functional histology of the kidney Flashcards
what is the renal corpuscle
the Bowmans capsule and the glomerulus
what are the 3 stages of blood filtration ?
label the renal corpuscle
describe the proximal convoluted tubule
- function - reabsorption from the ultrafiltrate
label a PCT epithelial cell
describe the loop of henle
- function - reabsorption from the ultrafiltrate via passive flux
- lined with thin squamous epithelial cells
describe the ascending loop of henle and the distal convoluted tubule
- function - blood homeostasis
- Regulated active transport and ion exchange (Na+/K+, H+/HCO3-)
DCT : - Cuboidal epithelium – thicker than squamous, to reduce passive fluxes and accommodate organelles
- Many mitochondria to fuel active transport. Can show as a pale or striped basal area in H&E-stained sections.
- Few, short microvilli (unlike PCT)
describe the collecting duct and tubule
- Transport of urine to ureter
- Water homeostasis: passive reabsorption of water, regulated through epithelial permeability
- Cuboidal to columnar epithelium, to prevent unregulated passive flux of water (and urea)
- Dense membranes at cell contacts.Function unclear – probably also helping to prevent passive flux.
label this section of kidney cortex at medium magnification
describe the histology of a normal glomerulus
A: afferent arteriole
BC: Bowman’s capsule
PC: beginning of proximal convoluted tubule
White = fluid: blood or ultrafiltrate.
describe the PCT and DCT in the cross section
DC: distal convoluted tubulesCells palerTubule & cells smallerLuminal surface smoother.
Rest are PCTBigger tubules & cellsWispy material in lumen (fixed protein).
what is the juxtaglomerular apparatus ?
Where DCT loops back to meet arterioles of same nephron
label the cells of the juxtaglomerular apparatus
what are the functions of the cells of the juxtaglomerular apparatus ?
- Macula densa - senses [Na+] in the DCT fluid. Appears to signal to….
- Juxtaglomerular cells - release renin – more so in response to lower [Na+] in DCT. Renin indirectly increases vascular tone and sodium resorption.
- Lacis cells – function unknown. (Signalling between the other two?) Also called extraglomerular mesangial cells.
label this cross section of ureter
describe the transitional epithelium
- A special stratified epithelium, found only in ureters and bladder
- Specialized to be impermeable to urine
- Changes appearance on stretching
- Appearance is like stratified squamous epithelium, except biggest cells are apical
- (Stratified squamous epithelium = big basal cells, flat apical cells)
describe the Plaques of specialized (urine-resistant) plasma membrane in apical cells of transitional epithelium
Distended (bladder full):
These impermeable, rigid membrane patches (plaques) protect apical cells from toxic urine.
Contracted (bladder empty):
The rigid plaques are invaginated forming pits, allowing bladder volume to decrease.
