Where does the urinary system originate from?
Name the 3 systems that develop which lead to the formation of the urinary system
1) Pronephros 2) Mesonephros 3) Metanephros
Where does the pronephros appear and what function does it serve?
Appears in the cervical region Duct forms which drives the development of the mesonephros
Where does the mesonephros system appear? What function does it serve?
Appears caudal to the pronephric region 2 functions:
1) Serves as an embryonic kidney, but unable to conserve water
2) Sprouts the ureteric bud which induces development of the kidney proper.
Where does the metanephros system appear? What function does it serve?
The metanephros system is made up of the ureteric bud and the metanephric blastema which becomes the kidney Function - differentiates into the kidney proper
Where do the kidneys develop and where is their final position?
Kidney appears in the pelvic region and undergoes a caudal to cranial shift to rest in its final position in the lumbar region
Define renal agenesis and what causes it.
• Occurs when the ureteric bud fails to interact with intermediate mesoderm
• Formation of only 1 or no kidneys occurs
Define duplication defects and their consequences,
• Ureter can be duplicated with one ureter going to the correct place in the bladder and another ureter terminating at a different site; this can be in the urethra or vagina (in women).
• Leads to urinary incontinence or frequent UTIs.
Define a urorectal fistulae
urinary tract and rectum connect due to a defect in the urorectal septum.
Define exstrophy of the bladder
Protrusion of the urinary bladder through a defect in the abdominal wall.
How does a horseshoe kidney occur?
As kidneys start to ascend they rotate laterally and the poles become close enough to each other to fuse. They then get stuck on the inferior mesenteric artery.
How do accessory renal arteries develop?
Develops when blood supplies established as the kidneys ascend aren’t apoptosed. Only supply part of the kidney and means a blockage wont kill the entire kidney.
What is the cloaca?
Early in development, the GI, urinary and reproductive tracts terminate at a single structure – the cloaca.
What is the function of the urorectal septum?
Separates the bladder and urethra from the GI tract. Creates the urogenital sinus
What does the urogenital sinus become?
bladder and urethra
What are the 4 parts of the male urethra?
Preprostatic Prostatic Membranous Spongy
What areas of the kidney do the cortical renal corpuscle occupy?
PCT and and DCT in the renal cortex Ascending and descending limb loop into the outer zone of the medulla
What areas of the kidney do the juxtamedullary renal corpuscle occupy?
PCT and DCT in the renal cortex Ascending and descending limb loop into the inner zone of the medulla
Define the podocytes
Cells that wrap around the glomerulus and the capilary endothelium with filtration slits to allow small molecules to leave the blood.
What epithelia do PCT have?
Simple cuboidal epithelia with pronounced brush border
What are the 4 parts of the loop of Henle? What epithelia does each part have?
• Consists of 4 parts:
o Pars recta
o Thin descending limb – Dips down into the medulla, simple squamous epithelia
o Thin ascending limb – same as thin descending limb
o Thick ascending limb – Simple cuboidal epithelium, active transport
How would you differentiate DCT from PCT?
No brush border and larger lumen than PCT
What 3 components are the juxtaglomerular apparatus made up of?
• Macula dense of DCT
• Juxtaglomerular cells of afferent arteriole of glomerulus
• Extraglomerular mesangial cells
What is the function of umbrella cells on the bladder?
Make epithelium impermeable and able to stretch
Label the histology of the bladder