The digestive system

The digestive system

1. The alimentary canal is used to describe the pathway of digestion, from the mouth to the rectum

2. convert complex nutrients into forms which can be absorbed and used by the body

3. Buccal cavity

   • 10-12 litres of saliva produced daily
     • mucus, water and bicarbonate salts to regulate pH of stomach
   • 3 salivary glands
   • Oesophagous
     • cardiac sphincter
       • Stomach
         • 8-15 litres, acidic, digesta remains here for 3 hours, optimal function when 2/3 full
         • Digesta+hydrochloric acid+enzymes=chyme
         • Pyloric sphincter
           • Small intestine
             • 20 meters long, most of the digestion occurs here
             • Duodenum - Enzymes from liver and pancreas break down digesta by chemical digestion Bile is also released
             • Jejunum - absorption
             • Ileum - Regulates entry of digesta into the large intestine via the ileocaecal junction - common site for tapeworm infestation, can lead to colic
             • Large intestine
               • Microbial fermentation
               • Caecum
                 • Blind ended microbial fermentation sac
                 • Large colon
                   • 3 main bends: Sternal flexure - Diaphragmatic flexure - Pelvic flexure
                   • Some microbial fermentation
                   • Small colon
                     • Electrolyte and water absorption
                     • Rectum
                       • stores undigested material
                       • Anus
                         • Ejestion
       • Prevents horse regurgitating food
     • 1.5m muscular tube
     • Peristalsis

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