The Kidney Diuretic Action, Electrolytes

1
The KidneyDiuretic Action, Electrolytes

• RTH 245, Spring 2000
• Joseph S. DiPietro, Ph.D., RRT

2
Basic Structure

• The Nephron (cortex)
• Multilevel Filtration System
• Bowmans Capsule
• Glomerulus
• Henles Loop--Ascending and Descending
• Proximal Distal Tubules

3
Proximal Tubule
Bowmans Capsule
Blood Flow
Glomerulus
Water, Glucose, Amino Acids, Small
Proteins Minerals
Efferent arteriole
Water, Glucose, Amino Acids, Small
Proteins, Minerals
Collecting tubule
Distal Tubule
Ammonia, H
Artery
Henles Loop
Afferent Arteriole
Vein
Creatinine Medications
4
REABSORPTION SIDE
SECRETION SIDE
Glucose Amino Acids Uric Acid Na K Ca Mg HCO
3 HPO4 Cl- H20 Urea
PAH Creatinine H Pencillin
Proximal Tubule
Loop of Henle
NaCl
NH3 H K
Cl- H2O HCO3
Distal Tubule
Na
H2O Urea
Collecting Tubule
Peritubular Blood Vessel
5
The Renin-Angiotensin SystemBlood Pressure
Maintenance
RENIN ANGIOTENSINOGEN
ANGIOTENSIN I
ANGIOTENSIN II
ALDOSTERONE SECRETION
PERIPHERAL VASOCONSTRICTION
Na and Water Retention
Increased Plasma Volume
INCREASED BLOOD PRESSURE
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Kidney Functions

• Filtration
• Excretion
• Water Balance
• Electrolyte Balance
• Reabsorption
• Blood Pressure Maintenance

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Excretory Functions

• Maintains plasma osmolality _at_285 mOsm by varying
  water excretion
• Maintains plasma concentration of electrolytes
• Maintains pH near 7.40 by eliminating excess H
  or reabsorbing HCO3-
• Excretes nitrogenous end-products from protein
  burning i.e., urea, uric acid, creatinine

8
Non-Excretory Functions

• produces RENIN--to regulate blood pressure
• produces ERYTHROPOIETIN--stimulates bone marrow
  to produce red cells
• metabolizes vitamin D to its active form
• degrades insulin
• produces prostaglandins

9
The Nephron, and Diuretic Sites of Action
Afferent Arteriole
Efferent Arteriole
Glomerulus
1
CA inhibitors
Distal tubule
Proximal tubule
NaCl
4
Thiazides
Na, HCO3-
H
K
Na
2
Osmotic
5
K -sparing
Descending
NaCl
Ascending
H2O
3
Loop
Henles Loop