Renal anat 2 - nephron, filtration system, renal corpuscle, juxtoglomerular apparatus Flashcards
what is the structure of the nephron? (4 main parts)
Renal corpuscle
proximal convoluted tubule
loop of henle (thick and thin loops)
distal convolute tubule
what is the renal corpuscle
the filtration system of the kidneys
describe the components of the renal corpuscle
consists of the glomerulus and bowman’s capsule
Bowman’s capsule: parietal layer (outer) and visceral (inner) layer
pressure in Bowman’s space drives filtration –> fluid is forced into this space
Explain the structure of podocytes in the filtration membrane (include primary, secondary processes and nephrin)
Filtration membrane = glomerulus and podocytes
podocytes: nucleus & organelles
- have primary processes –> give rise to secondary foot processes which interdigitate with neighbouring pedicles
- gaps between secondary process are filtration slits – single layer of protein called nephrin
Role of endothelial cells in glomerular
endothelial cells on the inner surface (podocytes on basal lamina)
porous/leaky –> allows fluid to move out freely where it then gets filtered by the basement membrane
What is the role of the filtration membrane?
allows fluid to go through but not RBC’s and other cells (depends on size etc.)
what goes through the filtration membrane?
water, electrolytes, and small molecules (glucose) and small proteins
Role of mesangial cells in relation to blood pressure?
within the glomerulus
regulate blood flow/pressure in the glomerulus
- move pressure force fluid into the Bowman’s space
Explain the proximal convoluted tubule (PCT) in relation to the filtration system
PCT secrete variety of organic ions
- creatinine (blood creatine rises with kidney damage)
- adrenaline
- penicillin
simple cuboidal epithelium
brush border of microvilli (> surface area)
many mitochondria (very metabolically active)
what is the primary role of the loop of henle?
water reabsorption (control saltiness)
- cells are pumping salt into the inner medulla by thin descending limb – allows water to then be pulled out of limb into the space therefore urine become more concentrated as it moves through the loop of henle
what are the 4 parts of the loop of henle?
thick descending limb
thin descending limb
thin ascending limb
thick ascending limb
- descending loop transition from cuboidal to squamous epithelium (hence epithelium gets thinner)
loop of henle: what limbs are in the outer and inner stripe
outer: thick ascending and descending limb
inner: thin descending and thick ascending
Distal convoluted tubule - compare to PCT
larger lumen (no BB)
less metabolically active with mitochondria
paler cytoplasm
no brush border
cuboidal cells little smaller than PCT
controls Na+, H+ and K+ ions under control of aldosterone (blood pressure control)
Two main cell types of collecting ducts:
principal cells
intercalated cells
Compare principal and intercalate cells of collecting ducts
principal:
- pale, few organelles
- short microvilli
- reabsorb Na+ & water, secrete K+
Intercalated:
- darker, more mitochondria and vesicles
- some microvilli
- secrete H+ reabsorb HCO3-
