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7. Human nutrition

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  1. 7.1 Diet

    1. • Describe what is meant by a balanced diet

    2. • State the principal dietary sources and describe the importance of: (a) carbohydrates (b) fats and oils (c) proteins (d) vitamins, limited to C and D (e) mineral ions, limited to calcium and iron (f) fibre (roughage) (g) water

    3. • State the causes of scurvy and rickets

  2. 7.2 Digestive system

    1. 7.2.1Main organs of the digestive system

      • Identify in diagrams and images the main organs of the digestive system, limited to: (a) alimentary canal: mouth, oesophagus, stomach, small intestine (duodenum and ileum) and large intestine (colon, rectum, anus) (b) associated organs: salivary glands, pancreas, liver and gall bladder

    2. 7.2.2Functions of the organs

      • Describe the functions of the organs of the digestive system listed in 7.2.1, in relation to: (a) ingestion – the taking of substances, e.g. food and drink, into the body (b) digestion – the breakdown of food (c) absorption – the movement of nutrients from the intestines into the blood (d) assimilation – uptake and use of nutrients by cells (e) egestion – the removal of undigested food from the body as faeces

  3. 7.3 Physical digestion

    1. • Describe physical digestion as the breakdown of food into smaller pieces without chemical change to the food molecules

    2. • State that physical digestion increases the surface area of food for the action of enzymes in chemical digestion

    3. • Identify in diagrams and images the types of human teeth: incisors, canines, premolars and molars

    4. • Describe the structure of human teeth, limited to: enamel, dentine, pulp, nerves, blood vessels and cement, and understand that teeth are embedded in bone and the gums

    5. • Describe the functions of the types of human teeth in physical digestion of food

    6. • Describe the function of the stomach in physical digestion

    7. • Outline the role of bile in emulsifying fats and oils to increase the surface area for chemical digestion

  4. 7.4 Chemical digestion

    1. • Describe chemical digestion as the breakdown of large insoluble molecules into small soluble molecules

    2. • State the role of chemical digestion in producing small soluble molecules that can be absorbed

    3. • Describe the functions of enzymes as follows: (a) amylase breaks down starch to simple reducing sugars (b) proteases break down protein to amino acids (c) lipase breaks down fats and oils to fatty acids and glycerol

    4. • State where, in the digestive system, amylase, protease and lipase are secreted and where they act

    5. • Describe the functions of hydrochloric acid in gastric juice, limited to killing harmful microorganisms in food and providing an acidic pH for optimum enzyme activity

    6. • Describe the digestion of starch in the digestive system: (a) amylase breaks down starch to maltose (b) maltase breaks down maltose to glucose on the membranes of the epithelium lining the small intestine

    7. • Describe the digestion of protein by proteases in the digestive system: (a) pepsin breaks down protein in the acidic conditions of the stomach (b) trypsin breaks down protein in the alkaline conditions of the small intestine

    8. • Explain that bile is an 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

  5. 7.5 Absorption

    1. • State that the small intestine is the region where nutrients are absorbed

    2. • State that most water is absorbed from the small intestine but that some is also absorbed from the colon

    3. • Explain the significance of villi and microvilli in increasing the internal surface area of the small intestine

    4. • Describe the structure of a villus

    5. • Describe the roles of capillaries and lacteals in villi