The Development of the urinary system Flashcards
Summarise the development of the foetal kidney. (2)
3 systems developing sequentially, with the disappearance of one marking the appearance of the next. Pronephros > Mesonephros > Metanephros.
Describe the first stage in embryological development of the kidney. (3)
The pronephros never functions in humans, but forms the pronephric duct that extends from the cervical region to the cloaca (common outflow for GI and GU tracts). Drives the production of the next stage, the mesonephros.
Describe the second stage in development of the embryological kidney. (5)
The pronephric duct gives rise to the mesonephric duct, which together with the mesonephric tubules form the embryonic kidney. They have no water conserving function. The Mesonephric (Wolffian) duct forms the Vas Deferens, and sprouts the ureteric bud that induces the adult kidney development.
Describe the formation of the adult kidney. (2)
Ureteric bud prompts development of the adult kidney when it expands and branches to form the calyces.
Describe the ascent of the kidney. (3)
The metanephric kidney first appears in the pelvic region, and so undergoes a caudal to cranial shift, creating new blood vessels as it goes instead of dragging its old ones with it.
Explain three anatomical defects that can arise as a failure of the migration of the kidney. (6)
Pelvic kidney - kidney fails to migrate cranially so exists in the pelvic region.
Horseshoe kidney - the kidneys’ caudal poles grow close together and fuse, meaning as the kidney migrates cranially, it gets stuck on the first unpaired branch that has formed, usually the IMA.
Accessory renal arteries - the kidney is unable to get rid of the old blood supplies as it migrates cranially, so the kidney will have more than one renal artery.
Describe the role of the urogenital sinus. (4)
Created from the hindgut by the urorectal septum, and is continuous with the urachus.
Differentiates to form the bladder and urethra from one part, and the genitals from another (with contributions from the Wolffian and Mullerian ducts).
It joins with the mesonephric ducts, prompting the ureteric bud to form the adult kidney.
Describe the role of the urorectal septum. (2)
The urorectal septum creates the urogenital sinus. It ruptures the cloacal membrane and opens the hindgut to the amniotic cavity after separating the forming bladder (urogenital sinus) from the hindgut.
Describe the outcomes of a persistent cloaca and a persistent urachus. (4)
Cloaca - common outflow tract for the bladder, hindgut and vagina. Defect in urorectal septum and urogenital sinus splitting. Means lacking urinary function, bowel fuction or sexual function depending on how far up the common outflow occurs.
Urachus - a persistant connection between the bladder and the umbilicus resulting from the failure of the urachus to close, leading to a urachus formation and urine being able to drain out of the umbilicus.
Describe Hypospadias. (2)
When the genital folds don’t fold properly, so the urethra opens onto the ventral surface of the penis rather than the glans.
Describe what would happen if the ureteric bud were to split during development of the adult kidney. (2)
There could be ectopic urethral openings (urethra, vagina), leading to urinary incontinence as no sphincters exist here.
Describe cloacal extrophy. (2)
When things that normally would be formed from one of the outflow tracts (eg bladder, intestines) are found outside the abdominal wall because the cloaca opened up anteriorly.
