1. Regulation of tubular reabsorption
1-Glomerulotubular balance : If GFR^ to 150 ml/min so in proximal tubule reabsorption ^from 81 ml/min to 97.5 ml/min.(65% of GFR
A-Intrinsic ability to increase reabsorption when
tubular load increase ?.
B-This act together with autoregulation to
prevent large change in fluid flow in distal tub

2. 2. Peritubular capillary and interstitial fluid physical forces
a. Hydrostatic pr. In capillary Pc opposes -13
b. Hydrostatic pr. In interstitium Pif favors 6
c. Colloid osmotic pr. in capillary πc favors 32
d. Colloid osmotic pr. In intrst. πif opposes -15
____
Net reab. Pr. 10 mmHg
Reabsorption = Kf x Net reabsorptive pr.
12.4 x 10 = 124 ml/min

4. A. ^Arterial pr.^ hydrostatic decreases reabsorption
Change resistance of afferent and efferent __ constrictiondecreases hydrostatic ^ reabsorption.
B. ^Plasma colloid osmotic pr.^ coll. In perit.^ reabs.^Filtration fraction ^[protein] ^reabsorption

5. C. (A,B) if increase reabsorption^ fluids in interstitium^ hydrastatic pr. and decreases colloid pr.decreases reabsorption of fluid from renal tubules
IN GENERAL FORCES INCREASE PERITUBULAR CAPILLARY REABSORPTION ALSO INCREASE REABSORPTIN FROM RENAL TUBULES AND VICE VERSA

9. In general forces increase peritubular cap reabsorption also increase reabsorption from renal tubules and vice versa .

10. 3.PRESSURE NATIURESIS AND PRESSURE DIURESIS 1-GFR autoregulation mmHg 2-Kid diseases increase BP and GFR and urine output 3-Incr BP will increase renal interstitial fluid hydrostatic P and reduce absorption of Na &water and increase urine output 4-reduce angiotensin secretion which decrease aldosterone and both decrease Na absorption & incr urine output

11. 4. Hormonal control :
A.-Aldosteron : on distal tubule and collecting duct Na Cl , H2O reabs. and K+ secretion
-Addison's disease : no aldosterone  loss of Na+ , accumulation of K+
-Conn's syndrome : Na+ retention K depletion
- Increases sodium permeability on luminal side.

12. B. Angiotensin II : on proximal tubule Na Cl,
B. Angiotensin II : on proximal tubule Na Cl, H2O reabsorption, H+ secretion.
Other effects:
1. Stimulates aldosterone secretion
2. Constricts efferent art.
3. Stimulates Na+ reabsorption on Na-K pumps ,Na-H+ exchanger & Na-bicarbonate co-transporter.

15. C.ADH : on distal, coll tubule and coll. duct ^H2O reabsorption.
ADH+V2receptorform cyclic AMP, which activates protein Kinase which moves aquaporin-2 (AQP-2) to luminal membrane then AQP2 fuse together to form water channels.

17. D.Atrial natriuretic peptide ANP :Dilated atria
Decrease Na+ and H2O reabsorption in distal and collecting duct
Also inhibit renin secretion > decrease angiotensin formation.
Important in Heart Failure
E.Parathyroid hormone : Prox. , thick ascending of L.H, distal.decreases PO4- reabsorption and ^Ca++ reabsorption

18. 5.Sympathetic N.S. : ^Na and H2O reabsorption by constricting afferent and efferent arterioles .
It also increases renin and angiotensin II formation.

19. Renal clearance of substance
Useful way of quantitating the effectiveness with which kidneys excrete various substances.
Volume of plasma that is completely cleared of the substance by the kidneys per unit time .
Urinary excretion rate
Cs= (Us xV) GFR x Ps=Us x V Ps
Cs=GFR GFR= Us x V -

22. For creatinine clearance & GFR GFR x Pcr=Ucr x V If GFR decrease the creatinine filtration & excretion decrease & plasma concentration increase

23. CLEARANCE & GFR: Inulin and Creatinine
RENAL PLASMA FLOW RPF : PAH clearance 90% =UxV/P =C
FILTRATION FRACTION=GFR/RPF
Reabsorption=Kf x Net reabsorption force
Kf : Filtration coefficient : measure of permeability and surface area of the capillaries normal=12.4 ml/min/mm Hg

25. Inulin clearance = GFR
Amt. Filtered = Amt. Excreted
- PAH clearance / 0.9 = Renal plasma flow
If the substance is completely cleared from the plasma (by filtration & secretion) , the clearance of substance = to the total renal plasma flow.
Amt. delivered to kidneys in blood= amt. excreted in urine.

26. PAH removed from the plasma by filtration & secretion (90%) called extraction ratio

27. TUBULAR REABSORPTION OR SECRETION If GFR x Ps > Us x V absorption If GFR x Ps < Us x V secretion