Ch. 26 LEC - Fluid, Electrolyte, Acid-Base Balance

Lecture Exam 5

the typical body water content of adult males is _% water

60

the typical body water content of adult females is _% water

50

why is the average body water content in adult females less than that of males?

females have higher fat content and less skeletal muscle mass

body water content declines to _% in old age

45

the typical body water content of infants is _% water or more

73

why is the average body water content in infants greater than that of adults?

infants have low body fat and low bone mass

define intracellular fluid (ICF)

fluid located inside tissue cells

define extracellular fluid (ECF)

fluid located outside of cells

define interstitial fluid (IF)

a sub-compartment of the ECF, this is the fluid found specifically in the spaces between cells

The total body water content is about [NUMBER] L. ICF makes up [FRACTION] ([NUMBER] L) while the ECF makes up [FRACTION] ([NUMBER] L) of the body water content. Of the 15 liters of ECF, [NUMBER] L is plasma and [NUMBER] L is interstitial fluid. The rest of the ECF is composed of lymph, CSF, humors of the eye, synovial fluid, serous fluid, and GI secretions

40, 2/3, 25, 1/3, 15, 3, 12

water is the universal [SOLUTE/SOLVENT/SOLUTION]

solvent

the 2 main classes of solutes in bodily fluids are _ and _

electrolytes, nonelectrolytes

characterize nonelectrolytes and provide examples

mostly organic substances that do not dissociate in water (e.g., glucose, lipids, creatinine, urea)

characterize electrolytes and provide examples

the most numerous solutes in the body and can dissociate into ions in water (e.g., inorganic salts, all acids and bases, some proteins)

identify the reason electrolytes are crucial to the body

• have great osmotic power → contributes to fluid shifts

• determine chemical and physical reactions of fluids

name the major cation(s) and anion(s) of the ECF

• cation: Na+

• anion: Cl-

name the major cation(s) and anion(s) of the ICF

• cation: K+

• anion: HPO4 2-

fluid movement among compartments (ECF, ICF) is regulated by__ and __ pressures

osmotic, hydrostatic

what element is central to water regulation?

Na+

list the possible sources of water intake

beverages, food, metabolic water

list the possible sources of water output

urine, insensible water loss (skin and lungs), perspiration, feces

true/false: the amount of water intake is usually higher than water output

false - the amount of water intake is usually equal to water output

water intake = water output = [NUMBER] mL/day

2500

the neurological driving force for water intake is the _

hypothalamic thirst center

list the factors that stimulate the osmoreceptors of the hypothalamic thirst center

• high plasma osmolality (2-3%)

• angiotensin II

• dry mouth

• substantial decrease in blood volume or pressure

low osmolality ([LOW/HIGH] water/[LOW/HIGH] particles → thirst center is [INHIBITED/ACTIVATED] → [YES/NO] thirst

high, low, inhibited, no

high osmolality ([LOW/HIGH] water/[LOW/HIGH] particles → thirst center is [INHIBITED/ACTIVATED] → [YES/NO] thirst

low, high, activated, yes

water intake:

• drinking water creates [INHIBITION/ACTIVATION] of the thirst center

• [INHIBITORY/ACTIVATORY] feedback signals include:

  • relief of [DRY/WET] mouth

  • activation of stomach and intestinal [CONSTRICTING/STRETCHING] receptors

inhibition, inhibitory, dry, stretching