Renal system Flashcards
- Renal structure - Nephron
- Nephron 1 million
- Cortical area mostly.
- Nephron structure:
- renal corpuscle (glomerulus and bowmans capsule)
- juxtoglomerular apparatus
- renal tubules
- Renal struc - Glo/Bowmans cap
Made up of: parietal epithelium, urinary space, visc epi or podocytes (feet neg charged), glo basement membrane, capillaries, mesangium
- Renal struc - glom basement membrane
- Neg charged also.
- Less permeable to proteins.
- Injury to membrane and slits results in loss of neg charge and protein filters through.
- Renal struc - cap/mesangium
Capillaries - fenestrations to allow flow
Mesangium - macrophages, cells contractile
- Renal struc - juxtoglomerula- app
Jux cell- located afferent artery
- Sense stretch
- Produce and release renin
- Macula densa- located distal tubule near glo and sense Na
- Renal vessel
Receives 25% CO
Flow from cortex to medulla
More O2 needed in medulla for ATP
Susceptible to ischemic injury
- Autoregulation- tubuloglom feedback
Macula densa senses NaCl changes.
Decreased Na > renin release > afferent vasodilation, efferent vasoconstriction = Increase GFR.
Opposite with ^ Na.
Juxt cells - assess perfusion pressure. ^ MAP- afferent vasoconstriction.
Goal- ^ flow to glomerulus.
- Neural regulation of kidney blood flow
Sympathetic nerve -
renal artery/arterioles cause vasoconstriction
^ renin production
- Humoral reg of cort/med flow
Vasoconstriction: Angiotension II, ADH (vasopressin), endothelin
Vasodilation: NO, adenosin, Prostaglandins, dopamine
- Renal function test - Creatinine Clearance
Best indicator of renal func.
Overestimates GFR.
Normal - 120ml/min et 1.0 in serum.
UxV / P
- BUN
^ when GFR decreases.
Will rise only when 60% of renal function lost.
- BUN/Cr Ratio
10:1, 20:1 with prerenal failure.
Normal with RF as both are high.
- Fractional excretion of Na+
Integrity of tubular reabsorptive function.
If ^ 1% then tubular or glom damage.
- UA
Neg for rbc, wbc, protein, casts.
If rbc then blood into tubules.
If wbc then inflam process.
If epi cell then tub lumen degeneration or tub necrosis.
- Urine Formation - glomerular filtration
Fluid movement from cap to tub.
Filtrate devoid of cells or protein.
Nephron loss leads to compensatory hyperfiltration.
- Urine formation
Reabsorp- mvmt of substances, lytes from tub fluid into blood.
Secretion - secretion of sub from blood into tub fluid.
Concentration of tub fluid/urine - occurs in loop of henle and again in collecting ducts under ADH and aldosterone influence.
Renal production of rbc
Erythropoietin production stimulated by decrease in PaO2.
RF causes anemia.
Vit D
Made from cholesterol in skin by UV light.
Vit D inactive taken to liver. changed et taken to kidney to form Vit D under PTH influence.
Stimulates Ca and Phos absorp by sm intestine.
Stimulates osteoclast to reabsorp bone to increase Ca concen in extracellular fluid (subsides when Ca absorbed by sm intes).
- Renal regulation of fluid
Reabsorb in prox tubule along with Na reabsorp.
Aldosterone - controls Na absorp in dist tub and collect duct.
Vasopression (ADH) - targets water reabs in collect duct.
- Renal regulation of Na
Absorbed in proximal tubule and loop.
Cl passively follows.
Final reabsorp in dist tub and collect duct.
- Renal regulation of K
Same as Na.
Influenced by :
Serum K levels
Acid-base - H and K exchange for each other. Acidosis with ^ H = ^H into cell and K comes out. This decrease in K also decreases K secretion. Opposite with alkalosis.
Plasma osmolality - dist tub reabsorb Na from tub filtrate in exchange for K secretion.
Aldosterone - acts on collect duct to stimulate K secretion in exchange for Na reabsorp.
- Renal reg of calcium
Reabsorp in proximal tub.
In loop, tied to Na and k reabsorp.
In dist tub, influenced by PTH, calcitonin, acid base.