Anatomy of the Lower GI system Flashcards
At what level does the oesophagus pierce the diaphragm?
T10
Describe the abdominal and pelvic cavity?
The abdominal cavity and pelvic cavity are continuous with each other, only separated by peritoneum (roof of pelvic cavity).
What is peritonitis?
Inflammation of the peritoneum caused by infection from surgery or trauma - leads to guarding
Describe the peritoneum?
Continuous membrane which secretes lubricating peritoneal fluid into the peritoneal cavity
Lines the abdominal cavity and invests viscera
Describe the visceral and partial peritoneum?
Visceral - invests an orga
Parietal - touches the enteral body wall
What is retroperitoneal?
Lays posterior to the peritoneum - behind
What are the retroperitoneal organs?
Kidneys Adrenal gland Pancreas Parts of small intestine Parts of large intestine
What are the pelvic organs of the GI tract?
Rectum
Anal canal
Anus
Where is the stomach mostly located?
in the left lower quadrant
What is the small intestine attached to the body wall by?
A mesentery
What are the parts of the small intestine?
Duodenum
Jejunum
Ileum
What is the mesentery?
A double layer of peritoneum
Connects intraperionteal organs to the body wall
What parts of the large intestine are retroperitoneal?
Ascending and descending colon are retroperionteal
What is peristalsis?
waves of SIMULTANEOUS shortening of the length of a segment of the tube PLUS narrowing of the luminal diameter in that segment
describe what the outer longitutal layer and the inner circular layer of the walls of the intestine do?
Outer longitudinal - smooth muscle - shortens the tube
Inner circular - smooth muscles - constricts (narrows) the diameter
What is the mucosa like in the oral cavity, oesophagus and anus?
Protective - areas of greatest mechanical friction
What is the mucosa like in the stomach?
Secretory - minimally absorptive
What is the mucosa like in the small intestine and large intestine?
Absorptive
Name the sphincter at the junction between laryngopharynx & oesophagus to help prevent regurgitation?
Cricopharyngeal sphincter
Name the sphincter at the junction between stomach & duodenum to control the release of chyme from the stomach?
Pyloric sphincter
Name the sphincter at at the junction between anus & external environment to control the release of stool from the anal canal?
External anal sphincter
What are anatomical sphincters?
are discrete areas where muscle completely encircles the lumen of the tract
Can be composed of smooth or skeletal muscle
Describe the track of the IVC in the abdomen?
It ascend in the retroperitoneum then passes through the diaphragm into the right atrium
Describe the track of the aorta in the abdomen?
The Aorta leaves the left ventricle passes through the diaphragm the descends in the retroperitoneum
What are the 3 midline branches of the abdominal aorta from superior to inferior?
Coeliac trunk
Superior mesenteric artery
Inferior mesenteric artey
What do the 3 midline branches supply?
Coeliac trunk - foregut organs
Super mesenteric artery - midgut organs
Inferior mesenteric artery - hindgut organs
Describe the venous drainage to the abode organs, what drains each section?
Foregut - splenic vein
Midgut - Superior mesenteric vein
Hindgut - inferior mesenteric vein (drains hindgut via splenic vein)
What do all the veins join up to form and take to the liver?
The hepatic portal vein
What is the hepatic portal vein formed by?
The splenic vein and the superior mesenteric artery
Describe the portal venous system?
Drains from absorptive parts of GI tract and associated organs to the liver via hepatic portal vein
This blood de-oxygenated and nutrient-rich
Describe the systemic venous system?
Drains de-oxygenated blood from the rest of the body to the right atrium of the heart.
Include blood from the liver via hepatic veins
Describe where foregut structures drain their lymph via?
Via nodes located along the splenic artery towards the coeliac nodes (located around the origin of the coeliac trunk)
Describe where midgut structures drain their lymph via?
Via nodes located along the superior mesenteric artery towards the superior mesenteric nodes (located around the origin of the superior mesenteric artery)
Describe where hindgut organs drain their lymph via?
Via nodes located along the inferior mesenteric artery towards the inferior mesenteric nodes (located around the origin of the interior mesenteric artery)
What is the body response to obstruction of the GI tract?
increased peristalsis proximal to the site of the obstruction in an attempt to remove it
Why might a patient experience colicky pain?
Because peristalsis occurs in waves so the pain will come and go as the body tried to get over the obstruction
