Transcript File - twynham a level pe

Water and the body’s
electrolyte balance
http://www.youtube.com/watch?v=WzB-sPj9uOQ
Role of Water….
• 50-60% of adults body mass is water
• Regulates body temperature
• Carries nutrients and oxygen to all cells in body
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via blood plasma
Helps convert food into energy and absorbs
nutrients
Needed for expiration
Removes waste
Protects and cushions vital organs
Most basic but vital part of our
diet.
• Learning Objectives;
1. Role that water plays in
2.
3.
maintenance of body functions
Effects of dehydration
When/how fluids should be taken
Electrolytes
• Vital for functioning of cells/ essential
minerals
• Nutrients and waste products are
exchange
• They control osmosis of water between
body compartments
• They help maintain the acid-base balance
required for normal cellular activities (pH
is maintained)
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Sodium
Potassium
Chlorine (negatively charged)
Main but others include magnesium, calcium
• Needed for electrical impulses of nerve
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transmission
Dissolved in water
Deficiency in one can alter performance.
How we lose Electrolytes
• The sweat that evaporates from the skin
contains a variety of electrolytes. The electrolyte
composition of sweat is variable but comprises
of the following components:
• A litre of sweat typically contains 0.02g Calcium,
0.05g Magnesium, 1.15g Sodium, 0.23g
Potassium and 1.48g Chloride. This composition
will vary from person to person.
Lose water through
• Expulsion of waste products!
• Exhaling
• Sweating
• This depends on humidity, temperature,
altitude and type of exercise
How do we lose it?
• ¼-1/3 litre lost a day
• Most water loss; cold temperatures,
altitude- dry air
• AND- high temperatures…sweating
• Hot and humid conditions do not let sweat
evaporate so body can not cool itself.
What happens if we don’t maintina the correct
water and electrolyte
balance?
• Blood thickens/increase in viscosity
• Increase in heart rate/heart has to work harder
• Reduction in blood flow to working muscles/less oxygen to the
muscles
• Blood flow to skin reduces/increase in body temperature/heat
stroke/unable to maintain correct body temperature
• Slows reaction time/decision making/slows nerve impulses
• Muscle fatigue
• Muscle cramps
• Irregular heart beat
• Disruption to removal of waste products/lactic acid build up
Electrolyte Balance
• Proportion or concentration of electrolytes
within the fluid of the body.
• Why should we drink water with
electrolytes in?
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• Water on its own causes bloating
• Intake electrolytes and carbs
• Carbs make it more palatable
• And add energy value
How much?
Prior to Event
• 400-600ml fluid 2-3 hours before
• 350ml just before
• Eat carbohydrate meal 2-4 hours prior
During the Event
• Ingest water and carbs as much as possible even if not thirsty
• How convenient is it to hydrate?
• Lower GI absorbed more quickly – slow release.
After the Event
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Rarely able to keep themselves hydrated
Tend to underestimate level of hydration
Limited opportunities to intake fluid
Intolerance to in taking too much fluid
Underestimate how much sweating
• Must consume high carb meal post event
Effects of dehydration on
performance
• 2% impaired performance
• 4% capacity of muscles to work is
reduced
• %% Heat exhaustion
• 7% hallucinations
• 10% Circulatory collapse and Heat
Stroke
Exam Question
What are the effects of dehydration on an
athlete and how does this affect
performance?
(4 marks)
What are the effects of dehydration on an athlete and how
does this affect performance?
(4 marks)
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Increase blood viscosity
Reduced blood pressure
Reduced cardiac output
Reduced sweating to prevent water loss
Increased core temperature
Enzymes become denatured and do not perform to
optimum
• Unable to meet demands of exercise
• Decreased performance
Outline the physiological changes that will occur if
the correct water and electrolyte
balance is not maintained. (7)