Urinary System Flashcards
Metanephric Kidney
- mature kidney in humans
- paired structures
- filters blood
- Artery and vein enter into the kidney at the pelvis
- divides into calyces
- pyramids at the base of the calyx
- ureter exits the kidney
The Renal Nephron
Renal Corpuscle
- glomerulus and capsule that filters blood
Proximal tubule
- convoluted tubule and a straight short duct
Loop of Henle
- Thick descending, thin descending, thin ascending and thick ascending duct
Distal Tubule
- thick ascending duct and thick convoluted tubule
Collecting duct
Renal Corpuslce
Capsule is parietal layer around the outside
Inside is visceral component
- glomerulus
- consisting of highly branched capillaries
- surrounded by cells that facilitate the filtration of the blood
Macula Densa
- highly compacted cells of distal convoluted tubule
- immediately adjacent to the arteriole that goes into the renal corpuslce
- cause juxtaglomerular cells to secrete renin causing an increase in blood flow and blood pressure of the arterioles feeding into the glomerulus
Feedback Loop
- the fluids have gone all the way through to the distal convoluted tubule, which give feedback on the efficiency of the filtration process to the blood vessels which are newly feeding into the renal corpuscle
Glomerulus
- visceral component of the renal corpuscle
- capillaries are covered by epithelial branches of podocytes
- podocytes further branch to form pedicles (filtration slits)
- facilitates filtration of the blood through the structures into the urinary space
- forms primitive filtrate
- filtrate exits through the urinary pole
Mesangial Cells
- play a role in cleaning up the basement membrane surrounding the capillaries
- with constant filtering, you get compounds that accumulate on the capillaries, clogging up the basement membrane
Filtration Membrane
- Fenestrated capillary of kidney does not have a diaphragm
- Sometimes called pseudofenestrated
- Does have a very thick basement membrane which acts as filter of the blood
Podoctyes branch to form pedicles
- There is a slit diaphragm between adjacent pedicles of podocytes
- Filtrate enters into urinary space = Bowman’s space
- Filtrate contains water and very small compounds, many of which will be reabsorbed by tubular component of the nephron
Reabsorption through the tubules
Proximal convoluted tubule
- reabsorbs most of the water and some ions
Descending Thick Tubule
- similar to proximal
- reabsorbs another 15% of water
Descending Thin
- Passively reabsorbs water
Ascending Thin
- Reabsorbs NaCl, but not water
Ascending Thick
- Responsive to aldosterone
- Reabsorbs Na
Distal Convoluted tubule
- responsive to aldosterone
- reabsorbs Na and water
Collecting Ducts
- responsive to vasopressin (ADH) from pituitary
- reabsorbs water back into the body
No water is absorbed on the ascending limb
Vasa Recta
- extensive capillaries around the loop of henle
- important for reabsorbing most of the water and ions
Cortex and Medulla
Cortex
- on the outer surface
- contains only renal corpuscles
Medulla
- only contains tubules
- no renal corpuscles in the medulla
- outer stripe
- Inner stripe
- Inner zone
Outer Stripe
- contains only thick tubules
- Both ascending and descending
- contains collecting ducts
- proximal convoluted tubule has a prominent brush border
Inner Stripe
- Ascending thick
- Descending thin (or ascending thin?)
- Collecting ducts
Inner Zone
- A lot of collecting ducts
- Only thin tubules
Renal Papilla
- all filtrate collects to the renal papilla which goes into calyces and then drain into the ureter
Ureters
- lined by transitional epithelium = urothelium
Contains:
- transitional mucosa
- Lamina propria
- Muscularis
- Adventitia
- Binucleated cells
