Water + Electolytes

Water

• essential for life in all organisms

• efficient solvent meaning it can transport nutrients to cells, remove waste products and transport metabolites in cells

• allows redistribution of heat around body and reduces temp through evaporation in sweat

• medium essential for biochemical reaction of metabolism in and out of cells

water in body

• 50-70% of total body mass is water

• depends on fat percentage

intracellular fluid

• fluid inside cells

• approx 2/3 of body fluid

extracellular fluid

• fluid outside of cells

• approx 1/3 of body fluid

interstitial fluid

• 80% of ECF which is found in spaces between cells of tissues

• plasma is the final 20%

osmotic concentration

measure of solute concentration in a solution, also known as osmolarity

dehydration

• dynamic process of losing water

Euhydration

• normal body water content

• absense of hyper or hypohydration

hyperhydration

state of excess body water content

hypohydration

state of insufficient/ suboptimal body water concentration

diuretic

substance that increases the rate of which urine is produced

water balance

• day to day fluctuations are roughly 2.5 litres in healthy, non-exercising people

• Water loss occurs through

  • evaporation from skin (sweat)

  • evaporation from respitory tract (breathing)

  • excretion from kidney (urine)

  • excretion from large intestine (feaces)

osmoregulation

a negative feedback loop that regulates water balance in body

osmoregulation step-by-step

1, hypothalamus detects changes in blood water levels

2, hypothalamus signals pituitary gland to release anti-diuretic hormone (ADH)

3, ADH travels to kidneys and signals them to reabsorb more water from urine

4, Reduces concentration of solutes in the blood and restores water balance

temporary hypohydration/dehydration

1, hypothalamus detects drop in water level

2, activation of sensation of thirst and pituitary gland releases ADH

3, Kidneys reabsorb more water from urine

4, Body conserves fluids and restores water balance

Temporary hyperhydration

1, pituitary gland supresses ADH production

2, kidneys excrete more water in urine

3, body restores water balance by removing excess water

kidneys

• control retention and loss of water

• diagram - movement of fluid

3 ways to monitor hydration status

• measure body mass

• urine color

• urine testing with osmometer

hot conditions impact on hydration

• water balance can be disrupted due to exercise or hot environments

• metabolic heat is lost through sweat evaporation

• sweat loss is greater in hot climates so more water is needed to avoid dehydration

• dehydration increases health risk like heat stroke

• athletes should avoid losing more then 2% body mass by fluid loss

Regulation of electrolytes during exercise

1, at start of exercise, water moves from plasma to interstitial and intracellular spaces

2, water movement is determined by amount of active muscles and exercise intensity

3, metabolic by products increase asmatic pressure

4, muscle activity raises blood pressure, forcing water out of blood and. reducing plasma volume

5, hypothalamus, pituitary gland, and kidneys regulate water levels and electrolyte balance

hyponatremia

• condition where concentration of sodium in body fluid is too low

• occurs during endurance sports

• symptoms include: bloating, nausea, vomiting, and heaaches

• can cause brain swelling, seizuers, coma, and sometimes dealth

hypernatrimea

• condition where concentration of sodium in body fluid is too high

• result of dehydration or excess sodium

• symptoms include: bloating, nausea, vomiting, and headaches

• can cause brain swelling, seizures, coma, and sometimes dealth

• occurs during or up to 24 hours after physical activity

cardiovascular drift

phenomenon characterised by rise in heart rate and fall in stroke volume over time, during prolonged aerobic exercise at a steady intensity