Urinary Flashcards
Vasculature to kidneys
All end arteries!
Renal -> interlobar -> arcuate (bet cortex and medulla) -> intralobular ->
portal system: afferent arteriole -> glomerulus -> efferent arteriole -> vasa recta into medulla
Veins:
convoluted tubules -> interlobular
vasa recta -> arcuate veins
Lobes of kidney
Medullary pyramid + cortical material
8-12 total
Divided into lobules with one collecting duct and medullary ray
Flow of urine through nephron
Corpuscle -> proximal convoluted tubule -> Henle's loop - thick descneding, thin (descending), thick ascending -> distal convulted -> collecting tubule
Renal corpuscle
Glomerulus (capillary)
Bowman’s capsule (dev’t as hand in glove) - visceral and parietal layers with Bowman’s/urinary space in between
Bowman’s capsule
Visceral - highly specialized
- endothelium with fenestrae
- podicytes share basement membrane, send primary and secondary processes/pedicles to basement membrane (cell body is between capillaries)
-> filtration slit - 30-40 nm wide between interlaced pedicles, thin diaphragm across
- thick basement membrant with negatively charged GAGs (ions, proteins)
- mesangial cells in middle - contractile?, clean-up?
Parietal layer - simple squamous
Urinary pole - junction to prox convoluted tubule (cuboidal with microvilli)
Pressures in glomerular
Blood hydrostatic - smooth muscle of afferent and efferent arteriole
Capsular hydrostatic + blood osmotic
GBHS + CHP + BCOP = GFP
Proximal convoluted tubule
Resorbs most of filtrate (180 L/d vs 1.5 L urine)
- 2/3 Na+, all glucose and amino acids (also 3x longer than distal CT)
Cuboidal with microvilli (brush border)
Lots of mitochondria - very active in resorption - appear pink/striated
Nuclei are not as prominent as distal tubule
Straight prox tubule = thick loop of Henle
Lobule
= division of cortex!!
Medullary ray in middle = colleting duct and straight tubules
Surrounded by labyrinth = corpuscles and convoluted tubules
Medullary stripes into medulla are from loops of Henle
Loop of Henle
Critical for concentration of urine
Thin descending - simple squam - permeable to Na and H2O -> flow out to interstitial osmolality
Thick ascending limb - simple squam - pumps out Na+ but impermeable to water
-> high osmolality of interstitium, low in filtrate
-> H2O passively out - mostly from collecting duct via aquaporins (dependent on ADH)
Vasa recta - same concentrations as interstitium (flows in and out as blood loops down)
Countercurrent multiplier and countercurrent exchange -> Na concentrations
Distal convoluted tubule
Smaller cells -> more prominent nuclei
No brush border
Less common than proximal (shorter)
Ascending thick limb is similar
Macula densa is specialized piece of DCT
JGA
Contains JGA at junction with ascending limb
- macula densa - modified epithelium, more columnar, packed against glomerulus - JG/granular cells - modified smooth muscle - make renin and release (mostly into efferent arteriole), visible pink granules - lacis - extraglomerular - may transmit signals
RAAS and ATII function
JGA -> renin -> angiotensinogen -> ATI -ACE> AT II
Functions of ATII:
-> adrenal cortex (zona glomerulosa) -> aldosterone -> Na+/H20 resorption
- direct Na+ resorption (Na-K exchange)
- vasoconstriction
-> post pituitary -> ADH release -> aquaporins
- potentiates SNS
Collecting tubules
Collecting tubules -> ducts
Well defined cellular borders
Simple cuboidal -> columnar cells
Collecting duct
of Bellini
Increase in size as tubules add
Transition of cuboidal -> columnar
Release through area cribrosa into minor calyx (lined with urothelium)
Principal cells - water absorptin (aquaporins)
Intercalated cells - alpha, beta secrete H+ and HCo3
- lighter nuclei, not evenly spaced
Ureter
Muscular
Urothelium
Smooth muscle - 2 layers -> peristalsis
