Hypotonic hydration more water than Na retained or ingested ECF hypotonic can

Hypotonic hydration more water than na retained or

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Hypotonic hydration more water than Na + retained or ingested, ECF hypotonic - can cause cellular swelling Most serious effects are pulmonary and cerebral edema Blood Volume & Fluid Intake Kidneys compensate very well for excessive fluid intake, but not for inadequate intake Fluid Sequestration Excess fluid in a particular location Most common form: edema accumulation in the interstitial spaces Hematomas hemorrhage into tissues; blood is lost to circulation Pleural effusions several liters of fluid may accumulate in some lung infections Clicker Question: So you probably know that hot weather can lead to water loss and dehydration, but did you know that cold weather is a threat to water balance? Which would be a major factor contributing to cold weather dehydration? A. Profuse sweating B. Constriction of blood vessels to the skin C. Drinking hot tea D. Increased body surface-to-volume ratio E. Increased release of ADH Electrolytes Chemically reactive in metabolism, determine cell membrane potentials, osmolarity of body fluids, water content and distribution
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Major cations Na + , K + , Ca 2+ , H + Major anions Cl - , HCO 3 - , PO 4 3- Sodium - Functions Membrane potentials Accounts for 90 - 95% of osmolarity of ECF Na+-K+ pump (exchanges intracellular Na + for extracellular K + ) cotransport of other solutes (glucose) generates heat NaHCO 3 (sodium bicarbonate) has major role in buffering pH Sodium - Homeostasis Deficiency rare 0.5 g/day needed, typical diet has 3 to 7 g/day Aldosterone - salt retaining" hormone” primary effects: decrease NaCl and increase K + excreted in urine ADH - raise blood Na + levels stimulate ADH release kidneys reabsorb more water (without retaining more Na + ) ANF (atrial natriuretic factor) released with increase BP kidneys excrete more Na + and water, thus decrease BP Others - estrogen retains water during pregnancy progesterone has diuretic effect Sodium Imbalances Hypernatremia plasma sodium > 145 mEq/L o from IV saline water retention, hypertension and edema Hyponatremia plasma sodium < 130 mEq/L result of excess body water, quickly corrected by excretion of excess water Potassium - Functions
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Most abundant cation of ICF Determines intracellular osmolarity Membrane potentials (with sodium) Na + -K + pump Potassium - Homeostasis 90% of K + in glomerular filtrate is reabsorbed by the PCT DCT and cortical portion of collecting duct secrete K + in response to blood levels Aldosterone stimulates renal secretion of K + Potassium - Imbalances Most dangerous imbalances of electrolytes Hyperkalemia - effects depend on rate of imbalance if concentration rises quickly, (crush injury) the sudden increase in extracellular K + makes nerve and muscle cells abnormally excitable slow onset, inactivates voltage-gated Na + channels, nerve and muscle cells become less excitable Hypokalemia sweating, chronic vomiting or diarrhea, laxatives nerve and muscle cells less excitable o muscle weakness, loss of muscle tone, decrease reflexes, arrthymias Chloride - Functions ECF osmolarity most abundant anions in ECF Stomach acid required in formation of HCl Chloride shift CO 2 loading and unloading in RBC’s pH major role in regulating pH
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  • Fall '19
  • pH, ICF, ECF, Bicarbonate

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