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Cm5 renal function

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by : Ms. Crizelda Liwanag

by : Ms. Crizelda Liwanag

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    Cm5 renal function Cm5 renal function Presentation Transcript

    • • Renal Anatomy • Renal Blood Flow • Renal Physiology • Urine formation – Glomerular Filtration – Tubular Reabsorption – Tubular Secretion
    • Renal Anatomy
    • kidney What is the average 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
    • kidney
    • 2 regions of the kidney Cortex Medulla • Renal corpuscles • Loop of Henle • Proximal tubules • Vasa recta • Distal tubules • Collecting tubules
    • What is the functional unit of the kidney? of the kidney? NEPHRON
    • Renal Blood Flow 2 1 3a 3b
    • Renal Blood Flow
    • 1 2 6a 3b 3a 4a 7b 5a 8b 6b 4b 5b
    • Renal Physiology MAJOR FUNCTIONS The Body’s Filters: removing toxins & metabolic waste products • Ultrafiltration • Endocrine function • Osmolarity regulation • Volume regulation • Acid-base regulation
    • ultrafiltration
    • ultrafiltration Of the renal blood 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
    • ultrafiltration The kidneys possess extraordinary mechanisms to reabsorb water while removing metabolic waste by-products and toxins. How is kidney function measured? GFR Glomerular Filtration Rate
    • Endocrine function 1. Erythropoietin 2. Active form of vitamin D (1,25- dihydroxy vitamin D3) 3. renin
    • 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
    • ↓BP ↓PLASMA VOL ↑OSMOLARITY ↓venous pressure ↓venous return ↓ atrial pressure ↑ ADH secretion ↑ tubular permeability to water ↑ water reabsorption ↓ water excretion ↓ urine volume ↑ urine osmolarity
    • Volume Regulation Regulation of ECF volume thru the • Renin-Angiotensin-Aldosterone (RAA) pathway • Atrial Natriuretic Factor (ANF)
    • ↓BP ↓PLASMA VOL ↓Na ↑ Renal symp nerves ↓ arterial pressure ↓ renal arterial pressure ↑ renin secretion (into afferent arteriole) ↑ plasma angiotensin (from adrenal cortex) ANF ↑ aldosterone secretion ↑ tubular Na reabsorption ↓ Na excretion
    • Volume Regulation Atrial Natriuretic Factor (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
    • Acid Base Regulation
    • Acid Base Regulation • To excrete X’s alkali: – Na2HPO4 – NaHCO3 • To excrete X’s acid: – NH4Cl – (NH4)2SO4 – NaH2PO4
    • What is the first step in urine formation? GLOMERULAR FILTRATION
    • Glomerular Filtration The filtration of a solute that is not reabsorbed or secreted Unit: mL/min Affected by: hydrostatic & oncotic pressure, Renin-angiotensin-aldosterone system, structure
    • Glomerular Filtration Substances retained: • Substances filtered: • Blood cells • Water • Serum proteins • Smaller molecules (MW: <70,000) – Ions – Amino acids – Glucose – Urea – Creatinine – Uric acid – ammonia
    • Glomerular Filtration • Approximately 20% 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)
    • What barriers are there to the passage of the filtrate? • Endothelium (glomerular capillary) • Basement membrane – Lamina rara interna – Lamina densa – Lamina rara externa • Podocytes (visceral layer)
    • Glomerular Filtration
    • Glomerular Filtration • To pass through the filtration barrier: – <4 nm in size – Threshold
    • Glomerular Filtration
    • Tubular Reabsorption • The movement of substances (by active or passive transport) – from the tubular ultrafiltrate into the peritubular blood or the interstitium by the renal tubular cells.
    • Tubular Reabsorption Substances reabsorbed by active transport: • Glucose, Amino acids, Salts (PCT) • Chloride (LOH) • Sodium (DCT)
    • Tubular Reabsorption Substances reabsorbed by passive transport: • Water (all nephron parts except ascending limb) • Urea (PCT, ascending limb) • Sodium (ascending limb)
    • Tubular Secretion • The movement 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
    • Tubular Secretion • Substances incompletely metabolized – E.g. thiamine • Substances not metabolized at all – E.g. radiopaque contrast media / mannitol • Substances not normally present – Certain drugs
    • SUMMARY • Close your notes...
    • •Glomerulus FILTRATION: water (ADH not 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
    • •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+
    •  Collecting Duct Hypertonic or Hypotonic filtrate REABSORPTION: Water (ADH required), Na+, Cl-, Urate, Urea, CO2 SECRETION: K+, H+