GI- Lecture 1 Flashcards
2 main groups of organs in the Digestive system
- alimentary canal (GI tract)
- accesory digestive organs
Organs part of the Alimentary canal
- mouth
- pharynx
- esophagus
- stomach
- small intestine
Organs part of the accessory digestive organs
- teeth
- tongue
- gall bladder
- salivary glands
- liver
- pancreas
Functions of the alimentary canal
- digests food
- absorbs digested fragments through lining into the bloodstream
- excretes end products of digestion
The function of accessory digestive organs
produce secretory products like bile, enzymes, and saliva to help digest food
What lines the abdominopelvic cavity
serous membranes like the peritoneum
Types of peritoneum
- Visceral peritoneum: covers the external surface of digestive organs
- Parietal peritoneum: lines the walls of the abdominal cavity
visceral is continuous with the parietal
What is the Peritoneal cavity
slit-like space btwn the visceral and parietal peritonea
What is the Mesentary
fused double layer of the parietal peritoneum
Function of the Mesentary
- holds organs in place
- carries blood vessels, lymphatic vessels, and nerves to the organs of the GI tract
Peritoneal organs vs retroperitoneal organs
- peritoneal organs: organs with a mesentery that stay in the peritoneal cavity
- retroperitoneal: organs that lost their mesentery and lie posterior to the peritoneal cavity
Splanchnic circulation
includes arteries that branch off the abdominal aorta to the digestive circulation & the hepatic portal circulation
Arteries & the organs they serve
hepatic artery—> liver
gastric artery—> stomach
splenic artery—> spleen
superior & inferior mesenteric artery—> small and large intestines
how much of the cardiac output do arteries get
1/4, increases after you eat
Where does the venous return go through from most of the abdominopelvic region
inferior vena cava
* venous return from digestive viscera (organs) is indirect through the hepatic portal circulation
Hepatic portal circulation
veins coming from various organs, join up with the hepatic portal vein and empty into the liver
Typical 4 layers of the GI tract
- muscularis externa
- submucosa
- serosa
- mucosa
Mucosa
- innermost, secretes mucus, digestive enzymes, and hormones
- absorbs the end product of digestion and protect the tract against infection
3 sublayers of Mucosa
- surface epithelium: columnar epithelia + goblet cells; secrete enzymes and hormones in stomach and small intestine
- lamina propria: loose connective tissue with isolated lymph nodes; some bunches of these nodules are in key areas (tonsils, appendix)
- muscularis mucosa: a thin layer of smooth muscle; responsible for local movements and causes mucosa to form folds in the small intestine
Submucosa
- moderately dense connective tissue
- contains blood, lymphatic vessels, lymph nodes, and nerve fibers
- elastic, allows stomach to regain shape after large meal
Muscularis externa
- responsible for the mixing and propulsive movements of the GI
- inner circular layer + outer longitudinal layer
- thickens to form sphincters at organ-organ junctions
Serosa
- outermost, protective layer (visceral peritoneum)
- loose CT covered by single layer of squamous epithelial cells
What surrounds the esophagus
surrounded by adventitia (fibrous CT that binds esophagus to surrounding tissues) instead of serosa
What do retroperitoneal structures have
both a serosa on the side facing the peritoneal cavity & an adventitia on the side against the dorsal body wall
