2.1 Enzymes and Digestion

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  • Created by: Martyn
  • Created on: 25-11-14 15:09
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  • 2.1 Enzymes and Digestion
    • Major parts of the digestive system:
      • Oesophagus: Thick muscular wall - carries food from mouth to stomach - adapted for transportation rather than digestion or absorption.
      • Stomach: Muscular sac with inner layer producing enzymes - stores and digests food especially proteins - produces protease - has mucus lining- prevent being digested by own enzymes.
      • Small Intestine: Long muscular tube - digests food using enzymes produced in its walls and glands - lining has villi and micro villi to increase surface area - more molecules into bloodstream.
      • Large Intestine: Absorbs water - mostly from secretions of many digestive glands - food becomes drier and thicker forming faeces.
      • Rectum: Final section of intestines - faeces stored here before being excreted by anus during egestion.
      • Salivary Glands: Situated near mouth - passing secretions containing amylase to digest starch via duct into mouth
      • Pancreas: Gland below stomach - produce pancreatic juice containing protease, amylase and lipase.
    • Digestive System: Long muscular tube and glands - produce enzymes to break down food molecules into smaller ones for digestion.
    • Digestion takes place in two stages:
      • Physical Breakdown
        • Food broken down into small pieces by structure i.e. teeth - allows food to be ingested and increases surface area for chemical digestion.
        • Food churned by stomach muscles to physically break it up.
      • Chemical Digestion
        • Breaks down large, insoluble molecules into smaller, soluble ones - carried out by enzymes.
        • Digestive enzymes function by hydrolysis - the splitting up of molecules by adding water to the holding chemical bonds - hydrolases are the general term.
        • Enzymes are specific so more than one needed to break down a large molecule - one splits into sections then these sections are hydrolysed into smaller molecules.
        • Types of digestive enzymes: Carbohydrates - break down carbohydrates to mono-saccharaides. Lipases - break down lipids into glycerol and fatty acids. Proteases - break down proteins into amino acids.
        • Once molecules hydrolysed they are absorbed from small intestine into blood - carried around the body and built up again - incorporated and used by the body- process called assimilation.

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