BI 233 Fluid Balance Test

Total body water varies with what conditions

Age, gender, adiposity

Do men or women have higher body water content?

Men

Do young people or elderly have higher body water content?

Young people

Does body water content increase or decrease with obesity

Decrease, how much varies with body fat percentage, can be as low as 30-40% of body weight

Total body water accounts for how much of body weight

60%

How much of total body water is intracellular, and how much is extracellular

40%, 20%

intracellular fluid volume is

the fluid within the cell, accounts for 40% body weight

extracellular fluid volume is

fluid outside the cell, accounts for 20% body weight consists of interstitial fluid volume and plasma fluid volume

interstitial fluid volume is

fluid in spaces between cells, 80% of ECF

plasma fluid volume is

fluid portion of the blood within the vessels, 20% of ECF

how is water lost (part of maintaining water balance)

excretion, respiration, evaporation, and defecation

how is water replaced (part of maintaining water balance)

ingestion and metabolism

What are the signals governing thirst

increased plasma osmolality, hypovolemia, dryness of throat and mouth

tonicity

how a solution will affect cell volume - i.e. hypertonic, isotonic, hypertonic

(tonikos: pertaining to stretching)

Can you have an iso-osmotic solution that is not isotonic

yes

fluid shifts are what

involve disorders of sodium and water imbalance

iso-osmotic fluid shift results in changes in what

the ECF

hyperosmotic or hypo-osmotic fluid shifts result in changes in what

the ICF

proportionate loss of both H2O and Na+ results in what

isotonic fluid volume deficit → characterized by a decrease in the ECF and leads to decreased circulatory function and decreased urine output

proportionate gain of both H2O and Na+ results in what

isotonic fluid volume expansion → characterized by increase of fluids in the ECF and leads to increased vascular volume and edema

hypertonic and hypotonic changes exert effects on what

ICF

hypernatremia does what to water and cells

draws water from ICF into ECF, cells shrink

hyponatremia does what to water and cells

water pulled from ECF into ICF, cells swell

fluid volume deficit

characterized by decrease in extracellular fluid volume