Ch 26 Electrolytes Flashcards
electrolytes
- ions or molecules that have an electric charge
- carry an electric current
- Na+, K+, H+, HCO3-
osmolarity
concentration of molecules/ions per VOLUME of solution (mOsm/Liter)
osmolality
concentration of molecules/ions per WEIGHT of solution (mOsm/Kg)
milliequivalent per liter
mEq/L
number of electrical charges in one liter of body fluid
intracellular fluid = ICF
- 2/3 of body fluid
- K+, Mg2+, SO4^2-, HPO4^2-, H2PO4-, PO4^3-
extracellular fluid = ECF
- 1/3 of body fluid
- Na+, Cl-, Ca2+, HCO3-
who plays a primary role in distribution of water and total fluid content of the body?
Electrolytes
Fluid INTAKE is regulated primarily by hypothalamic thirst center. What stimulates it?
- dry mouth
- increased angiotensin II
- increased blood osmolarity picked up by central osmoreceptors in hypothalamus
- this increases fluid intake
regulation of water loss
- determined primarily by the kidney
- under regulation of many hormones; ADH, aldosterone, Angiotensin II, ANP
- minimum of 500 mL excreted/day to flush out urine solutes
Volume depletion(fluid deficiency) = hypovolemia
- same amount of water and electrolytes are lost without replacement
- fluid osmolality remains fairly normal
- occurs with; hemorrhage, surgical losses, severe GI loss, severe burns, hyposecretion of aldosterone, some diuretics
Dehydration(fluid deficiency)
- body loses more water than electrolytes
- fluid osmolality goes up
- causes; decreased ingestion of fluid, excessive sweating, heavy respirations, excessive urination(diabetes mellitus, ketonuria, some diuretics, alcohol intake, diabetes insipidus)
Volume excess(fluid overload)
- both water and electrolytes are retained = hypervolemia
- causes; too much aldosterone, too much cortisol, renal failure, excessive IV fluids, medication side effects, heart failure
Hypotonic hydration(fluid overload)
- more water than sodium is retained, or you lose water plus electrolytes but replace only with plain water
- ECF becomes hypotonic
- causes; drinking H2O to replace isotonic losses, SIADH, severe CHF or renal insufficiency, psychogenic polydipsia
Fluid sequestration
- fluid accumulates in a particular location
- causes; edema, internal hemorrhage, pleural effusion, ascites, vascular shock
sodium
MOST ABUNDANT cation in ECF
- normal: ~140 mEq/L
- hyponatremia: 145 mEq/L
- regulation: aldosterone, angiotensin II, ANP, estrogen, progesterone, epinephrine, norepinephrine
