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Water, Electrolytes, and

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Presentation on theme: "Water, Electrolytes, and"— Presentation transcript:

1 Water, Electrolytes, and
Acid-Base Balance

2 Body Fluids Intracellular Extracellular
All fluids inside cells of body About 40% of total body weight Extracellular All fluids outside cells About 20% of total body weight Subcompartments Interstitial fluid and plasma; lymph, CSF, synovial fluid

3 Body Fluid Compartments

4 Water Content Regulation
Sources of water Ingestion Cellular metabolism Routes of water loss Urine Evaporation Perspiration Respiratory passages Feces Content regulated so total volume of water in body remains constant Kidneys primary regulator of water excretion Regulation processes Osmosis Osmolality Baroreceptors Learned behavior

5 Extracellular Fluid Osmolality
Adding or removing water from a solution changes this Increased osmolality Triggers thirst and ADH secretion Decreased osmolality Inhibits thirst and ADH secretion

6 Hormonal Regulation of Blood Osmolality

7 Regulation of ECF Volume
Increased ECF results in Decreased aldosterone secretion Increased ANH secretion Decreased ADH secretion Decreased sympathetic stimulation Decreased ECF results in Increased aldosterone secretion Decreased ANH secretion Increased ADH secretion Increased sympathetic stimulation Mechanisms Neural Renin-angiotensin-aldosterone Atrial natriuretic hormone (ANH) Antidiuretic hormone (ADH)

8 Hormonal Regulation of Blood Volume

9 Hormonal Regulation of Blood Volume

10 Regulation of ECF Volume

11 Regulation of ICF and ECF

12 Regulation of Electrolytes in ECF
Na+ Ions Dominant ECF cations Responsible for 90-95% of osmotic pressure Regulation of Na+ ions Kidneys major route of excretion Small quantities lost in sweat Terms Hypernatremia Hyponatremia Electrolytes Molecules or ions with an electrical charge Water ingestion adds electrolytes to body Kidneys, liver, skin, lungs remove from body Concentration changes only when growing, gaining or losing weight

13 Mechanisms Regulating Blood Sodium

14 Mechanisms Regulating Blood Sodium

15 Abnormal Plasma Levels of Sodium Ions

16 Regulation of Chloride, Potassium, Magnesium Ions
Potassium ions Maintained in narrow range Affect resting membrane potentials Aldosterone increases amount secreted Terms Hyperkalemia Hypokalemia Chloride ions Predominant anions in ECF Magnesium ions Capacity of kidney to reabsorb is limited Excess lost in urine Decreased extracellular magnesium results in greater degree of reabsorption

17 Potassium Ion Regulation in ECF

18 Abnormal Concentration of Potassium Ions

19 Abnormal Plasma Levels of Magnesium Ions

20 Regulation of Blood Magnesium

21 Regulation of Calcium Ions
PTH increases Ca2+ extracellular levels and decreases extracellular phosphate levels Vitamin D stimulates Ca2+ uptake in intestines Calcitonin decreases extracellular Ca2+ levels Regulated within narrow range Elevated extracellular levels prevent membrane depolarization Decreased levels lead to spontaneous action potential generation Terms Hypocalcemia Hypercalcemia

22 Regulation of Calcium Ions

23 Regulation of Phosphate Ions
Under normal conditions, reabsorption of phosphate occurs at maximum rate in the nephron An increase in plasma phosphate increases amount of phosphate in nephron beyond that which can be reabsorbed; excess is lost in urine

24 Regulation of Blood Phosphate

25 Acids and Bases and Buffers
Buffers: Resist changes in pH When H+ added, buffer removes When H+ removed, buffer replaces Types of buffer systems Carbonic acid/bicarbonate Protein Phosphate Acids Release H+ into solution Bases Remove H+ from solution Acids and bases Grouped as strong or weak

26 Regulation of Acid-Base Balance

27 Regulation of Acid-Base Balance

28 Buffer Systems

29 Respiratory Regulation of Acid-Base Balance
Respiratory regulation of pH is achieved through carbonic acid/bicarbonate buffer system As carbon dioxide levels increase, pH decreases As carbon dioxide levels decrease, pH increases Carbon dioxide levels and pH affect respiratory centers Hypoventilation increases blood carbon dioxide levels Hyperventilation decreases blood carbon dioxide levels

30 Respiratory Regulation of Acid-Base Balance

31 Renal Regulation of Acid-Base Balance
Secretion of H+ into filtrate and reabsorption of HCO3- into ECF cause extracellular pH to increase HCO3- in filtrate reabsorbed Rate of H+ secretion increases as body fluid pH decreases or as aldosterone levels increase Secretion of H+ inhibited when urine pH falls below 4.5

32 Kidney Regulation of Acid-Base Balance

33 Hydrogen Ion Buffering

34 Acidosis and Alkalosis
Acidosis: pH body fluids below 7.35 Respiratory: Caused by inadequate ventilation Metabolic: Results from all conditions other than respiratory that decrease pH Alkalosis: pH body fluids above 7.45 Respiratory: Caused by hyperventilation Metabolic: Results from all conditions other than respiratory that increase pH Compensatory mechanisms

35 Acidosis and Alkalosis

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