alimentary canal

• alimentary canal or gastrointestinal tract

  a muscular tube that winds down from the mouth to the anus

  digests food and absorbs through the linings into the blood
• alimentary canal consists of...

  mouth, pharynx, esophagus, stomach, small intestine and large intestine, anus
• Alimentary canal is 9 m long but shorter in body because of muscle tone
• Food material is technically outside of the body because canal is open to the external environment
• visceral peritoneum

  covers external surfaces of most digestive organs
• parietal peritoneum

  line the body wall
• peritoneal cavity

  between the two peritoneum is a space containing serous fluid

  • allows organs to move and slide easily
• mesentery

  double layer of peritoneum that hangs the organs off the body wall

  • provides routes for blood vessels, lymphatics and nerves to reach digestive viscera and stores fat
• most times mesentery attaches dorsally and then to the posterior wall but there are ventral ones
• retroperitoneal organs

  don't keep their mesenteries
• intraperitoneal or peritoneal organs

  keep their mesentery and remain in the posterior cavity
• mucosa or mucous membrane

  moist, epithelial membrane that lines alimentary canal lumen

  • secrete mucus, digestive enzymes, and hormones
  • absorb the end products of digestion into the blood
  • protect against infectious disease
• Mucosa has three layers

  • lining epithelium
  • a lamina propria
  • muscularis mucosae
• Epithelium lining of mucosa

  made up of simple columnar in rich mucus-secreting cells

  • mucus protects organs from being eaten up and helps food move along

  exceptions are the mouth, esophagus and anus where it's stratified squamous
• lamina propriaof mucosa

  consists of reticular connective tissue and nourishes the epithelium and absorbs nutrients

  • has isolated lymphoid follicle that protect us from bacteria that have easy access to digestive tract
• muscularis mucosaeof mucosa


  layer of smooth muscle that helps move food along; adhancing absorption and secretion
• submucosa

  areolar connective tissue with many blood and lymphatic vessels, lymphoid follicles and nerve fibers that supply GI tract

  • has many elastic fibers that let stomach snapback
• muscularis externa or muscularis

  layer responsible for segmentation or peristalsis

  • has inner circular layer and outer longitudinal layer of smooth muscle
• Sometimes circular layer of muscularis will thicken forming sphincters

  • valve-like that control food going into one organ and have no backflow
• serosa in intraperitoneal organs

  is just the visceral peritoneum
• serosa in most alimentary canal organs

  is formed of areolar connective tissue covered mesothelium, a single layer of squamous epithelial cells
• serosa in the esophagus

  serosa is replaced with adventitia

  • just an ordinary dense connective. tissue that binds the esophagus to surrounding structures
• serosa in retroperitoneal organs

  have both adventitia and serosa

  • adventitia on the side facing the dorsal body wall
  • serosa on the side facing the peritoneal
• Splanchnic circulation


  arteries that branch off of the aorta that serve digestive organs

  • Hepatic, splenic, and left gastric arteries
  • Inferior and superior mesenteric arteries
• Hepatic portal circulation

  drains nutrient filled blood from the organs

  • delivers this blood to the liver to be processed
• label the layers of the stomach

  A) mucosa

  B) submucosa

  C) muscularis externa

  D) subserosa

  E) serosa

  
• The adventitia is the serous membrane that lines the muscularis externa of the oral cavity, pharynx, esophagus, and rectum.
• The visceral peritoneum is the serous membrane that lines the stomach, large intestine, and small intestine.
• The mesentery is an extension of the visceral peritoneum that attaches the small intestine to the rear abdominal wall.
• The mesocolon is an extension of the visceral peritoneum that attaches the large intestine to the rear of the abdominal wall.