superior and inferior bladder?

Answer 12

Superior = lower abdominal region/ suprapubic region

Inferior = scrotum

Question 13

Ureterocele

Answer 13

The ureter protrudes into the bladder lumen and swells up due to the detrusor muscle clamping down on it.
- is an example OPG a urinary track blockage and leads to hydroureter and hydronephrosis

Question 14

How does the arterial supply to the kidney and ureter get broken down?

Answer 14

All are branches from the renal artery except #1 (come off abdominal aorta)

1) middle suprarenal and inferior phrenic/superior suprarenal arteries = adrenal glands
2) inferior suprarenal arteries = adrenal glands and superior kidney pole
3) renal artery itself = middle and lower poles of the kidney
4) urethral branches = lower pole, ureter

Question 15

How does the arterial supply to the bladder and urethral get broken down?

Answer 15

All are branches off the internal iliac artery

1) superior vesical arteries and umbilical arteries = urinary bladder and distal ureter
2) inferior vesical arteries and prostatic arteries = prostate and epididymis

Question 16

What is the course of the ureter?

Answer 16

Arises in renal pelvis and travels under gonadal arteries, over the common iliac arteries and under the uterine artery/vas deferens
- because of this course, gynecological procedures often damage the ureter or apply obstruction if not properly.

Question 17

What are the most common points for ureteral obstruction?

Answer 17

Ureteropelvic junction

Pelvic inlet

Ureterovesical junction