1. Body Fluids Flashcards
(38 cards)
Homeostasis
relative constancy of Milieu Intérieur
Body water percentage (PRI)
60%
Physiological Reference Individual (PRI)
21 yo white male 70kg
Body water varies with
sex, age and body fat
Body water of newborn
75%
Body water after puberty
women = 50%
men = 60%
Body water over 65yo
women = 45%
men = 50%
Calculating absolute body water
(weight(kg) x body water(%))/100
Water balance
input = output
Water input
- oral fluid
- oral intake as food
- oxidative water from metabolism
Water output
- breathing (lungs)
- passive evaporation (skin)
- urine (kidneys)
- stool
- facultative loss
Obligatory loss
will always be lost no matter the input, can be insensible or sensible
Insensible loss
can’t feel it: breathing + passive evaporation loss
Sensible loss
aware: urine + stool
Facultative loss
vary with intake but necessary to maintain balance
Insensible perspiration key points
- pure water
- passive evaporation
- entire skin surface (no sweat glands needed)
- continuous and obligatory
Sweating key points
- electrolyte solution
- active secretion
- involves sweat glands
- activated by heavy work/temp
Negative water balance
water loss greater than water intake
Causes of negative water balance (5)
- reduced intake
- excessive loss from gut
- excessive sweating
- excessive loss in expired air
- excessive loss in urine
Positive water balance (water intoxication)
water loss smaller than water intake
Causes of positive water balance
- excessive intake
- renal system failure
2 major body water compartments and distribution
Intracellular Fluid (ICF) = 2/3, 40%
Extracellular Fluid (ECF) = 1/3, 20%
Components of Extracellular Fluid
- plasma = 5%
- Interstitial Fluid (ISF) = 15%
- lymph
- transcellular fluid
Hematocrit (Ht)
percentage of blood volume occupied by red blood cells