The Alimentary Canal

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The Alimentary Canal

• Part One

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Parts of the Digestive System

• Alimentary canal
• The tube through which food passes though the
  body
• Accessory organs
• Salivary glands, liver, gall bladder, pancreas

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Four Stages of Food Processing

• Ingestion
• Eating
• Digestion
• Mechanical digestion breaking food into smaller
  pieces
• Chemical digestion breaking food into simpler
  chemicals with digestive juices
• Absorption
• Movement of nutrients from alimentary canal to
  the bloodstream
• Elimination
• Passing undigested material out of the body

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Structure of the Alimentary Canal

• The wall of the tube has 4 layers
• Mucosa (mucous membrane)
• Surface epithelium surrounding the lumen
  (passageway) of the tube
• May contain glands or villi
• Secretion, absorption, protection
• Submucosa
• Contains connective tissue, glands, blood
  vessels, lymphatic vessels, nerves
• Nourishes tissues, carries away nutrients

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• Muscular layer
• Two layers of muscle
• Longitudinal fibers change length of the tube
  (churning mixing)
• Circular fibers change diameter of the tube
  (peristalsis)
• Serosa
• Visceral peritoneum
• Protection, lubrication

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The Mouth

• Teeth tongue chew food
• Salivary glands secrete saliva
• Serous cells secrete salivary amylase
• Begins breakdown of starches
• Mucous cells secrete mucus
• Lubrication
• 3 locations
• Parotid glands near ears
• Submandibular glands floor of mouth, near lower
  jaw
• Sublingual glands floor of mouth, near tongue

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Pharynx Esophagus

• Pharynx
• No digestion
• Swallowing
• Esophagus
• No digestion
• Peristalsis
• Mucous glands secrete mucus for lubrication