GIT micro anatomy

• How long is the gastrointestinal tract?

  9 m long
• What do accessory glands secrete into the alimentary tract?

  Substances used in digestion
• What are the four portions of the gastrointestinal tract?

  • Mucosa
  • Submucosa
  • Muscularis externa
  • Serosa / Adventitia
• What is the primary function of the gastrointestinal tract?

  Digestion and absorption of nutrients
• What are the divisions of the mucosa?

  • Epithelium
  • Lamina propria
  • Muscularis mucosae
• What is the role of the epithelium in the mucosa?

  Secretion, absorption, and protection
• How does the lamina propria contribute to the mucosa?

  Contains blood vessels and gut glands
• What is the composition of the muscularis mucosae?

  Two thin layers of smooth muscle
• What is found in the submucosa?

  • Collagenous and elastic connective tissue
  • Small blood vessels
  • Meissner’s nerve plexus
  • Glands in some regions
• What does the Meissner’s nerve plexus control?

  Motility, secretion rates, and blood flow
• What are the two layers of the muscularis externa?

  Inner circular and outer longitudinal
• What is the function of the muscularis externa?

  Performs peristaltic movements of the gut
• What is the serosa composed of?

  Loose connective tissue and adipose
• How does the adventitia differ from the serosa?

  Adventitia has no mesentery if retroperitoneal
• What is the primary function of the esophagus?

  Transports masticated material to the stomach
• What type of epithelium lines the esophagus?

  Stratified squamous non-keratinizing epithelium
• What is the structure of the muscularis in the esophagus?

  Skeletal upper third, mixed middle third, smooth lower third
• What is the stomach's role in digestion?

  Storage and chemical breakdown of food
• What happens to the rugae when the stomach distends?

  They disappear as the stomach fills
• What is chyme?

  Mixture of food and gastric juices
• What are the components of the gastric pit?

  • Mucous cells
  • Parietal cells
• What are the components of the gastric gland?

  • Enteroendocrine cells
  • Chief zymogenic cells
• What is the primary function of the small intestine?

  Completes digestion and absorbs nutrients
• What is the surface area of the small intestine?

  250 m²
• What structures increase the surface area of the small intestine?

  • Plicae circulares
  • Villi
  • Microvilli
• What are plicae circulares?

  Circular ridges projecting into the gut lumen
• What are villi?

  Finger-like structures from plicae circulares
• What type of epithelium lines the villi?

  Simple columnar epithelium
• What are the four types of cells found in villi?

  Enterocytes, goblet cells, paneth cells, enteroendocrine cells
• What are microvilli?

  Microscopic finger-like structures on enterocytes
• How long is the duodenum?

  25 cm
• What does the duodenum receive from the gall bladder?

  Bile and digestive enzymes
• What is the function of Brunner’s glands?

  Secrete alkaline mucus to counteract acidity
• How long is the jejunum?

  2.5 m long
• What is the primary role of the jejunum?

  Majority of nutrient absorption occurs
• How long is the ileum?

  3.6 m long
• What is the function of Peyer’s patches in the ileum?

  Responsible for immune surveillance
• What are crypts of Lieberkuhn?

  • Tubular glands between villi
  • Produce various epithelial cells
• What type of cells are produced in the crypts of Lieberkuhn?

  Enterocytes, goblet cells, paneth cells, enteroendocrine cells
• How long is the large intestine?

  1.5 m long