chapter-24-water-electrolyte-and-acid-base-balance.pdf - Chapter 24 Water Electrolyte and Acid-Base Balance 24-1 Water Electrolyte and Acid-Base Balance

chapter-24-water-electrolyte-and-acid-base-balance.pdf -...

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24-1 Chapter 24: Water, Electrolyte, and Acid-Base Balance
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24-2 Water, Electrolyte and Acid-Base Balance
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24-3 Water Balance Total body water for 150 lb. male = 40L Fluid compartments 65% intracellular fluid 35% extracellular fluid 25% tissue fluid 8% blood plasma, lymph 2% transcellular fluid (CSF, synovial fluid)
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24-4 Water Movement in Fluid CompartmentsElectrolytes play principle role in water distribution and total water content
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24-5 Water Gain Preformed water ingested in food and drink Metabolic water by-product of aerobic metabolism and dehydration synthesis
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24-6 Water Loss Routes of loss urine, feces, expired breath, sweat, cutaneous transpiration Loss varies greatly with environment and activity respiratory loss : with cold, dry air or heavy work perspiration loss : with hot, humid air or heavy work Insensible water loss breath and cutaneous transpiration Obligatory water loss breath, cutaneous transpiration, sweat, feces, minimum urine output (400 ml/day)
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24-7 Fluid Balance
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24-8 Regulation of Fluid Intake Dehydration blood volume and pressure blood osmolarity Thirst mechanisms stimulation of thirst center (in hypothalamus) angiotensin II: produced in response to BP ADH: produced in response to blood osmolarity hypothalamic osmoreceptors: signal in response to ECF osmolarity inhibition of salivation thirst center sends sympathetic signals to salivary glands
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24-9 Satiation Mechanisms Short term (30 to 45 min), fast acting cooling and moistening of mouth distension of stomach and intestine Long term inhibition of thirst rehydration of blood (blood osmolarity) stops osmoreceptor response, capillary filtration, saliva
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24-10 Dehydration, Thirst, and Rehydration
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24-11 Regulation of Output Controlling Na+reabsorption (changes volume) as Na+is reabsorbed or excreted, water follows Action of antidiuretic hormone (ADH)(changesconcentrationofurine) ADH secretion (as well as thirst center)stimulated by hypothalamic osmoreceptors in responsetodehydration aquaporins synthesized in response to ADH membrane proteins in renal collecting ducts to channel water back into renal medulla, Na+is still excreted effects: slows in water volume andosmolarity
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24-12 Secretion and Effects of ADH
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24-13 Disorders of Water Balance Fluid deficiency volume depletion (hypovolemia) total body water , osmolarity normal hemorrhage, severe burns, chronic vomiting or diarrhea dehydration total body water , osmolarity rises lack of drinking water, diabetes, profuse sweating, diuretics infants more vulnerable high metabolic rate demands high urine excretion, kidneys cannot concentrate urine effectively, greater ratio of body surface to mass affects all fluid compartments most serious effects circulatory shock, neurological dysfunction, infant mortality
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24-14 Water Loss & Fluid Balance
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