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Chapter 20, part B

Chapter 20, part B. Integrative Physiology II: Fluid and Electrolyte Balance. Sodium Recycling: Recycling and Excretion. Ascending loop of Henle H 2 O impermeable Na + Active Transport To ECF Gradient Diffuses to blood Collecting Duct: Aldosterone regulates

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Chapter 20, part B

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  1. Chapter 20, part B Integrative Physiology II: Fluid and Electrolyte Balance

  2. Sodium Recycling: Recycling and Excretion • Ascending loop of Henle • H2O impermeable • Na+ Active Transport • To ECF • Gradient • Diffuses to blood • Collecting Duct: • Aldosterone regulates • Na+ recycled or excreted

  3. Mechanism of Na+ Selective Reabsorption in Collecting Duct • Aldosterone: steroid H from adrenal cortex • Stimulates Na+ uptake (& K+ secretion) •  channel synthesis

  4. Mechanism of Na+ Selective Reabsorption in Collecting Duct Figure 20-12: Aldosterone action in principal cells

  5. Angiotensin Pathway: Maintains BP , Volume & Osmolarity Angiotensinogen, ANGI, ANG II, rennin, & ACE Figure 20-13: The renin-angiotensin-aldosterone pathway

  6. Artial Natruretic Peptide: Regulates Na+ & H2O Excretion • Hormone from myocardial cells • Stimulates: hypothalamus, kidney, adrenal, & medulla

  7. Artial Naturetic Peptide: Regulates Na+ & H2O Excretion Figure 20-15: Atrial natriuretic peptide

  8. Potassium Balance: Critical for Excitable Heart & Nervous Tissues • Hypokalemia – low [K+] in ECF, Hyperkalemia - high [K+] • Reabsorbed in Ascending Loop, secreted in Collecting duct

  9. Potassium Balance: Critical for Excitable Heart & Nervous Tissues Figure 20-4: Osmolarity changes as fluid flows through the nephron

  10. Potassium Balance: Critical for Excitable Heart & Nervous Tissues Figure 20-12: Aldosterone action in principal cells

  11. Response to Dehydration & Osmolarity Imbalance • Thirst & "salt craving", or avoidance behavior • Integrated circulatory & excretory reflexes

  12. Response to Dehydration & Osmolarity Imbalance Figure 20-17 : Homeostatic compensation for severe dehydration

  13. Acid/Base Homeostasis: Overview • Acidosis:  plasma pH • Protein damage • CNS depression • Alkalosis:  plasma pH • Hyperexcitability • CNS & heart • Buffers: HCO3- & proteins • H+ input: diet & metabolic • H+ output: lungs & kidney

  14. Acid/Base Homeostasis: Overview Figure 20-18: Hydrogen balance in the body

  15. Kidney Hydrogen Ion Balancing: Proximal Tubule • H+ & NH4+ secreted into lumen and excreted • HCO3- is reabsorbed

  16. Kidney Hydrogen Ion Balancing: Proximal Tubule Figure 20-21: Proximal tubule secretion and reabsorption of filtered HCO3-

  17. Kidney Hydrogen Ion Balancing: Collecting Duct • Type A Intercalated cells excrete H+ absorb HCO3- • Type B intercalated cells absorb H+ secrete HCO3-

  18. Kidney Hydrogen Ion Balancing: Collecting Duct Figure 20-22: Role of the intercalated cell in acidosis and alkalosis

  19. Classifications of Acute Kidney Injury and Chronic Kidney Disease.

  20. Pathophysiological Features of Acute Kidney Injury Leading to Chronic Kidney Disease.

  21. Figure 1 • An overview of the pathogenesis of CKD progression. Although there is considerable interaction between BPdependent and BP-independent initiating mechanisms, BP-dependent mechanisms predominate in hypertensive CKD states. BP independent mechanisms may modulate hypertensive injury and also contribute to CKD progression in normotensive states. AR, autoregulation; BP, blood pressure; CKD, chronic kidney disease; NO, nitric oxide; RAAS, renin–angiotensin–aldosterone system; ROS, reactive oxygen species

  22. Summary • Electrolyte balance depends on integration of circulatory, excretory and behavioral physiology • Water recycling and ECF/plasma balance depends on descending loop of Henle and vasopressin regulated collecting duct for conservation • Osmolarity depends on aldosterone and angiotensin pathway to regulate CNS & endocrine responses • Along with respiration, proximal tubule and collecting duct cells reabsorb or excrete H+ & HCO3- to balance pH

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