13: hydration

what is euhydration

adequate water volume to meet demands

what is hyperhydration

excess amount of water

what is hypohydration

insufficient water volume

what is dehydration

process of losing water

what is rehydration

process of gaining water

what is hypovolemia

gradual loss of volume → decreased blood flow to skin and working muscle, increased risk of hyperthermia

what is ICF and how much of the total body water is it

intracellular fluid, water within cells, 2/3

what is ECF and how much of the total body water is it

extracellular fluid, water outside cells, 1/3

what are the components of ECF and what do they do

plasma: transportation and thermo regulation

interstitial fluid: between cells, lymph system carries water back to blood

what is hydrostatic pressure

difference in fluid pressure

ex. edema from pressure via gravitational pull

what is osmotic pressure

tendency for water to move from low to high solue concentrauion

what happens in cells when sweat occurs

plasma reduced, sodium increased, water leaves

differences in composition of ECF and ICF

ECF: high Na⁺, Cl^-, HCO₃^-

ICF: high K⁺, protein^-, PO₄^3-

process of fluid regulation

blood volume decreases, osmotic pressure increases → ADH secreted → lower volume and higher concentrated urine → blood volume increases, osmotic pressure decreases

what stimulates thirst when hypohydrated

increased osmotic pressure

adequate intake of water for males and females

male: 15 cups/day

female: 11 cups/day

how to calculate AI for water in children/young adults

1.5 x bodyweight(.45)

how to calculate AI for water in older adults

1.1 x bodyweight(.45)

sources of endogenous addition of water to body

metabolism - byproduct of anaerobic reactions

adds around 350ml/day

sources of exogenous addition of water to body

drink, food (20-25%)

what are insensible avenues of water loss

hard to account for - ventilation, through skin

what are sensible avenues of water loss

more easily measured - feces, urine, sweat

what are the hydration recommendations for physical activity

4-8oz consumed every 15-20 minutes of exercise

prehydration: start PA euhydrated with normal plasma electrolyte levels

hydration during exercise: prevent excessive dehydration and changes in electrolyte balance

posthydration: fully replace any fluid and electrolytes lost

what is the main challenge to fluid balance during PA

thermoregulation - heat stress and exercise stress combined

what is the process that can lead to hypovolemia

exercise → increased core temp → increased sweat rates → hypovolemia

how does 1, 2, and 3% body weight dehydration affect performance

1: thirst

2: thirst, discomfort, loss of appetite, begin impaired performance

>3: disturb physiological function, increased risk of heat illness, significant impairment of performance

what are the components of abnormal thermoregulatory capabilities

muscle cramps, heat exhaustion, heat stroke

signs of heat exhaustion

dizziness, nausea, weakness

signs of heat stroke

confusion, loss of consciousness w

what factors influence thermoregulation

body size, gender, age, body comp

describe the effect body composition has on thermoregulation

more muscle mass, more water

more fat mass, less water, harder for heat to dissipate

ways to rehydrate

beverages: fluid replacers, carb loading drinks, nutrient supplement drinks

water, black coffee, tea, sports drinks, fruit juice, milk

what is hyponatremia

hyperhydration → increased Na loss via sweat → increase cell swelling → nerves swell, malfunction, die

clean water access

85% US gets water from public water systems, mortality rate from waterborne illness dropped - public health achievement

still issues in other countries