water

• Facts about water linked to food and the body

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
• What I Will Learn - Water

  • Describe the composition and properties of water
  • Assess the sources of water in the diet
  • Examine the functions of water in the body
  • Recognise the effects of dehydration
• Water is essential for all life
• Our bodies are 70% water
• Each day we lose approximately 2–2.5 litres through perspiration (the production of sweat to cool down the body) and urination
• 2 litres or eight glasses of water per day is recommended
• Composition of water


  Each water molecule contains the elements hydrogen (H) and oxygen (O) in a 2:1 ratio
• Properties of water


  • Water boils at 100 'C and freezes at 0 oC
  • Water can be solid (ice), liquid (water) or gas (vapour)
  • Pure water is tasteless, colourless and odourless
  • Some substances dissolve easily in water, e.g. salt (making brine) and sugar
• Sources of water


  • Food: Most foods contain water, apart from fats and dried foods, e.g. flour and sugar
  • Drinks: water, milk, juices, tea and coffee
• Functions of water


  • Water is an essential part of all body tissues and fluids, e.g. blood
  • It transports nutrients and oxygen to all body cells
  • It helps to remove waste products from the body through urine
  • Water regulates body temperature through perspiration (sweat)
• Dehydration


  Occurs when the body loses more water than it takes in
• Dehydration is common after a period of vomiting or diarrhoea or if too much alcohol is consumed
• Symptoms of dehydration


  • Dry mouth
  • Bad breath
  • Headache
  • Low blood pressure
  • Dizziness
• Dehydration is particularly dangerous in babies and older people