Urinary System Flashcards
The urogenital system develops from what type of tissue?
During lateral folding, what ridges appear?
- intermediate mesenchyme (dorsal body wall of embryo)
- urogenital ridge (each side of dorsal aorta)
The nephrogenic cord will give rise to the …?
The gonadal ridge will give rise to the …?
nephrogenic cord = urinary system
gonadal ridge= genital system
What are the 3 sets of kidneys?
Which sets are functional and which are permenent?
pronephroi (never functional; appear@ week 4)
mesonephroi (appear@ week 4; functions briefly for 4 weeks)
metanephroi (begin developing@week 5; permanent kidney @ week 10);S1-S2
What persists after the pronephri degenerates?
What does this become?
pronepheric ducts persist
- becomes the **Wolffian duct **(mesonephric duct)
The mesonephric ducts open into what structure?
The mesonephroi degenerate at the end of the first trimester, their tubules become what adult structure?
- the cloaca (trigone of urinary bladder)
The primordia of permanent kidneys starts developing at what week?
They are functional by what week?
- week 5
- week 8 (mesonephroi)
* urine is secreted into amniotic cavity
* fatus swallows 100s mL of amniotic fluid/day
*fetal waste eliminated by maternal kidneys
By what week are the kidneys in their final abdominal position?
- what rotational change in position takes place?
week 9 (become fixed to suprarenal glands)
- 90 degrees medially; hilum faces medially
(kidneys eventually become retroperitoneal)
How does the blood supply change in the ascending kidney?
How many different positions does it have?
renal arteries:
1st: branches of common iliac arteries
2nd: distal end of the aorta
3rd: new branches from aorta
(3 positions in total)
Accessory Renal Arteries
(Supernumerary renal arteries)
- about 25% of adult kidneys have two to four renal arteries
- usually arise from the aorta
- accessory renal artery to inferior pole of kidney may cross anterior to
ureter + obstruct it = hydronephrosis (distension of renal pelvis + calices with urine)
- if accessory artery is damaged/ligated kidney part supplied = ischemic
Unilateral Renal Agenesis
- left kidney is usually absent
- usually asymptomatic (other kidney = compensatory hypertrophy)
Bilateral Renal Agenesis
failure in development of the metanephric diverticula
- oligohydramnios (b/c little/no urine excreted into amniotic cavity)
- incompatible with postnatal life b/c associated pulmonary hypoplasia**
- ** new developments = potential survival with dialysis & early kidney transplant*
Characteristic facial appearance:
- eyes widely separated
- epicanthic folds (wrinkly skin)
- ears are low-set
- broad nose and flat
- limb defects (lack of space to develop)
Ectopic Kidney
One or both kidneys in abnormal position
failure to alter position during embryo growth
- in pelvis (pelvic kidney) or inferior part of the abdomen (lumbar kidney)
most common = pelvic
Horseshoe Kidney
poles of kidneys are fused; (usually inferior poles)
- lies in the hypogastrium, anterior to the inferior lumbar vertebrae
- usually asymptomatic
- normal ascent is prevented b/c they are caught by the root of inferior mesenteric artery
Ureteropelvic Junction Obstruction (UPJ)
obstruction to urine flow from the renal pelvis to the proximal ureter
_**most common congenital obstruction of the urinary tract**_
- severe uteropelvic atresia => multicystic dysplastic kidney with severely dilated calyces
- kidney consists of grapelike, smooth-walled cysts of variable size; b/t cysts are dysplastic glomeruli + atrophic tubules
Childhood polycystic kidney disease (PCKD)
- kidneys are huge + spongy and contain cysts caused by dilatation of collecting ducts + tubules that compromise kidney function
- autosomal recessive disease (short arm of chromosome 6 (p6))
- associated clinically w cysts of the liver, pancreas, + lungs
- treatment: dialysis + kidney transplant
Wilms’ Tumor (WT)
_**most common renal malignancy of childhood**_
- large, solitary, well-circumscribed mass; (on cut) soft, homogeneous, + tan-gray
- recapitulates different stages of embryologic formation of kidney:
= 3 histologic areas: stromal, blastemal (tightly packed embryonic cells), tubular
Duplications of the Urinary Tract
Cause: division of the metanephric diverticulum
- degree of duplication depends on how extent the division was
- Complete division = double kidney with bifid ureter or separate ureters
* supranumeracy kidneys*
Ectopic Ureter
males: open into neck of bladder or into prostatic part of urethra
- above external urethral sphincter = incontinence NOT common
females: open into bladder neck, urethra, vagina or vestibule of the vagina
- below external urethral sphincter = incontinence IS common
Ureterocele
(Simple vs. Ectopic)
simple ureterocele:
- distal end of ureter has cystlike protrusion into the submucosal layer of the urinary bladder
ectopic ureterocele:
- cystlike protrusion into the submucosal layer of the urinary bladder associated with ectopic ureter + duplication
- -* ureterocele is at the end of ureter from upper renal segment & is located inferior to other ureter opening
What divides the cloaca into the urogenital sinus and rectal sinus?
How is the urogenital sinus further divided?
urorectal septum
urogenital sinus:
- cranial vesicle = bladder
- middle pelvic part = prostatic urethra (M)/ entire urethra (F)
- caudal phallic part = primordium of penis or clitoris
What are the tissue origins of the bladders layers?
What are the tissue origins of the Male & Female urethras?
BLADDER:
(M/F) epithelium = endoderm (vesicle part of urogenital sinus)
(M/F) other layers of its walls = splanchnic mesenchyme
URETHRA:
(most of M/ all of F) epithelium = endoderm (vesicle part of urogenital sinus)
(M/F) connective tissue + smooth m. = splanchnic mesenchyme
How does the allentois contribute to the development of the bladder?
- originally allentois is continuous with bladder
- allentois constricts = urachus
- urachas extendes from umbilicus –> apex of bladder
- in adult, urachus = median umbilical ligament
- (failure of urachus to constrict = urachal cyst or fistula)*
Urachal cysts
- originate from remnants of the epithelial lining of the urachus
- NO connection b/t bladder & umbilicus
Urachal Sinus
persistent inferior end of the urachus that dilates and opens into the bladder
Urachal fistula
entire urachus remains patent , allowing urine to escape from its umbilical orifice
Congenital Megacystis
- large urinary bladder, may result from congenital disorder of the metanephric diverticulum; may associate w dilation of the renal pelvis
= absolute renal failure + **pulmonary hypoplasia; **lethal unless intrauterine treatment is performed
Exstrophy of Bladder
- exposure + protrusion of mucosal posterior wall of bladder
- due to abdominal wall + anterior bladder wall failure
- trigone of bladder + ureteric orifices are exposed
- some cases = penis is divided in two parts
Development of the Female Urethra:
- lower portion of the urogenital sinus (endoderm)
- develops endodermal outgrowths into surrounding mesoderm = urethral glands + paraurethral glands of Skene (homologous to prostate gland)
- vestibule of vagina develops endodermal outgrowths = lesser and greater vestibular glands of Bartholin
Development of the Male Urethra:
- prostatic urethra, membranous urethra, bulbous urethra + proximal part of penile urethra = from lower portion of urogenital sinus (endoderm)
- distal part of urethra (in glans of penis) = solid cord of ectodermal cells growing inward from tip of glans; joins rest of spongy urethra
Development of the Suprarenal Glands:
cortex = mesenchyme; medulla = neural crest cells
- neural crest cells differentiate into chromaffin cells (stain yellow-brown)
- Week 6: cortex begins as aggregation of mesenchymal cells on each side of the embryo b/t root of dorsal mesentery + gonad
- Cortex = very large during fetal period + at birth; grows smaller after birth
- Cortex produces steroid precursors used by placenta for synthesis of estrogen
- At Birth = cortex + medulla (zona fasciculata + zona glomerulosa)
- End of year 3 = zona reticularis is visable
Neuroblastoma (NB)
- common extracranial neoplasm containing primitive neuroblasts (neural crest origin)
- presents in children; found in extra-adrenal (60%) or within the adrenal medulla (40%)
- metastasizes to bone marrow, bone, + lymph nodes.
- -* common lab finding = increased urine vanillylmandelic acid (VMA) + metanephrine levels
Pheochromocytoma (PH)
- rare neoplasm; contains both epinephrine + norepinephrine
- present in adults 40-60 years old; generally found in region of adrenal gland; may be found in extrasuprarenal sites
- associated w persistent or paroxysmal hypertension, anxiety, tremor, profuse sweating, pallor, chest pain, and abdominal pain
- lab findings = increased urine vanillylmandelic acid (VMA) + metanephrine levels, inability to suppress catecholamines with clonidine, + hyperglycemia
- Treatment: surgery or phenoxybenzamine (an a-adrenergic antagonist)
Congenital Adrenal Hyperplasia (CAH)
(Female pseudointersexuality)
- most common cause = mutations in genes for enzymes involved in adrenocortical steroid biosynthesis
- excessive androgen production by suprarenal cortex = masculinization in females
- Female pseudointersexuality = mild clitoral enlargement, complete labioscrotal fusion w a phalloid organ, or macrogenitosomia (in the male fetus)
- cannot synthesized aldosterone = hyponatremia (“salt-wasting”), dehydration + hyperkalemia (hgh K+ levels)
- Treatment = infusion of intravenous saline + long-term steroid hormone replacement (cortisol + mineral-corticoids)
