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Cm5 renal function
- 1. • Renal Anatomy •Renal Blood Flow • Renal Physiology • Urine formation – Glomerular Filtration – Tubular Reabsorption – Tubular Secretion
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- 3. kidney What is theaverage weight of the kidney? 115-170 g What is its average size? 11 cm in length, 6 cm in width, 3 cm thick What is the rate of blood flow into the kidney via the renal artery? 600 mL/min
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- 5. Cortex • Renal corpuscles •Proximal tubules • Distal tubules Medulla • Loop of Henle • Vasa recta • Collecting tubules 2 regions of the kidney
- 6. What is thefunctional unit of the kidney? of the kidney? NEPHRON
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- 11. Renal Physiology MAJOR FUNCTIONS TheBody’s Filters: removing toxins & metabolic waste products • Ultrafiltration • Endocrine function • Osmolarity regulation • Volume regulation • Acid-base regulation
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- 13. ultrafiltration Of the renalblood flow, how much is filtered by the glomerulus? 125 mL/min How many liters of blood is filtered by the kidney each day? 180 liters How much urine is produced per day? 1.5 liters
- 14. ultrafiltration The kidneys possessextraordinary mechanisms to reabsorb water while removing metabolic waste by-products and toxins. How is kidney function measured? GFR Glomerular Filtration Rate
- 15. Endocrine function 1. Erythropoietin 2.Active form of vitamin D (1,25- dihydroxy vitamin D3) 3. renin
- 16. Osmolarity regulation ADH –synthesized in the hypothalamus & released in the posterior pituitary in response to an increase in osmolarity as sensed by osmoreceptors in the anterior hypothalamus
- 17. ↓BP ↓PLASMA VOL↑OSMOLARITY ↓venous pressure ↓venous return ↓ atrial pressure ↑ ADH secretion ↑ tubular permeability to water ↑ water reabsorption ↓ water excretion ↓ urine volume ↑ urine osmolarity
- 18. Volume Regulation Regulation ofECF volume thru the • Renin-Angiotensin-Aldosterone (RAA) pathway • Atrial Natriuretic Factor (ANF)
- 19. ↓BP ↓PLASMA VOL↓Na ↑ Renal symp nerves ↓ renal arterial pressure ↑ renin secretion (into afferent arteriole) ↑ plasma angiotensin (from adrenal cortex) ↑ aldosterone secretion ↑ tubular Na reabsorption ↓ Na excretion ↓ arterial pressure ANF
- 20. Volume Regulation Atrial NatriureticFactor (ANF) • Secreted by the cells in the atria of the heart to inhibit Na+ reabsorption in the kidneys • Inhibits secretion of aldosterone which stimulates Na+ reabsorption
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- 22. Acid Base Regulation •To excrete X’s alkali: – Na2HPO4 – NaHCO3 • To excrete X’s acid: – NH4Cl – (NH4)2SO4 – NaH2PO4
- 23. What is thefirst step in urine formation? GLOMERULAR FILTRATION
- 24. Glomerular Filtration The filtrationof a solute that is not reabsorbed or secreted Unit: mL/min Affected by: hydrostatic & oncotic pressure, Renin-angiotensin-aldosterone system, structure
- 25. Glomerular Filtration Substances retained: •Blood cells • Serum proteins • Substances filtered: • Water • Smaller molecules (MW: <70,000) – Ions – Amino acids – Glucose – Urea – Creatinine – Uric acid – ammonia
- 26. Glomerular Filtration • Approximately20% of the volume of plasma that passes through the glomerular tuft is caught in Bowman’s space and is called the glomerular filtrate. • At this point, the filtrate is iso-osmotic with plasma and is called an ultrafiltrate. (sp. gr. 1.010 +/-0.002 ; pH 7.4)
- 27. What barriers arethere to the passage of the filtrate? • Endothelium (glomerular capillary) • Basement membrane – Lamina rara interna – Lamina densa – Lamina rara externa • Podocytes (visceral layer)
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- 30. Glomerular Filtration • Topass through the filtration barrier: – <4 nm in size – Threshold
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- 32. Tubular Reabsorption • Themovement of substances (by active or passive transport) – from the tubular ultrafiltrate into the peritubular blood or the interstitium by the renal tubular cells.
- 33. Tubular Reabsorption Substances reabsorbedby active transport: • Glucose, Amino acids, Salts (PCT) • Chloride (LOH) • Sodium (DCT)
- 34. Tubular Reabsorption Substances reabsorbedby passive transport: • Water (all nephron parts except ascending limb) • Urea (PCT, ascending limb) • Sodium (ascending limb)
- 35. Tubular Secretion • Themovement of substances (by active or passive transport) – from the peritubular blood or the interstitium into the tubular ultrafiltrate by the renal tubular cells • To secrete substances the kidney is unable to eliminate via ultrafiltration
- 36. Tubular Secretion • Substancesincompletely metabolized – E.g. thiamine • Substances not metabolized at all – E.g. radiopaque contrast media / mannitol • Substances not normally present – Certain drugs
- 37. SUMMARY • Close yournotes...
- 39. •Glomerulus FILTRATION: water (ADHnot required)., Na+, Glucose, K+, Cl-, Urea, Urate, Uric Acid, Proteins, Amino acids, Bicarbonates, Creatinine, Phosphate, Inulin, PAH REABSORPTION: -- SECRETION: -- •Proximal Tubule Isotonic filtrate FILTRATION: -- REABSORPTION: Water (ADH not required), Na+, Glucose, K+, Cl-, Urea, Urate, Uric Acid, Proteins, Amino acids, CO2
- 40. •Proximal Tubule SECRETION: Creatinine,Hydrogen, PAH •Loop of Henle Hypertonic filtrate REABSORPTION: Water, Na+, Cl-, Urate, Urea, CO2 SECRETION: -- •Distal Tubules Area of dehydration (where ADH acts) Iso or hypotonic filtrate; most common area of cast form’n REABSORPTION: Water (ADH required), Na+, Cl-, Urate, Urea, CO2 SECRETION: K+, Uric Acid, H+
- 41. Collecting Duct Hypertonicor Hypotonic filtrate REABSORPTION: Water (ADH required), Na+, Cl-, Urate, Urea, CO2 SECRETION: K+, H+