ch5 food and humans

• Food substances essential to health

  • Carbohydrates
  • Protein
  • Lipids
• Primary food substances


  Keep us alive
• Water, carbohydrates, lipids, protein

  Provide energy
• Protective food substances


  Need small amount to keep us healthy
• Protective food substances


  • Dietary fibre
  • Minerals
  • Vitamins
• Carbohydrates


  Carbon, hydrogen in 2:1 ratio, oxygen
• Carbohydrate groups


  • Monosaccharides (simple sugars, small size pass through cell membrane)
  • Disaccharides
  • Polysaccharides
• Monosaccharides


  Glucose, fructose, galactose
• Disaccharides


  Maltose, sucrose, lactose
• Polysaccharides


  Glycogen, starch, cellulose
• Condensation


  How monosaccharides and disaccharides join together
• Hydrolysis


  How disaccharides and polysaccharides break down
• Uses of carbohydrates


  Main source of energy, energy reserve
• Carbohydrates


  • Sweet, soluble in water
• Protein


  Carbon, oxygen, sulphur, hydrogen, nitrogen are the basic elements
• Amino acid


  The basic unit of protein
• Protein structure


  1. Amino acid

  2. Dipeptide

  3. Polypeptide
• Essential amino acids


  Cannot be produced by the body, must be obtained from food
• Non-essential amino acids


  Can be produced by the body
• Protein


  • Unique sequence performs different functions, unique shapes like receptors and antibodies
• Functions of protein


  Repair and growth of body tissue, energy source (last)
• Protein deficiency


  Kwashiorkor - grow poorly, weak muscles, swollen abdomen
• Lipids


  Carbon, hydrogen ratio 2:1, oxygen, insoluble in water, soluble in organic solvents
• Triglycerides


  One glycerol + 3 fatty acids, formed by condensation, broken down by hydrolysis
• Fats


  Solid at room temperature, come from animals
• Oils


  Liquid at room temperature, come from plants
• Functions of lipids


  • Energy reserve, shock absorber, heat insulator, absorption and transport of lipid-soluble vitamins, production of hormones, component of cell membrane
• Minerals


  Inorganic food substances needed in small amounts, no energy value, regulate metabolic reactions, building body tissue
• Calcium


  Component of bones and teeth, involved in blood clotting, muscle contraction, and sending messages in nervous systems
• Calcium deficiency


  Rickets in children, osteoporosis
• Sources of calcium


  Dairy products, canned sardines, milk, kale, broccoli, spinach, some pre-packaged food/drinks
• Iron


  Component of haemoglobin, molecule of red blood cells
• Iron deficiency


  Anaemia - faint easily, not enough haemoglobin in red blood cells to carry oxygen to brain
• Sources of iron


  Beef, liver, beans, cabbage, spinach, raisins
• Vitamins


  Organic food substances needed in small amounts, no energy value, regulate metabolic reactions
• Types of vitamins


  • Lipid soluble (A, D, E, K)
  • Water soluble (B, C)
• Lipid soluble vitamins


  Absorbed with lipids, stored in large amounts, can be harmful if taken in too large amounts
• Water soluble vitamins


  Can't be stored in large amounts, excess excreted through urine, important to take regularly
• Vitamin A


  Formation of pigment in retina, keep cornea, skin, lining of alimentary canal and breathing system healthy
• Vitamin A deficiency


  Poor vision in dim light/night blindness, drying up of cornea and skin, easy infection of lining of lungs and cornea