fluid, electrolyte, acid-base balance Flashcards
3 types of homeostatic balance:
fluid balance, electrolyte and acid-base balance
major fluid compartments of the body
65% intracellular fluid
35% extracellular fluid
water moves easily through __, osmotic gradients never last long
membranes
if __ of the tissue fluid rises, water moves out of the cell
osmolarity
if osmolarity of the tissue fluid falls, __
water moves in the cell
sodium salts in
ECF
potassium salts in
ICF
plays the role of governing the bodys water distribution and total water content
electrolytes
bodys two sources of water
preformed and metabolic water
water ingested in food and drink
preformed water (2,300 mL/day)
water formed by aerobic metabolism and dehydration synthesis
metabolic water (200 mL/day)
sensible water loss is observable:
urine, feces, sweat
insensible water loss is unnoticed:
expired breath, cutaneous transportation
water output that is unavoidable
obligatory water loss:
expired air, cutaneous transportation, sweat, fecal moisture, and minimum urine output
hypothalamic osmoreceptors produce signals in response to increased ECF osmolarity, antidiuretic hormone is produced
regulating water intake
only way to control water output is through variation in __
urine volume
cannot replace water or electrolytes
kidneys
water output is slowed through action of
ADH
ADH secretion is triggered by hypothalamic osmoreceptors in response to
dehydration (water output)
in water output, __ are synthesized in response to ADH
aquaporins
important for electrical signaling in nerve and muscle cells, sodium ions bound to the proteoglycans of cartilage retain water
sodium
principal cation in ECF
sodium (Na+)
source of energy for cotransport of other solutes
sodium
generates body heat, major role of buffering pH in ECF
sodium
adult needs how much sodium per day
0.5 g
typical american diet contains how much sodium per day
3 to 7 g
kidneys reabsorb almost
no sodium
urine contains up to
30 g of sodium per day
natriuretic peptides inhibit
sodium reabsorption
plasma sodium concentration greater than 145 mEq/L, causes water retension, hypertension, and edema
hypernatremia
plasma sodium concentration less than 130 mEq/L, person loses large volumes of sweat or urine, replacing it with drinking water
hyponatremia
electrical signaling in nerve and muscle cells, responsible for resting membrane potential and repolarization and hyperpolarization of the action potential
potassium
most abundant cation of ICF
potassium
greatest determinant of intracellular osmolarity and cells volume
potassium
important for thermogenesis
Na+-K+ pump
90% of potassium in glomerular filtrate is reabsorbed by PCT, rest is excreted in
urine
stimulates renal secretion of K+
aldosterone
most dangerous types of electrolyte imbalances
potassium imbalances
plasma potassium concentration above 5.5 mEq/L, can produve cardiac arrest, nerve and muscle cells become less excitable
hyperkalemia
plasma potassium concentration less than 3.5 mEq/L, loss of muscle tone, decreased reflexes, and arrhythmias
hypokalemia
most abundant anion in ECF, major contribution to ECF osmolarity
chloride, CL-
required for the formation of stomach acid, accompanies C)2 loading and unloading in RBCs
chloride
major role in regulating body pH
chloride
as sodium is retained, __ ions follow
chloride
chloride imbalances disturb
acid base balance
result of dietary excess or administration of IV saline
hyperchloremia of chloride