Digestive System

• Digestive system - responsible for breaking down of food into nutrients that are necessary for the maintenance, growth, and

  energy needs of the body.
• 1. Oral Cavity – Lips, teeth, palate, tongue
  2. Alimentary Tract/GI Tract – Esophagus, Stomach, Small Intestine, Large Intestine, Anus
  3. Accessory Glands/Organ – Salivary glands, liver, and pancreas
• • Ingestion, or introduction of food and liquid into the oral cavity
  • Mastication, or chewing, which divides solid food into digestible pieces
  • Motility, muscular movements of materials through the tract
• MUCOSA (MUCOUS MEMBRANE)

  • consists of an epithelial lining; an underlying lamina propria of loose connective tissue rich in blood vessels, lymphatics, lymphocytes, smooth muscle cells, and often containing small glands.
  • a thin layer of smooth muscle called the muscularis mucosae separating mucosa from submucosa and allowing local movements of the mucosa.
• SUBMUCOSA

  • contains denser connective tissue with larger blood and lymph vessels and the submucosal (Meissner) plexus of autonomic nerves.
  • It may also contain glands and significant lymphoid tissue.
• THICK MUSCULARIS (MUSCULARIS EXTERNA)

  • composed of smooth muscle cells organized as two or more sublayers. (except in the esophagus), responsible for peristalsis [wave-like muscle contractions]
  • also arranged in inner circular and outer longitudinal layers
  • Between the layers is the parasympathetic nerve plexus