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Flashcards in renal histology Deck (16):

what are the functions of the kidney

- filter blood to remove waste as urine
- regulate water, salt, acid-base balance
- regulate BP
- produce hormones/enzymes (e.g. renin)


describe a nephron

- is the smallest functional unit of the kidneys
- it is a filtering tubule
- there are around 1 million per kidney
- blood filter attached to a tubular epithelium


what cells line the renal corpuscle

podocytes (envolope capillaries)
parietal epithelial cells (squamous)


what are the 3 main components of the glomerular filtration barrier

- endothelium (wall of capillary)
- glomerular basement membrane
- podocytes


function of the glomerular filtration barrier

-physical barrier
- charged selective barrier (repels negative charges)
e.g. albumin
- restricts large proteins


describe the glomerular capillary endothelium

- negatively charged glycocalyx (repels negatively charged proteins)
- holes which are permeable to small molecules


describe the glomerular basement membrane

- made up of collagen and negatively charged proteoglycans
- has a dense core and less dense outer layer
- acts as a physical (inner) and charged barrier (outer)


describe the podocytes

- adhere to GBM
- forms slits through primary and secondary processes
- covered in a negatively charged glycocalyx coat


define podocyte effacement

a disease damaging the glomerular filter - causing a leaky filter


describe the role of mesangial cells

- SM cells packed inside capillary tuft
- maintain tuft shape
- produce ECM
- loss of function results in glomerular scarring from overproducing ECM


describe the contents of the juxtaglomerular apparatus

JG cells - modified SM cells that line the afferent arteriole and can secrete renin
macula densa cells - special cells lining thick ascending limb, sense salt conc in filtrate (flow rate)
extraglomerular mesangial cells


describe the function of the juxtaglomerular apparatus

- if the concentration of salt in the distal tubule is high it will induce afferent arteriolar vasoconstriction
- if the flow/salt concentration is low then it will induce renin release


features of proximal tubule cells

- cuboidal epithelium
- brush border (microvilli) to increase surface area
- pinocytosis
- lateral processes and infoldings to increase surface area


features of thin limb cells

- thin squamous epithelium
- role in water reabsorption as part of LOH
- nuclei bulge into lumen


features of distal tubule cells

- no brush border
- no pinocytosis
- cuboidal
- lateral processes and infoldings


features of collecting duct cells

-cuboidal to columnar epithelium