Which collagen chain can generate an immune reaction in Goodpasture Syndrome?
Collagen IV alpha3 chain.
Tritiated water = TBW
Mannitol, inulin = ECF
Evans blue = plasma volume
Interstitial water is measured indirectly (ECF - Plasma volume)
ICF measured indirectly
(TBW - ECF volume)
Mechanisms for autoregulation of RBF.
Myogenic: renal afferent arterioles contract in response to stretch.
(increase in P produces increase in R to maintain constant RBF)
Tubuloglomerular feedback: increased renal pressure --> increased delivery of fluid to macula densa which causes constriction of afferent arteriole
What does clearance of PAH measure?
Effective RPF, it underestimates the true RPF by 10%
How do you measure GFR?
Clearance of inulin. It is filtered but not reabsorbed or secreted.
What is an indicator of prerenal azotemia?
Increased BUN/creatinine ratio of >20:1
How does an increase in the plasma [protein] effect the GFR?
It decreases the GFR because of an increase in the osmotic pressure of the glomerular capillary.
Relationship between filtered load, excretion rate, reabsorption and secretion.
If filtered load > excretion rate, then net reabsorption has occurred.
If filtered load < excretion rate, then net secretion has occurred.
Explain glomerulotubular balance.
Occurs in the proximal tubule, the purpose is to maintain a constant fractional reabsorption. If GFR increases, peritubular capillary [protein] and osmotic pressure increase causing more fluid reabsorption.
What special transporter does the TAL contain?
Na/K/2Cl co transporter, aka NKCC2.
What are the loop diuretics, where and what do they act on?
Furosemide, ethacrynic acid, bumetanide.
They inhibit the NKCC2 of the TAL.
What special transporter does the DCT contain?
Na/Cl cotransporter, aka the NCCT.
Cell types of the CD.
Principle cells: reabsorb Na and H2O, secrete K, sensitive to aldosterone and ADH.
Intercalated cells: A (secrete acid) and B (secrete base)
Factors that increase distal K secretion.
1. High K diet
3. Alkalosis (acidosis decreases secretion)
4. Thiazide diuretics
5. Loop diuretics
6. Luminal anions
Which portions of the nephron are impermeable to urea?
DT, CCD and OMCD. IMCD are sensitive to ADH and can reabsorb urea.
How does PTH affect phosphate reabsorption?
It activates adenylate cyclase, generating cAMP which inhibits Na/phosphate cotransport. Thus it causes phosphaturia.
Process for water intake/deprivation.
Change in plasma osmolarity sensed by osmoreceptors in the anterior hypothalamus, which tells the posterior pituitary whether or not to release ADH.