Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 20b Integrative Physiology II: Fluid and Electrolyte Balance.

Similar presentations


Presentation on theme: "Chapter 20b Integrative Physiology II: Fluid and Electrolyte Balance."— Presentation transcript:

1 Chapter 20b Integrative Physiology II: Fluid and Electrolyte Balance

2 Potassium Balance Regulatory mechanisms keep plasma potassium in narrow range Aldosterone plays a critical role Hypokalemia Muscle weakness and failure of respiratory muscles and the heart Hyperkalemia Can lead to cardiac arrhythmias Causes include kidney disease, diarrhea, and diuretics

3 Behavioral Mechanisms Drinking replaces fluid loss Low sodium stimulates salt appetite Avoidance behaviors help prevent dehydration Desert animals avoid the heat

4 Disturbances in Volume and Osmolarity Figure 20-16

5 Volume and Osmolarity Table 20-1 (1 of 3)

6 Volume and Osmolarity Table 20-1 (2 of 3)

7 Volume and Osmolarity Table 20-1 (3 of 3)

8 Blood volume/ Blood pressure Osmolarity accompanied by osmolarity inhibits CVCC + Para- sympathetic output Sympathetic output Heart Force Rate Cardiac output Vasoconstriction Peripheral resistance Distal nephron Vasopressin release from posterior pituitary Arterioles Volume H 2 O reabsorption + + H 2 O intake Thirst + + Volume conserved DEHYDRATION CARDIOVASCULAR MECHANISMS RENIN-ANGIOTENSIN SYSTEM RENAL MECHANISMS HYPOTHALAMIC MECHANISMS Carotid and aortic baroreceptors Hypothalamic osmoreceptors Osmolarity and Blood pressure Granular cells GFR Flow at macula densa Angiotensinogen ANG I ACE ANG II Aldosterone Na + reabsorption Distal nephron + Hypothalamus Adrenal cortex Atrial volume receptors; Carotid and aortic baroreceptors Renin Volume and Osmolarity Homeostatic compensation for severe dehydration Figure 20-17

9 Volume and Osmolarity Figure (5 of 6) Blood volume/ Blood pressure Osmolarity accompanied by osmolarity inhibits CVCC + Para- sympathetic output Sympathetic output Vasoconstriction Peripheral resistance Distal nephron Vasopressin release from posterior pituitary Arterioles Volume H 2 O reabsorption + H 2 O intake Thirst + Volume conserved DEHYDRATION RENIN-ANGIOTENSIN SYSTEM RENAL MECHANISMS Osmolarity and Blood pressure Granular cells GFR Flow at macula densa Angiotensinogen ANG I ACE ANG II Aldosterone Na + reabsorption Distal nephron + Adrenal cortex Renin

10 Volume and Osmolarity Figure (6 of 6) Blood volume/ Blood pressure Osmolarity accompanied by osmolarity inhibits CVCC + Para- sympathetic output Sympathetic output Heart Force Rate Cardiac output Vasoconstriction Peripheral resistance Distal nephron Vasopressin release from posterior pituitary Arterioles Volume H 2 O reabsorption + + H 2 O intake Thirst + + Volume conserved DEHYDRATION CARDIOVASCULAR MECHANISMS RENIN-ANGIOTENSIN SYSTEM RENAL MECHANISMS HYPOTHALAMIC MECHANISMS Carotid and aortic baroreceptors Hypothalamic osmoreceptors Osmolarity and Blood pressure Granular cells GFR Flow at macula densa Angiotensinogen ANG I ACE ANG II Aldosterone Na + reabsorption Distal nephron + Hypothalamus Adrenal cortex Atrial volume receptors; Carotid and aortic baroreceptors Renin

11 Acid-Base Balance Normal pH of plasma is 7.38–7.42 H + concentration is closely regulated Changes can alter tertiary structure of proteins Abnormal pH affects the nervous system Acidosis: neurons become less excitable and CNS depression Alkalosis: hyperexcitable pH disturbances Associated with K + disturbances

12 Acid-Base Balance Hydrogen ion and pH balance in the body Figure Fatty acids Amino acids CO 2 (+ H 2 O) Lactic acid Ketoacids CO 2 (+ H 2 O) H + input H + output Plasma pH 7.38–7.42 Buffers: HCO 3 – in extracellular fluid Proteins, hemoglobin, phosphates in cells Phosphates, ammonia in urine H+H+

13 Acid and Base Input Acid Organic acids Diet and intermediates Under extraordinary conditions Metabolic organic acid production can increase Ketoacids Diabetes Production of CO 2 Acid production Base Few dietary sources of bases

14 pH Homeostasis Buffers Moderate changes in pH Combines with or releases H + Cellular proteins, phosphate ions, and hemoglobin Ventilation Rapid response 75% of disturbances Renal regulation Slowest of the three mechanisms Directly excreting or reabsorbing H + Indirectly by change in the rate at which HCO 3 – buffer is reabsorbed or excreted

15 pH Disturbances The reflex pathway for respiratory compensation of metabolic acidosis Figure Respiratory control centers in the medulla Plasma H + ( pH) Plasma P CO 2 Carotid and aortic chemoreceptors Central chemoreceptors Plasma P CO 2 Plasma H + ( pH) by Law of Mass Action Action potentials in somatic motor neurons Muscles of ventilation Rate and depth of breathing Negative feedback Sensory neuron Interneuron

16 pH Disturbances Overview of renal compensation for acidosis Figure CO 2 + H 2 O Carbonic Anhydrase Nephron cells Acidosis pH = H + HCO 3 – reabsorbed HCO 3 – buffer added to extracellular fluid Amino acids + H + NH 4 + H + + HCO 3 – H + secreted H+H+ HPO 4 2– filtered H 2 PO 4 – Excreted in urine Blood

17 Renal Compensation: Transporters Apical Na + -H + exchanger (NHE) Basolateral Na + -HCO 3 – symport H + -ATPase H + -K + -ATPase Na + -NH 4 + antiport

18 Renal Compensation Proximal tubule H + secretion and the reabsorption of filtered HCO 3 – Figure Na + -H + antiport secretes H +. H + in filtrate combines with filtered HCO 3 – to form CO 2. CO 2 diffuses into cell and combines with water to form H + and HCO 3 –. H + is secreted again and excreted. HCO 3 – is reabsorbed. Glutamine is metabolized to ammonium ion and HCO 3 –. NH 4 + is secreted and excreted. HCO 3 – is reabsorbed. Peritubular capillary Interstitial fluid Reabsorbed Filtration Glomerulus HCO 3 – H + + HCO 3 – HCO 3 – CO 2 + H 2 O Na + Secreted H + Na + H + Na + HCO 3 – Na + Bowman’s capsule H 2 O + CO 2 Filtered HCO 3 – + H + Na + CA Na +  KG HCO 3 – Glutamine NH 4 + HCO 3 – Secreted H + and NH 4 + will be excreted Proximal tubule cell

19 Intercalated Cells Type A intercalated cells function in acidosis Figure 20-22a

20 Intercalated Cells Type B intercalated cells function in alkalosis Figure 20-22b

21 Acid-Base Balance Table 20-2

22 Summary Fluid and electrolyte homeostasis Water balance Vasopressin, aquaporin, osmoreceptors, countercurrent multiplier, and vasa recta Sodium balance Aldosterone, principal cells, ANG I and II, renin, angiotensinogen, ACE, and ANP Potassium balance Hyperkalemia and hypokalemia

23 Summary Behavioral mechanisms Integrated control of volume and osmolarity Acid-base balance Buffers, ventilation, and kidney Acidosis and alkalosis Intercalated cells


Download ppt "Chapter 20b Integrative Physiology II: Fluid and Electrolyte Balance."

Similar presentations


Ads by Google