ch 7 - water and electrolytes Flashcards
what is the most important nutrient
water
60% of adult body weight is
water
fluid balance
considers water volume and solute concentration
euhydration
adequate water to meet physiological demands
hyperhydration
excess water, considered temporary
hypohydration
insufficient water volume
dehydration
process of the body losing water volume
electrolytes involved in fluid balance: cations
- sodium
- potassium
- calcium
- magnesium
electrolytes involved in fluid balance: anions
- chloride
- bicarbonate
- phosphate
- protein
body water components
ECF + ICF
components of ECF
- plasma
- interstitial fluid
two thirds of body water is found in the
ICF
main component of ECF
interstitial fluid
water moves from an area of ____ solute concentration to an area of ____ solute concentration
lower; higher
which two are similar in the composition and distribution of electrolytes
plasma and interstitial
isotonicity
the concentration of all solutes is the same on both sides of the cell membrane, so there is no net movement of water
hypertonicity
the concentration of all solutes is greater outside than inside the cell, so water moves out of the cell, causing the cell to shrink
hypotonicity
the concentration of all solutes is less outside than inside the cell, so water moves into the cell, causing it to swell
sensible water loss
- feces
- urine
- sweat
osmosis water loss
- avenues of loss that are not normally noticed
- ventilation and inhaled air
- nonsweat diffusion through the skin
Adults in the United States consume approximately ________percent of their total daily water intake via food and ________ percent from tap or bottled water.
20 to 25; 30 to 35
the body is said to be in fluid balance if
a sufficient amount of fluid is present that allows for the body to function normally.
sodium intake
food, bev, use of salt shaker, salt tablets, intake can be excessive
sodium loss in sweat is generally low but
can be substantial for some people
sodium output in urine is typically high bc of
tight homeostatic control by the renal system
fecal losses of sodium are
small
sodium output
sweat, urine, feces
potassium intake
food, bev, occasionally the use of salt substitute
potassium intake tends to be low due to
lack of fruits, veg, and minimally processed foods
potassium output
- small losses in sweat or feces
- losses in urine tightly controlled by the renal system
- atypical losses such as vomiting and potassium depleting diuretic drugs can be dangerous
calcium intake
food (natural and fortified), bev, supplements
many people consume less ____ than is recommended
calcium
calcium output
- small losses in sweat
- larger losses in feces and urine
- blood calcium tightly regulated by several hormones which affect absorption, retention, and excretion
magnesium intake
food, bev, supplements
magnesium output
small losses in sweat and feces
most magnesium is lost via
urine; some diuretics increase urinary excretion
chloride intake
found as sodium chloride in food, bev, salt
chloride output
same as sodium
Distribution of water throughout the body is regulated by
both the volume of water and the osmolarity of the extracellular fluid
osmolarity is influenced by
the concentration of solutes, particularly certain electrolytes.
factors in exercise, sweat, and water loss
- exercise intensity
- environmental conditions
- clothing
- training status
Body temperature rises with exercise, but replacing fluid to slow or prevent dehydration prevents
the excessive rise in body temperature that occurs when no fluid is consumed.
sweat loss in non-exercise, temperate conditions
100 ml daily
sweat loss if exercising in high temp w protective clothing
1-2 L/hr
sweat loss in prolonged exercise in the heat
> 2.5 L/hr
sweat loss in cold environments
exhalation
hypovolemia
loss of blood volume
hypovolemia affects
blood flow and thus o2 delivery
hyperthermia can lead to
coma or death
hyperthermia
high body temp
basketball, 1500 m run, 5000 m run, 10,000 m run, soccer degree of dehydration
2%
wrestling degree of dehydration
> 4%
urine samples should be taken when
first thing in the morning
how should athletes assess their hydration status
- are they thirsty
- is their urine dark yellow
- has their body weight noticeably decreased since the previous morning
one: maybe
two: likely
three: very likely
hydration goals prior to training
Being fully hydrated prior to exercise
If not fully hydrated, rehydrating to the greatest extent possible
Avoiding gastrointestinal upset
Consuming carbohydrate, if appropriate
hydration goals during training
Replacing lost body water to the extent possible
Slowing dehydration to the extent possible
Avoiding the overconsumption of water and other hypotonic fluids
Replacing sodium if losses are large or rapid
Consuming carbohydrate if appropriate
Avoiding gastrointestinal upset
Customized to consider sweat rate, sweat composition, duration, clothing, and environmental conditions
hydration goals after training and performance
Restoring lost body water to achieve euhydration
Replacing sodium and other electrolytes lost
Consuming adequate carbohydrate to fully restore muscle glycogen
Consuming adequate protein to build and repair skeletal muscle
Avoiding gastrointestinal upset
Approximately 1.25–1.5 L (~50 oz, or ~6 cups) of fluid/kg of body weight lost, as soon after exercise as is practical
t or f: most body water is found in the ECF
false
t or f: in ECF, the major cation is potassium, and the major anions are chloride and bicarbonate
false
t or f: aerobic metabolism is a source of water for the body
true
t or f: hyperhydration is ideal for athletes bc this state ensures the athlete will stay hydrated throughout the activity
false
t or f: inc water vapor in the air reduces the ability of sweat secreted onto the skin to cool the body through evaporation
true
t or f: Body temperature rises with exercise, but replacing fluid to slow or prevent dehydration prevents the excessive rise in body temperature that occurs when no fluid is consumed.
true
t or f: Heavy sweating results in sodium loss that should be replaced during exercise if the duration of the activity exceeds 1 to 2 hours.
true
t or f: If an athlete consumes a typical amount of dietary sodium, there is little need for the fluid replacement beverage to contain sodium unless the exercise duration is more than 2 hours and there is a very high sweat rate.
true
t or f: To rehydrate after exercise, athletes should drink one pint (two cups) of fluid for every pound lost.
false
t or f: Preventing hyponatremia is a twofold process: prevention of fluid overload and underdrinking, and replacement of potassium.
false
strategy to prevent hyponatremia
prevention of fluid overload or overdrinking, and replacement of sodium.
fluid replacement to restore a one-pound water loss
~700 mL
why is hyperhydration dangerous
because excess water can dilute the concentration of solutes in the extracellular fluid, particularly sodium, resulting in hyponatremia.
Correct. In extracellular fluid, the major cation (positively charged ion) is ____ and the major anions (negatively charged ions) are ___ and ____
sodium; chloride; bicarbonate
In which compartment is the largest amount of body fluid stored?
intracellular fluid
Having a normal or optimal amount of water in the body, sufficient to support fluid balance and meet required physiological functions, would be termed:
euhydration
Which of the following electrolytes might be deficient in the diet of a person from an industrialized country (for example, the United States)?
potassium
Wearing uniforms and protective gear while exercising in the heat typically:
restricts the evaporation of sweat and results in body temperature rising.
A person exercising in a hot and humid environment might lose how much fluid through sweating?
1 to 2 L per hour
Water only is an appropriate pre-exercise beverage for:
exercise lasting less than 60 minutes.
Two factors that may be associated with hyponatremia include:
large losses of sodium in sweat and excessive water intake.
