بسم الله الرحمن الرحيم

1. بسم الله الرحمن الرحيم ﴿و ما أوتيتم من العلم إلا قليلا﴾ صدق الله العظيم الاسراء اية 58

2. Kidney By Dr. Abdel Aziz M. Hussein Lecturer of Medical Physiology

4. Test Yourself The cortex of the kidney contains the • a. hilus. • b. glomeruli. • c. perirenal fat. • d. renal pyramids. • e. renal pelvis.

5. A layer of fibrous connective tissue that surrounds each kidney is the • a. hilum. • b. renal pelvis. • c. renal sinus. • d. renal capsule. • e. perirenal fat.

6. Renal Blood Flow

7. Renal Blood Flow Def.: • It is the fraction of CO that supplies both kidneys i.e. renal fraction RBF

8. Renal Blood Flow Value: • ¼ CO or 1200ml/min or 4 ml/ 1 gm kidney tissues Significance: • Is high to ensure high GFR NOT to supply excess O2 for excess metabolism

9. Renal Blood Flow Distribution: A) 10% supply non-functioning structures of kidney • a) capsule • b) pelvis • c) perinephric fats B) 90% functioning structures • Cortex → 88% - 89% • Medulla → 1- 2%

10. Renal Blood Flow 4-5 ml/ min 1 gm Cortex 0.7- 1.0 ml /min/ 1gm Outer Medulla 0.2 – 0.25 ml /min/ 1gm Inner Medulla

11. Low Medullary RBF 2. High length of vasa recta 1. Small number of vessels 3. High viscosity of medullary blood flow

12. Regulation of Renal Blood Flow

13. Regulation of Renal Blood Flow Mechanisms: • 2 mechanisms;

14. Autoregulation of RBF Def.,: • It is the ability of the kidney to keep its RBF and GFR at nearly normal levels in the face of reasonable changes of ABP Range of Autoregulation: • From 80 – 180 mmHg • is not perfect 100% since RBF and GFR show changes by less than 10% with previous range of ABP

15. RBF mL / min GFR 80 mmHg 180 mmHg ABP

16. Autoregulation of RBF Significance: • To minimize effect of change of ABP on GFR and hence on Na+ and water excretion or helps to decouple renal regulation of salt and water excretion from fluctuation of ABP Mechanism of Autoregulation: • Mainly by variation of afferent arteriolar resistance • Two theories; • Myogenic theory • Tubuloglomerular –ve feedback theory

17. Tubuloglomerular –Ve Feedback Theory Decreased RBF Adenosine GFR High NaCl V.C. of afferents Increased RBF Increased ABP

18. Tubuloglomerular –Ve Feedback Theory Angiotensin II Renin release PGI2 GFR Low NaCl V.D. of afferents Decreased RBF Decreased ABP

19. Myogenic Theory Increase of RBF to Normal Level V.D. wall of arteriole Decreased stretch of vessel wall Decrease of ABP ↓ Renal Blood Flow

20. Myogenic Theory Decrease of RBF to Normal Level V.C. wall of arteriole Increased stretch of vessel wall Increase of ABP ↑ Renal Blood Flow

21. Extrinsic Regulation of RBF • The extrinsic regulation of RBF is mediated by nervous and chemical factors • Nervous Factors: sympathetic N.S. • Humeral Factors: autacoids and hormones A) Angiotensin II (strong V.C. agent) • At low concentration → V.C. of efferent → protect GFR • At high concentration → generalized V.C. → ↓GFR and RBF b) ADH, serotonin, and endothelin → V.C. of renal blood vessels →↓ RBF c) Prostaglandins (PGE2 & PGI2), NO, ANP, dopamine and bradykinin → V.D. d) Hormonal changes during pregnancy → ↑ RBF by 50% e) High protein diet → ↑ RBF by 30%

22. Angiotensin converting enzyme inhibitors (ACEIs) are a group of drugs that inhibits AII thus dilate the efferent arteriole and reduce GFR. • These drugs also reduce the hyperfiltration occurring in DM, thereby minimizing the occurrence of nephropathy.

23. Nervous Regulation of RBF No change in RBF Minimal effect on B.V. No change in GFR Mild Sympathetic N.S. stimulation

24. Nervous Regulation of RBF Moderate decrease in RBF Equivocal V.C. of both afferent and efferent Minimal decrease in GFR Moderate Sympathetic N.S. stimulation

25. Nervous Regulation of RBF Marked decrease in RBF Intense V.C. of both afferent and efferent Marked decrease in GFR Renal Shutdown Severe Sympathetic N.S. stimulation

26. Given these structures: • 1. major calyx • 2. minor calyx • 3. renal papilla • 4. renal pelvis • Choose the arrangement that lists the structures in order as urine leaves the collecting duct and travels to the ureter. • a. 1,4,2,3 • b. 2,3,1,4 • c. 3,2,1,4 • d. 4,1,3,2 • e. 4,3,2,1

27. Which of these structures contains blood? • a. glomerulus • b. vasa recta • c. distal tubule • d. Bowman’s capsule • e. both a and b

28. The juxtaglomerular cells of the ………….and the macula densa cells of the………… form the juxtaglomerular apparatus. • a. afferent arteriole, proximal tubule • b. afferent arteriole, distal tubule • c. efferent arteriole, proximal tubule • d. efferent arteriole, distal tubule

29. Given these blood vessels: • 1. afferent arteriole • 2. efferent arteriole • 3. glomerulus • 4. peritubular capillaries Choose the correct order as blood passes from an interlobular artery to an interlobular vein. • a. 1,2,3,4 • b. 1,3,2,4 • c. 2,1,4,3 • d. 3,2,4,1 • e. 4,3,1,2

30. Urine Formation

31. Urine Formation

32. Urine Formation

33. Glomerular Membrane

34. Glomerular Membrane Def., • It the membrane through which the plasma is filtered Composition: 3 layers; • Capillary endothelium • Basement membrane • Capsular epithelium

36. Glomerular Membrane

37. Glomerular Membrane

38. Glomerular Membrane

39. Capillary Endothelium • Capillary endothelium • Fenestrations • Single layerof fenestrated endothelium (each fenestra is about 50-100 nm). • Total fenestrations represent about 9% of total surface area of the capillary. • Acts as a screen to preventblood cells and platelets from contact with basement membrane • Blood cells • Solutes

40. Capillary Endothelium • Basement Membrane • Formed of network of fibrils embedded in a jelly-like matrix. • Thickness 0.2-0.3 m. • Acts as a sieve allowing retention of plasma proteins main barrier.

41. endothelium Basement m. cells PP others Blood Glom. Memb. Cap. epith. Bowman space

42. Bowman's capsular epithelium • Bowman's capsular epithelium • Single layer of podocytes, each has a finger like process that make a space with each other called slit pores of about 5 nm in diameter.

43. Bowman's capsular epithelium • Bowman's capsular epithelium Functions: • a) Laydown & maintain B.M. • b) Phagocytose the escaped macromolecules.

44. Factors Affecting Permeability of Glomerular Membrane

45. Factors Affecting Permeability of Glomerular Membrane • 3 factors affecting permeability of G.M. • Molecular weight and size • Shape and configuration • Charge

46. 1) Molecular Size and Weight Size: • Radius below 18 A0 freely filtered. • Radius between 18- 36 A0 filtered by rate dependent on the charges; cationic more filtered than anionic of same radius (as the filtering membrane has net negative charge). • Radius more than 36 A0 not filtered.

47. Blood components 18A 36A + - endothelium Cap. Epith. 18 – 36A Basement m. Bowman space

48. 1) Molecular Size and Weight Weight: • Molecular weightbelow 7.000 freely filtered. • Molecular weight above 70.000difficult to pass. • In between 7.000 – 70.000 depend on charge & configuration.

49. Blood components 7000 70.000 + - endothelium Cap. Epith. 7000 – 70.000 Basement m. Bowman space

50. 2) Shape and Configuration • Glomerular membrane has a net hole or cylindrical pore of 7.5 – 10 nm wide • Substances of shape & configuration similar to the holes of the glomerular membrane  freely pass & vice versa.