Functional Histology Flashcards
What are medullary rays
Where groups of tubules form together in the medulla
Which parts of the nephron are in the medulla and which parts are in the cortex?
Cortex - glomerulus, proximal and distal convoluted tubules
Medulla - loops of henle and collecting duct
During development how does the corpuscle form?
In development a primitive renal tubule will grow up towards a developing glomerulus and envelops it forming the bowman’s capsule. This creates a vascular pole and a urinary pole leaving the bowman’s space.
Describe how the bowman’s space is formed?
There is a visceral layer of the bowman’s capsule surrounding the capillaries (filtering layers) and the perietal layer is formed from the simple squamous epithelium of the bowman’s capsule – between these two layers is the bowman’s space where the ultrafiltrate collects.
What are the main filtering cells in the corpuscle?
Cells called podocytes form the visceral layers forming an extensive mesh work surrounding the capillaries.
How is a filter made from the cells in the corpuscle?
The cpaillary endothelium is fenestrated, the podocytes invest into the endothelium with a mesh of membrane (foot processes) this creates filtration slits. These endothelium and podocytes share a basement membrane optimising filtration, this basement membrane is a gelatinou acellular layer of collagen and glycoproteins.
What is the histological structure of the PCT?
Longest most convoluted of the tubules where reabsorption begins. Made from a simple cuboidal epithelium with pronounced brush border.
What are the 4 parts of the loops of henle?
- Pars recta
- Thin descending limb
- Thin ascending limb
- Thick ascending limb
What is the histological structure of the two thin limbs of the loop of henle?
Both the thin limbs contain simple squamous epithelium and involve no active transport of molecules, neither do they have a brush border.
What is the histological structure of the thick ascending part of the loop of henle?
The thick limb contain simple cuboidal epithelium but without a brush border and active tranport does take place here.
What is the histological structure of the DCT
Cortical, simple cuboidal cells that makes contact with its parent glomerulus, contains numerous mitochondria and when compared to the PCT there is no brush border and has a larger lumen.
What is the Juxtaglomerular apparatus?
A group of cells at the top of a glomerulus that consists of the:
• Macula densa of distal convoluted tubule (dense staining area of the DCT)
• Juxtaglomerular cells of the afferent arteriole of the glomerulus that communicate with the DCT
• Extraglomerular mesangial cells (lacis cells).
What is the histological structure of the collecting duct?
Similar in appearance to the thick limbs of Henele’s loop (simple cuboidal epithelium but without a brush border and active tranport does take place here), but has a larger lumen and more irregular rather than circular.
In the renal pyramid the ducts get progressively larger until they form into a minor calyx. They empty from the renal papilla.
What is the histological structure of the ureter?
Muscular tube – 2 layers of smooth muscle (3rd appears in the lower 1/3 of the ureter. Lined by specialised transitional epithelium or urinary epithelium.
What is the histological structure of the bladder?
3 layers of muscles, outer layer of adventitia and has transitional epithelium still. The inside is lined by urothelium (transition). A layer of umbrella cells cover the surface making the bladder impermeable.
