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Fluid, Electrolyte, and Acid-Base Balance

Terms in this set (24)

What are the components and approximate %'s that make up the human body?
Water- 45-75%
Fat mass- 10-25% males; 18-32% females
Lean body mass- 10-30%
ICF
intercellular fluid volume: 25L, 40% of the body weight
(water and electrolytes)
ECF
extracellular fluid volume: 15L, 20 % of body weight
-Interstitial fluid volume: 12 L, 80% of ECF
- Plasma Volume: 3L, 20% of ECF
What is fluid balance?
a state of equilibrium in which the amount of fluid consumed equals the amount lost in urine, feces, and exhaled water vapor
How do we gain water?
- Drinking water (1000 ml)
-Water content in food (1000 ml)
- water produced from metabolism (350 ml)
How do we lose water?
- Skin perspiration (500 ml)
- lung respiration (400 ml)
- Urine (1300 ml)
- feces (150 ml)
What role does the hypothalamus play in balancing hydration?
it monitors the amount of water in the body by sensing the concentration of electrolytes in the blood
What is the role of ADH in balancing hydration?
It is produced by the hypothalamus & released by the posterior pituitary, causes more water to be retained by the kidneys when water levels are low

- effects water retention by creating special channels for water, called aquaporins, inside the kidneys so that more water can be resorbed before it is excreted
what is the role of aldosterone in balancing hydration?
- produced by the adrenal cortex
- causes the retention of water in the body by increasing the levels of sodium and potassium which cause the body to resorb more water
Dehydration:
Loss of 1-3%
mouth dryness, fatigue, dizziness, and heat cramps
Dehydration:
Loss of 4-7%
heat exhaustion- muscle cramps, mental confusion, elevated heart rate, and cool skin
Dehydration:
loss of 8-10%
heat (sun) stroke- internal temp rises dangerously, hot dry skin, loss of consciousness, medical attention necessary
Dehydration:
loss of >10%
renal and CV failure -> death
How does Hyperhydration develop?
- excessive intake of water

- intake w/o sodium, chloride, or potassium

- during prolonged low intensity activities results in diluted blood electrolytes levels which affect heart rate and contractile force
what is the major concern with hyperhydration?
excessive hyper hydration may result in hypertremia, pulmonary and or cerebral edema
what are electrolytes?
salts, acids, and bases
What are the functions of electrolytes?
- neuromuscular excitability
- metabolic pathways
- membrane potential
- controlling fluid movements
Sodium
Functions:
- membrane potential and depolarization
- contransport and other solutes
Changes in plasma sodium levels affect:
- plasma volume, BP
- ICF and interstitial fluid volumes
Potassium
- aldosterone stimulates potassium ion secretion by principal cells
- in cortical collecting ducts, for each sodium resorbed, a potassium secreted
- potassium controls its own ECF concentration via feedback regulation of aldosterone release
- increased k+ in the ECF around the adrenal cortex causes release of aldosterone and K+ secretion
Calcium
- most abundant mineral, 99% found in bone and teeth
- in ECF it is important for blood clotting and muscle cell contraction
Hypercalcemia
increases excitability, causes increased heart rates, muscle spasms, and muscle tetany
Hypocalcemia
inhibits neurons and muscle cells, may cause heart arrhythmias and calcification of soft tissues if severe
Acidosis
occurs when blood pH falls below 7.35
can be due to:
- increased acid production within the body
- decreased acid excretion
- increased excretion of base
Alkalosis
occurs when blood pH rises above 7.45
can be due to:
- electrolyte disturbances- throwing up, severe dehydration
- consumption of base
- hyperventilation
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