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what are the 9 fxns of water in the body:
- forms the fluid portion of blood
- maintains blood volume
- participates in metabolic rxns
- serves as a solvent for proteins, glucose, vitamins, and minerals
- forms fluid portion of sweat (cooling)
- carries heat from inside the body to the skin (cooling)
- lubricates joints
- forms spinal & eye fluid
- forms amniotic fluid in the womb
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what are the three ways water can be "taken into" or generated in the body:
- liquids: water, milk, juice, ect.
- foods: shrimp, bananas, corn, potatoes
- metabolic water: water generated by metabolic rxns
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the amount of water needed to be ingested varies with what 3 things:
- phyiscal activity performed
- environmental temperature
- environmental humidity
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how much water is lost from the body per day?
how much water should be ingested to maitain normal hydration:
- h2o lost from the body per day: 2.5 L
- ingested to maintain hydration: total water intake need to match total water loss
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a normal hydration level is called:
euhydration
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net water loss, leading to dehydration is called:
hypohydration
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how much water is typically lost throughout the day in the following mediums:
urine:
sweat:
feces:
insensible:
total:
- urine: 500-1400 ml
- sweat: 400-900 mL (with exercise)
- feces: 150 mL
- insensieble perspriation: 350 mL
- total per day: 1400-2800 mL per day
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mineral salts that dissolve in water and form ions are called:
electrolytes
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charged molecules are called: ions
positively charged molecules are called:
negatively charged molecules are called:
- charged molecules are called: ions
- postitively charged molecules are called: cations
- negatively charged molecues are called: anions
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what are the 3 important fxns of electrolytes:
- allow electrical charges to occur
- essential to excitable tissues ( neurons & muscle fibers)
- create force (osmotic pressure) to hold water & move it through membranes as needed
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the force created to draw water thru a memebrane is called:
how do cells indirectly controll the movement of water:
what mechanism allows this to indirect movement to occur:
the force created to draw water thru a memebrane is called: osmotic pressure
- -cells indirectly control the movement of water by directly controlling the movements of electrolytes, since water follows electrolytes
- -mechanism: sodium-potassium pump
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if a membrane permable to water seperates two volumes how does water move if.....
there are equal concentrations of electrolytes:
if there are more electrolytes on one side of the membrane:
- equal concentrations of electrolytes: no tendency for water to move in either direction
- more electrolytes on one side of the membrane: tendency for water to move toward the side of the membrane with greater concentrations of electrolytes
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how is electrolyte balance controlled within the body:
- kidneys
- if Na+ content is low, kidneys conserve Na+ by reabsorbing from urine
- controlled by hormonal mechanisms: aldosterone; conservation of sodium
- gastrointestinal tract
- absorbs minerals (mineral salts dissolve in water, forming electrolytes) ((then into bloodstream))
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a fluid that has a lower osmotic pressure than that of blood is called:
give an example:
- a fluid that has a lower osmotic pressure than that of blood is called: hypotonic
- example: sweat
- seat has fewer electrolytes than does blood
- in intense exercise/heat 3-4 L hr-1 of sweat can be lost
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list 4 adaptions of sweat due to the acclimatization to heat:
- higher sweat rate
- ealier onset of sweating
- increased plasma volume
- reduced electrolyte content of sweat
- -although, fewer electrolytes are lost per volume of sweat to maintain balance
- -GI and Kidneys are capable of reabsorbing electrolytes, discouraging imbalances
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urine electrolyte content of urine will vary to help ensure electrolyte balance:
how does urine electrolyte content vary during exercise compared to at rest:
what 2 factors vary sodium excretion:
during exercise: as intensity increases, sodium excretion decreases
- 2 factors of sodium excretion
- less sodium excreted per liter of urine
- urine output increase from rest to light exercise then decreases during moderate exercise
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a conscious desire to drink and is involved in maintaining hydration and water balance is called:
how is this mechanism controlled in the brain:
- a conscious desire to drink and is involved in maintaining hydration and water balance is called: thrist
- brain control: hypothalamus that sense plasma osmolality
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how is the thrist mechanism typically stimulated:
as fluid is ingested, what happens to the concentration of dissolved fluids:
- how is the thrist mechanism typically stimulated: when body water is lost, the concentration of dissolved substances within the blood adn bodily fluids increase
- as fluid is ingested, what happens to the concentration of dissolved fluids: concentration of dissolved fluids returns toward normal, drive to drink diminshes
- humans are slow hydrators
- thrist mechanism does not result in restoration of water balance quickly
- becuase of this... athletes should consume fluids before starting the exercise session
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during exercise, dehydration commonly results due to:
dehydration results due to: sweating
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the mechanism of dissipating the heat generated by the increased burning of energy is called:
the effectiveness of this mechanism depends on:
- sweating
- effectivness depends on: relative humidity in the environment (more effective in dryer)
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water lost thru sweating comes from 4 areas in addition to sweat glands:
- intracellular and extracelluar compartments (plasma)
- muscle tissue & skin
- internal organs
- bones
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how is the cardiovascular system compromised by dehydration for aerobic capabilities:
- decreased plasam volume
- decreased stroke volume
- increased heart rate
- these 3 attempt to maintain cardiac output
- (Q=HR x SV)
decreased cardiac output
increased systemic resistance (vasoconstriction)
decreased blood pressure
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how is thermoregulation compromised by dehydration for aerobic capabilities:
- increased core temperature: hyperthermia
- decrease in skin blood flow
- decreased sweat rate
diminishing the ability to dissapate heat
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how are metabolic fnxs compromised as a result of dehydration:
- increased glycogen as a metabolic substrate
- increased blood lactate levels
these factors decrease preformance due to fatigue from increase glycogen and increased acidity
- decreased VO2peak
- deacreased peak lactate value
- decreased lactate threshold
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are the effects of dehydration more likely to affect anaerobic or aerobic performance:
why:
dehydraption is more likely to affect: aerobic performance
- why
- Decrease in plasma volume & cardiac output don’t affect anaerobic activity
- Anaerobic capability decrements more likely with heat exposure
- Strength decrements more likely in upper body
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the primary goals of fluid ingestion during a marathon event is:
what are 2 factors that affect the amount of fluid intake needed for a marathon:
- 2 goals
- prevent dehydration
- electrolyte replacement
- 2 factors that affect the amount
- the greater the body mass, the greater then fluid intake needed
- the greater the heat & humidity, the greater the fluid intake needed
- endurance capabilities are decreased by dehydration of as little as 2% of total body mass
- programmed and ad libitum drinking can be used to maintain hydration during a marathon
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wrestlers typically lost 5-6% of total body mass to make a weight class, how is this usually accomplished:
how does dehydration of 5-6% impact the performance:
- loss of total body mass accomplished by: caloric and fluid restriction
- dehydration of 5-6% results in: decrements in strength and anaerobic performance
- decreases were a result of combined effect of weight loss, dehydration, & competing in tournament
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how can dehydration affect the performance in team ball sports:
- decreased aerobic performance in later stages of contest
- decreased anaerobic capabilities (sprinting)
- decreased power/strength (jumping)
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how can dehydration affect the performance in a baskeball team:
how can dehydration affect the performance ina soccer team:
- decreased shooting percentage (8%)
- decreased sprint ability percentage (2%)
- decreased lateral movement ability (5%)
soccer: decreased performance of yo-yo intermittent recovery test ( by 15%)
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list the factors that can predispose individual or groups to dehydration:
- envrionmental factors: high temperature or high humidity
- athletes who dehydrate to make a weight class
- protective equimpent: interfere w/ heat loss
- dark colored clothing: greater heat absorption, increased sweating
- illness: fever or diarrhea
- age: loss of extracelluar fluid, decreased plasma volume, decreased osmolarity
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list and describe the 2 methods of field hydration assesment methods:
- assesment of body mass
- euhydration: maintenacne within +- 1% of per-exercise value
- dehydration: losses > 1% of pre-exercise body mass
- assesment of urine color
- euhydration: light color
- dehydration: dark color
- may be skewed if taking supplements (darken urine) or drinking fluids after an exercise sessio
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water intoxication due to a low blood sodium concentration is called:
this condition results in an osmotic imbalance which can lead to:
- hyponatremia
- osmotic imbalance can lead to: fluid movement into the brain, causing swelling of the brain (disorientation, confusion, weakness, grand mal seizures, coma, death)
- can also be caused by excessive sodium lost in sweat
- more likely in women than in men
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the guidelines for fluid consumption
begin activity in a euhydrated state:
maintain hydration during activity:
rehydrate after activity:
- begin activity in a euhydrated state: 17-20oz 2 to 3 hours before event, 200-300 mL 10 to 20 mintues before event
- maintain hydration during activity: 200-300 mL every 10 to 20 minutes
- rehydrate after activity: within 2 hours, drink enought fluid to replace lost body weight, for rapid rehydration drink 25-50% more fluid than sweat lost
- fluids should be palatable, cool, and contain electrolytes
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describe how to develop a hydration plan
- indiviudalized hydration
- plan will be modified with changing seasons and conditions
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