Visceral Anatomy and Histology - The GI tract Flashcards
where is the lesser omentum
extends from the lesser curvature of the stomach and proximal duodenum -> to the inferior aspect of the liver
what are the clinically important structures that lie within the lesser omentum?
- hepatic artery
- common bile duct
- hepatic portal vein
what is the mesentery?
double-fold of small intestinal peritoneal lining continuous with the serosa
- lines the jejunum and ileum, binds them to the posterior abdominal wall
what helps keep the small intestine from being “tangled”
mesentery
what is mesocolon
2 separate double-folds that connect the transverse and sigmoid colon to the posterior abdominal wall
what divides the liver into left and right lobes and attaches to the anterior abdominal wall
the falciform ligament
what bursa is behind the stomach and lesser omentum?
omental bursa
the arteries branch off the abdominal aorta at 3 major sites:
- celiac trunk
- superior mesenteric artery
- inferior mesenteric artery
celiac trunk gives rise to?
- left gastric artery
- common hepatic artery
- splenic artery
- pancreas
- liver
- gallbladder
- stomach
- duodenum
- spleen
which branch of arteries from the abdominal aorta supplies the structures of the embryologic foregut
celiac trunk
superior mesenteric artery gives rise to arteries that supply:
- pancreas
- stomach
- small intestine
- as well as the large intestine up to the point of the transverse colon
which branch of arteries from the abdominal aorta supplies the structures of the embryologic foregut and midgut
superior mesenteric artery
inferior mesenteric artery gives rise to arteries that supply:
the rest of the large intestine and superior anus (embryonic hindgut)
venous circulation is a ?
portal circulation
what is a portal circulation?
capillary networks that are in series with each other
the inferior mesenteric vein joins with the ?
splenic vein
the splenic vein and the superior mesenteric vein come together to form the ?
hepatic portal vein
the hepatic portal vein carries ? but ? to the ? from most of the organs within the abdominal cavity
poorly-oxygenated
nutrient-rich blood
liver
what are the layers of the GI tract? (from lumen to outer wall)
- mucosa
- submucosa
- muscularis
- serosa/adventitia
describe the mucosa
absorption, secretion, chemical digestion, many endocrine functions, some immune functions
describe the submucosa
secretion, lots of blood vessels, contains a large plexus of neurons (submucosal or Meissner’s plexus), some immune functions
describe the muscularis
two to three layers of smooth muscle, main function is propulsion, another large neuronal plexus exists here (muscular or Auerbach’s plexus)
describe the serosa/adventitia
connective tissue that anchors the GI tract and at the same time allows mobility – forms the peritoneum
the epithelial lining consists of:
- epithelium
- goblet cells
- enteroendocrine cells
goblet cells secrete ? which protects/lubricates the GI tract, forms a water layer for diffusion of nutrients, and helps “store” ?
mucous
IgA
what forms the border between the mucosa and submucosa
muscularis mucosa
enteroendocrine cells (DNES) can be ? or ?
open or close
open enteroendocrine cells?
contact the lumen and can sense luminal contents
closed enteroendocrine cells?
do not contact the lumen, thus they are dependent on other sources of input to regulate secretion
where are G cells found?
stomach
G cell = what hormone ?
gastrin
what does gastrin mainly do?
increases secretion of stomach acid
where are I cells found?
small intestine
I cell = what hormone?
CCK
what does CCK do?
pancreatic enzyme secretion, gallbladder contraction
where are Mo cells found?
small intestine
Mo = what hormone?
Motilin
what does motilin do?
migrating motor complex
S cells are found where?
small intestine
S cells = what hormone?
secretin
what does secretin do?
bicarobonate and water secretion from pancrease
inhibits gastric acid secretion and gastric emptying
what is MALT
smaller nodules rich in macrophages and lymphocytes, found in the mucosa (lamina propria)
what is Peyer’s patches
very large (extends right through to the submucosa) nodules that may be cm in length
○ found mostly throughout the distal small intestine (jejunum, ileum)
in the epithelium overlying Peyer’s patches are ?
M cells
what do M cells do?
selectively endocytose antigens and present them to dendritic cells and lymphocytes
esophagus has an ?
adventitia
what forms the outer layer of the GI tract?
serosa
in terms of the peritoneal membrane and peritoneal fluid, small particles are absorbed by ? and enter the portal circulation
venous pores
in terms of the peritoneal membrane and peritoneal fluid, large particles are absorbed by ? and enter the thoracic duct
lymphatic capillaries
The trunk is bounded by what superiorly?
Diaphragm
the trunk is bounded by what anterolaterally
musculo-aponeurotic walls
the trunk is bounded virtually by what inferiorly
the pelvic inlet
the trunk is bounded by what posteriorly
the vertebrae
what does the alimentary canal contain
- lower esophageal sphincter, stomach
- duodenum, jejunum, ileum
- Cecum, ascending colon, transverse colon, descending colon
what are some accessory organs
liver, gall bladder, pancreas, spleen, kidneys
