Human Nutrition

  1. A balanced diet - consists of all the food groups in the correct proportions

  2. Carbohydrates - provide energy for respiration in cells. Eg. pasta, rice, potatoes

  3. Fats - used as long term stores of energy, layer of fat underneath skin acts as insulation. Eg. cheese, fatty meats, butter

  4. Protein - All cells contain protein, so it is a vital substance for growth and repair of tissues. Eg. fish, meat, eggs.

  5. Vitamin C - maintain healthy skin and gums. deficiency causes scurvy where wounds do not heal and there is excessive bleeding like in gums. Eg. citrus fruits

  6. Vitamin D - helps the body absorb calcium, which is needed for strong bones and teeth. Deficiency causes rickets causes weak or soft bones and deformities. Eg. dairy products, fish oil, eggs

  7. Mineral ions: Calcium - needed for strong bones and teeth, plays a role in blood clotting. Eg. milk, cheese, eggs

  8. Mineral ions: Iron - needed to make hemoglobin present in red blood cells, helps carry oxygen around the body. Eg. read meat, green vegetables like spinach

  9. Fibre (roughage) - helps food to move through stomach and intestines. Eg. vegetables, fruits, whole grains

  10. Water - needed for chemical reaction to take place in cells 

  11. Digestive system - role is to break down large insoluble molecules into smaller soluble food molecules to provide the body with nutrients eg. the alimentary canal: mouth, esophagus, stomach, small intestine (duodenum and ileum) and large intestine (colon, rectum, anus) 

  12.  Salivary glands, pancreas, liver, gall bladder

  13. Ingestion - the taking of substances eg. food and drink into the body 

  14. Digestion - the breakdown of food

  15. Absorption - the movement of nutrients from the intestines to the blood, i.e. nutrients move from digestive system to circulatory system e.g. small intestine where nutrients are absorbed, most water is absorbed in small intestine but also in colon 

  16. Assimilation - the uptake and use of nutrients i.e. nutrients move from circulatory system to cells 

  17. Egestion - removal of undigested food from the body as feces. 

  18. Physical Digestion - the breakdown of food into smaller pieces without chemical change to food molecules, increases the surface area of food for the action of enzymes in chemical digestion, mainly carried out by the teeth, stomach, bile in duodenum

  19. Teeth - canines, incisors, premolars, molars

  20. Incisors - for biting and cutting

  21. Canines - for tearing holding and biting

  22. Premolars - for chewing and grinding

  23. Molars - for chewing and grinding

  24. Structure of tooth - enamel, cement, dentine, pulp cavity, nerves, blood vessels, bone, gums

  25. Stomach - physical digestion occurs as the stomach walls to squeeze the food to liquify it i.e. the lining of the stomach contains muscles which contract to physically squeeze and mix the food with the strong digestive juices that are present in the stomach.

  26. Bile - alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action. It is made by the liver, stored in the gall bladder, secreted from bile duct into the duodenum for 2 reason. 1. Alkaline so neutralises the hydrochloric acid which comes from the stomach. 2. Breaks down large drops of fat into smaller ones, aka emulsification. 

  27. Chemical digestion - the breakdown of large insoluble molecules into small soluble molecules, the role of chemical digestion is to produce small soluble molecules that can be absorbed 

  28. Digestive enzymes - 1. Amylase: starch to maltose e.g. produced in salivary glands acts in mouth, duodenum
    2. Maltase: maltose to glucose e.g. produced in pancreas and acts in membranes of the epithelium lining the small intestine
    3. Protease (pepsin): protein to amino acids e.g. produced and acts in stomach where acidic conditions
    4.  Protease (trypsin): protein to amino acids e.g. produced in pancreas, acts in duodenum where alkaline conditions
    5. Lipase: breaks down fats and oils into fatty acids and glycerol e.g. produced in pancreas, acts in duodenum

  29. Functions in HCL in gastric juices - killing harmful microorganisms in food, provides an acidic pH for optimum enzyme e.g. pepsin activity

  30. Villi - The ileum is adapted for absorption as it has a highly folded surface with millions of villi and microvilli, which are tiny fingerlike projections. These greatly increase the internal surface area of the ileum, allowing absorption to take place faster and efficiently

  31. Structure of villus - thin surface layer, microvilli, capillaries: absorb glucose and amino acids and carry it away from the small intestine in the blood, blood vessels, lacteals: absorb fatty acids and glycerol and transport them away from the small intestine in the lymph