7. Human Nutrition

• Balanced diet


  Consists of all of the food groups in the correct proportions
• Necessary food groups

  • Carbohydrates
  • Proteins
  • Lipids
  • Vitamins
  • Minerals
  • Dietary Fibre
  • Water
• Scurvy


  Severe vitamin C deficiency
• Scurvy


  1. Caused by lack of vitamin C in diet for over 3 months

  2. Symptoms include anemia, exhaustion, spontaneous bleeding, pain in limbs, swelling, gum ulcerations, tooth loss
• Scurvy was commonly seen in sailors between the 15th to 18th centuries
• Long sea voyages made it very hard to access a ready supply of fresh produce
• Treatment for scurvy

  Oral or intravenous vitamin C supplements
• Rickets


  Condition in children characterised by poor bone development
• Rickets


  1. Symptoms include bone pain, lack of bone growth, soft, weak bones (sometimes causing deformities)

  2. Caused by severe lack of vitamin D

  3. Vitamin D is required for the absorption of calcium into the body

  4. Calcium is a key component of bones and teeth

  5. Vitamin D mostly comes from exposure to sunlight but it can also be found in some foods (fish, eggs and butter)
• Treatment for rickets

  • Increase consumption of foods containing calcium and vitamin D
  • Alternatively vitamin D supplements can be prescribed
• Food Groups Table

  
• Vitamin and Mineral Requirements Table

  
• Varying Dietary Needs of Individuals Table

  
• Scurvy


  Severe vitamin C deficiency
• Scurvy


  • Caused by lack of vitamin C in diet for over 3 months
  • Symptoms include anemia, exhaustion, spontaneous bleeding, pain in limbs, swelling, gum ulcerations, tooth loss
  • Commonly seen in sailors between 15th to 18th centuries
  • Long sea voyages made it hard to access fresh produce
  • Can be treated with oral or intravenous vitamin C supplements
• Rickets


  Condition in children characterised by poor bone development
• Rickets


  • Symptoms include bone pain, lack of bone growth, soft weak bones (sometimes causing deformities)
  • Caused by severe lack of vitamin D
  • Vitamin D required for absorption of calcium into body
  • Calcium is key component of bones and teeth
  • Vitamin D mostly from sunlight exposure, also found in some foods (fish, eggs, butter)
  • Treated by increasing consumption of foods containing calcium and vitamin D, or vitamin D supplements
• Stages of food breakdown

  • Ingestion
  • Mechanical digestion
  • Chemical digestion
  • Absorption
  • Assimilation
  • Egestion
• Ingestion


  The taking of substances, e.g. food and drink, into the body through the mouth
• Mechanical digestion


  The breakdown of food into smaller pieces without chemical change to the food molecules
• Chemical digestion


  The breakdown of large, insoluble molecules into small, soluble molecules
• Absorption


  The movement of small food molecules and ions through the wall of the intestine into the blood
• Assimilation


  The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
• Egestion


  The passing out of food that has not been digested or absorbed, as feces, through the anus
• The human digestive system

  
• Functions of the Digestive Organs Table

  
• Physical Digestion

  • Physical digestion (sometimes referred to as mechanical digestion) is the breakdown of food into smaller pieces without chemical change to the food molecules
  • The processes that take place during physical digestion help to increase the surface area of food for the action of enzymes during chemical digestion
  • It is mainly carried out by the chewing action of the teeth, the churning action of the stomach and the emulsification of fats by bile in the duodenum
• Types of Human Teeth

  • Incisors
  • Canines
  • Premolars
  • Molars
• Mechanical digestion


  The breakdown of food into smaller pieces without chemical change to the food molecules
• Mechanical digestion

  1. Chewing action of the teeth

  2. Churning action of the stomach

  3. Emulsification of fats by bile in the duodenum
• Teeth


  • Held firmly in the bone of the jaw
  • Used for chewing to increase the surface area of the food so that it can be exposed to saliva and other digestive juices and broken down more quickly
• Incisors

  Chisel-shaped for biting and cutting
• Canines

  Pointed for tearing, holding and biting
• Premolars and molars


  Larger, flat surfaces with ridges at the edges for chewing and grinding up food
• Types of teeth

  
• Structure of a typical tooth

  
• The Stomach

  • The stomach is one of a number of organs that make up the digestive system
  • The role of the digestive system is to break down large insoluble molecules into smaller, soluble food molecules to provide the body with nutrients
  • The stomach lining contains muscles which contract to physically squeeze and mix the food with the strong digestive juices that are present
  • Also known as "stomach churning"
  • Food is digested within the stomach for several hours
• Three types of tissue found in the stomach are muscular, epithelial and glandular. These tissues work together to allow the stomach to carry out its role.

  
• Emulsification of Fats & Oils: Extended

  • Cells in the liver produce bile which is then stored in the gallbladder

  Bile has two main roles:

  • It is alkaline to neutralise the hydrochloric acid which comes from the stomach
  • The enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach
  • It breaks down large drops of fat into smaller ones. This is known as emulsification. The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster
• Bile production and secretion