Bi 122 Ch. 14

Anus

Opening of the large intestine, external sphincter voluntary control, internal smooth muscle sphincter involuntary.

Esophagus A and P:

10in. long runs from pharynx to stomach through the diaphragm. Conduct food by peristalsis(slow rhythmic squeezing) (KNOW this) passage way for food only.

Colon:

Ascending up the right side of the abdomen transverse across and descends down left side Sigmoid enters pelvis. Rectum and Anus located pelvis.

Chemical digestions

Begins in sm. intestine> enzymes are produced by intestinal cells and pancreas, Pancreatic ducts carry enzymes to the sm. intestine, Bile formed by the liver enters via bile duct.

Colon

DACS, Descending, Ascending, Cecum, Sigmoid.

Subdivisions of Sm. Intestine

DJI

Small intestine:

DJI: Duodenum, Jejunum, ileum,

Layers of tissue in the Alimentary Canal:

For layers of tissue from deep to superficial: Mucosa: innermost moist membrane, surface epithelium, sm. amount of connective tissue, sm. smooth muscle layer, lines the cavity. Submucosa:contains glands that secrete mucous, as well as, lymphoid tissue and lymphatic. Muscularis externa: smooth muscle inner circular, outer longitudinal Serosa: contains fluid producing cells: Made up of Visceral peritoneum and Parietal peritoneum.

Alimentary canal:

Gi tract continuous coiled hollow tube, these organs ingest, digest, absorb defecate.

The digestive system functions:

Ingestion: take in food Digestion: break it down Absorption: movement of nutrients into the bloodstream Defecation: rids the body of indigestible substances.

Stomach Anatomy cont.

Know that omentum is the layer of fat and peritoneum hangs down in front. Greater omentum: embedded fat insulates cushions and protects abdominal organs, lymph follicles contain macrophages. Mucularis externa has a third layer Oblique that helps to churn and pummel the food.

Lg. Intestine

Larger in diameter, shorter in length. Extends from the ileocecal valve to the anus: Subdivisions: Cecum: saclike first part of the lg. intestine Appendix: Accumulation of lymphatic tissue, hangs from the cecum. Colon: Three parts L to R breakfast(ascending), lunch(transverse), and dinner(descending) and sigmoid the S that enters the pelvis. Rectum Anal canal.

Mouth

Lips,, cheeks, hard palate, soft palate, uvula, vestibule(space between lips externally and teeth and gums), oral cavity proper(area contained by the teeth), tongue(attached to hyoid bone and styloid processes, tonsils, palatine located at the posterior end of oral cavity, Lingual located at the base of the tongue.

Stomach Anatomy

Located on the left side of the abdominal cavity. Food enters through the: cardioesophageal sphincter, food empties into sm. intestine at pyloric sphincter Rugae: internal folds of the mucosa (stretches to 1 gallon) External regions

Sm. Intestine anatomy:

Microvilli (brush border), Villi, circular folds

Organs of the alimentary canal

Mouth, pharynx, esophagus, stomach, sm. intestine, lg. intestine, anus.

Lg. intestine Anatomy

No villi, goblet cells produce alkaline mucus which lubricate passage of feces. Muscularis externa layer is reduced three bands of muscle called teniae coli (won't be tested on teniae coli) Cause the wall to pucker into haustra pocket-like sacs.

Structure of Stomach Mucosa

Produce sticky alkaline mucus, contain gastric glands in gastric pits secrete gastric juice, Chief cells produce protein digesting enzymes, Parietal cells are puffy pink and produce hydrochloric acid, Enteroendocrine cells produce gastrin.

Function/Physiology of the Stomach

Store food, breaksdown food, chemical breakdown of protein begins, delivers chyme to the sm. intestine.

Two nerve plexuses serve alimentary canals:

Submucosal nerve plexus, Myenteric nerve plexus. Wor

Small Intestine

The body's Major digestive organ, site of nutrient absorption into the blood, muscular tube extending from the pyloric spincter to the ileocecal valve (sm. intestine to lg.) suspended from the posterior abdominal wall by the mesentery.

Pharynx physiology:

food is propelled to the esophagus by two muscle layers: longitudinal inner layer/circular outer layer. Food movement is by alternating contractions of the muscle layers (peristalsis)

Pharynx anatomy:

nasopharynx(not part of digestive sys.) oropharynx posterior to oral cavity, laryngopharynx below oropharynx.

Accessory digestive organs:

teeth, tongue, and more