Animal (Human) Nutrition

• We need food to :

  • to supply us with 'fuel' for energy
  • to provide materials for growth and repair of tissues
  • to help fight disease and keep our bodies healthy
• • Carbohydrates
  • Fibre
  • Vitamins
  • Lipids
  • Proteins
  • Minerals
  • Water
• Carbohydrates : Glucose, Lactose, Fructose, Sucrose (=simple sugars)

  Starch, Glycogen (=polysaccharides)
• Carbohydrates are used by the body for respiration to release energy
• Too much energy = stored as fat
• Lipids (Fats and Oils) : used for :

  • making cell membranes
  • insulation
  • protection of organs
  • energy store
• Proteins : needed for growth and repair of tissues, replacement of cells
• Vitamins :

  Vitamin A : Maintains retina in eye

  Vitamin C : Stick cells together, making connective tissue. Lack of: Scurvy, fingernails bleed, bleeding gums

  Vitamin D : helps bones absorb calcium
• Minerals :

  • Calcium : making teeth and bones, lack of calcium : rickets
  • Iron : used to make haemoglobin in red blood cells, lack of iron : anaemia
• Water :

  • stay hydrated
  • maintains osmosis correctly in cells
  • it provides a solvent for enzymes and food molecules
  • it is an important component of blood plasma
• Dietary fibre :

  • mostly made from cellulose from the plant cell walls we eat
  • cannot be digested
• Digestion is the chemical and mechanical breakdown of food.
• Define Digestion

  Digestion is the chemical and mechanical breakdown of food.
• Digestion Converts

  large, insoluble molecules into small soluble molecules, which can be absorbed into the blood.
• Mouth, Oesophagus, Stomach, Duodenum, Ileum, (small intestine), Colon, Rectum, (large intestine), anus
• Accessory Organs:

  • Salivary glands
  • Liver
  • Gallbladder
  • Pancreas
  • Appendix
• Mouth in Digestion

  • the enzyme amylase in the saliva breaks down starch into maltose
  • teeth break the food down into larger surface area for the enzymes to work
• • the enzyme amylase in the saliva breaks down starch into maltose
• Stomach in Digestion :

  • stomach wall churns up the food
  • stomach lining secretes hydrochloric acid
  • hydrochloric acid kills bacteria
  • pepsin (a protease enzyme) breaks down protein into amino acids
• Duodenum in Digestion :

  • pancreatic juice contains : trypsin, amylase, lipase. this enters the duodenum
  • amylase : breaks down starch into maltose
  • trypsin : breaks down proteins into amino acids
  • lipase : breaks down lipids into fatty acids and glycerol (with the help of bile)
  • bile is made in the liver and stored in the gallbladder
  • bile emulsifies large lipids
• • bile is made in the liver and stored in the gallbladder
• The Ileum in Digestion

  • food molecules absorbed into blood
  • large surface area due to villi and microvilli
  • each villus contains a network of blood vessels and a lacteal
  • lacteals absorb the products of fat digestion into the lymphatic system
  • the food molecules get transported into the blood to the tissues where they get assimilated into cells
• Large Intestine in Digestion

  • Colon absorbs water
  • Faeces is stored in the rectum, expelled through the anus = egestion
• • colon absorbs water
• Amylase is made in

  • salivary glands
  • pancreas
  • small intestine
• protease breaks down proteins into amino acids
• proteases are made in :

  • stomach (where it is known as pepsin)
  • pancreas
  • small intestine
• fats are broken down by lipase into glycerol and fatty acids
• Lipase is found in

  • pancreas
  • small intestine