AS Biology - Unit 1 - Digestive System

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  • Unit 1 - Digestive System
    • Salivary Glands: Enzyme - amylase, Class - carbohydrase, Hydrolyses - starch, Into - maltose
    • Stomach: Enzyme - pepsin, Class - protease, Hydrolyses - protein, Into - peptides
    • Pancrease
      • Enzyme - amylase, Class - carbohydrase, Hydrolyses - starch,into - maltose
      • Enzyme - trypsin, Class - protease, Hydrolyses - protein, Into - peptides
      • Enzyme - chymotrypsin, Class - protease, Hydrolyses - protein, Into - peptides
      • Enzyme - corboxypeptidase, Class - protease, Hydrolyses - peptides, Into  amino acids
      • Enzyme - lipase, Class - lipase, Hydrolyses - lipids, Into - fatty acids + glycerol
    • Ileum
      • Enzyme - maltase, Class - carbohydrase, Hydrolyses maltose, Into - glucose
      • Enzyme - sucrase, Class - carbohydrase, Hydrolyses - sucrose, Into - glucose + fructose
      • Enzyme - lactase, Class - carbohydrase, Hydrolyses - lactose, Into - glucose + galactose
      • Enzyme - peptidase, Class - protease, Hydrolyses peptides, Into - amino acids
    • 1) Oesophagus: tube takes food down into the stomach using a wave of contractions called peristalsis. Mucus is secreted from the tissues in the walls to lubricate the foods passage downwards.
      • 2) Stomach: It has many folds, allowing it to expand - it can hold up tp 4 litres of food and drink. Exit and entrance of stomach are controlled by sphincter muscles. Stomach walls produce gastric juice, helps to break food down. This only works in acidic conditions. Peristalsis of the stomach turns food into acidic fluid called chyme
        • 3) Small Intestine: Duodenum and Ileum. Bile and pancreatic juice neutralise the acidity of the chyme, and also break it down further into smaller molecules. small soluble molecules are absorbed through structures called villi in the gut wall. Molecules are absorbed by diffusion, facilitated diffusion and active transport.
          • 4) Large Intestines: Absorbs water,salts and minerals. Folded wall for larger surface area. Bacteria that decompose some of the undigested nutrients are found in the large intestine.
            • 5) Rectum: Faeces are stored and then pass through sphincter muscles in the anus during defecation

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