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25 Cards in this Set
- Front
- Back
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Dehydration
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Increased blood osmolarity and decreased blood volume and BP
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Thirst Mechanisms
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Stimulation of thirst center (in hypothalamus)
1.) Angiottensin 2 produced in response to decreased blood pressure 2.) ADH produced in response to increased blood osmolarity 3.) Hypothalamic somoreceptors: signal in response to increased ECF osmolarity |
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Inhibition of Salivation
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Thirst center sends SYMPATHETIC signals to salivary glands
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Regulation of Output
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- Controlling Na+ re absorption (changes volume)
- as Na+ is re absorbed or excreted, water follows |
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Action of ADH in output
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- Changes the concentration of urine
- ADH secretion (as well as thirst center) stimulated by hypothalamic osmoreceptors in response to dehydration - 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 (decreases) in water volume and increases osmolarity |
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Hypovolemia
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Volume depletion, total body water decreases, osmolarity is normal
hemorrhage, severe burns, chronic vomiting or diarrhea |
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Dehydration
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Total body water decreases,
osmolarity rises Due to: lack of drinking water, diabetes, profuse sweating, diuretics |
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Infants are more vulnerable to dehydration because
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Their high metabolic rate demands high urine excretion, kidneys cannot concentrate urine effectively, greater ratio of body surface to mass
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Most serious effects of dehydration
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circulatory shock, neurological dysfunction, infant mortality
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Excess fluid leads to
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Pulmonary and cerebral edema
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Hypotonic Hydration
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More water than sodium retained or engested, ECF hypotonic, can cause cellular swelling (RBCs) - like drinking too much pure water can be bad for you
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Potassium Homeostasis
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Aldosterone stimulates renal secretion of K+ and reabsorbs Na+
Potassium and sodium always move in opposite ways |
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Hypercalcemia is caused by
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Alkalosis
Hyperparathyroidism Hypothyroidism |
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Hypercalcemia
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Decreased Na+ permeability in the membrane, inhibits depolarization
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What does Hypercalcemia do to the body?
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Concentrations greater than 12 mEq/L cause: muscular weakness, depressed reflexes, cardiac arrhythmias
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Hypocalcemia is caused by
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Low levels of Vitamin D
diarrhea Pregnancy Acidosis Lactation Hypoparathyroidism Hyperthyroidism |
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Hypocalcemia
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Increased Na+ permeability causing nervous and muscular systems to be abnormally excitable
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What does hypocalcemia do to the body?
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Causes: Tetanus
larygnospasm Death |
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Acid-Base balance of Urine
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Urine is slightly acidic, variable in how much H+ can be released in the urine, gets rid of excess acidosis?
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Acidosis
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H+ diffuses into the cells and drives out K+, elevating K+ in the ECF
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What does acidosis do to the cells?
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H+ buffered by protein in the ICF causes membrane hyperpolarization, nerve and muscle cells become harder to stimulate
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What are the risks of Acidosis?
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CNS depression may lead to death
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Alkalosis
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H+ diffuses out of the cell and K+ diffuses in.
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What does alkalosis do to the cells?
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Membrane is depolarized, nerves overstimulate
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What are the risks of Alkalosis?
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Spasms, tetany, convulsions, respiratory paralysis
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