Small Intestine and Large Intestine Flashcards
What regulates and coordinates numerous GI tract activities?
enteric nervous system
What are the activities that the enteric nervous system regulates and controls?
- gastric secretory activity
- GI blood flow
- peristalsis
Where is the ENS located?
between the walls of the GI tract
What is generally independent of CNS and receives input from sympathetic and parasympathetic innervation?
ENS
What is the sympathetic abdominal innervation and associated levels?
- greater splanchnic (T5-T9)
- lesser splanchnic (T10-T11)
- least splanchnic (T12)
- lumbar splanchnic (L1-L2/L3)
The greater splanchnic nerves run to the (1) ganglion which distribute to the (2)
- celiac
- foregut
The lesser and least splanchnic nerves run to the (1) and (2) which distribute to the (3)
- superior mesenteric ganglion
- aorticorenal ganglia
- midgut
The lumbar thoracic splanchnic nerves run to the (1) which distribute to the (2)
- inferior mesenteric ganglion
- hindgut
The celiac, superior mesenteric, aorticorenal, and inferior mesenteric plexus communicate via what?
intermesenteric plexus
What is the parasympathetic abdominal innervation and associated postganglionic distribution?
- vagus n. (CN X) - foregut and midgut
- pelvic splanchnic (S2-S4) - hindgut
Descending sympathetic innervation to the pelvic organs is via what plexuses?
superior hypogastric plexuses
What receives pelvic splanchnic nn. (parasympathetics)?
hypogastric nn (inferior hypogastric plexus)
What are the sympathetic activities of the abdominal organs and what do they go to?
- vasoconstriction
- decreased peristalsis
- decreased hormonal secretion
- goes to smooth muscle and glands
What are the parasympathetic activities of the abdominal organs and what do they go to?
- vasodilation
- increased peristalsis
- increased hormonal secretion
- goes to smooth muscle and glands
Pre-synaptic sympathetic fibers synapse directly into what?
suprarenal gland
What travels with sympathetic fibers (GSA)
pain (GVA)
What is the function of the small intestine?
absorption of nutrients
What are the parts of the small intestine?
- duodenum
- jejunum
- ileum
What does the small intestine extend from?
from pylorus to ileocecal junction
What do the jejunum and ileum contain that increase surface area for absorption?
elaborate folds of mucosa
What part of the small intestine doesnāt absorb any nutrients?
duodenum
What vertebral levels does the duodenum travel from?
L1 to L3
How many parts of the duodenum are there and what are their associated vertebral levels?
- 1st: superior part (L1)
- 2nd: descending part (L2-L3)
- 3rd: horizontal part (L3)
- 4th: ascending part (L3)
What is the most movable part of the duodenum?
superior part (first)
What is the very first part of the duodenum called?
duodenal cap (ampulla)
What attaches the superior part (1st part) of the duodenum to the porta hepatis of the liver and what is contained in it?
hepatoduodenal ligament:
- portal triad
**common bile duct
**hepatic artery
**portal vein
What parts of the duodenum are retroperitoneal?
the 2nd and 3rd part
What part of the duodenum attaches to the pancreas?
2nd part
What is located in the 2nd part of the duodenum and is where the bile duct + main pancreatic duct connect to the duodenum and drain into?
hepatopancreatic ampulla
What is the landmark located halfway along the second part of the duodenum that marks the transition from foregut to midgut?
hepatopancreatic ampulla (ampulla of Vater)
The hepatopancreatic ampulla connects to the duodenum via what?
major duodenal papilla
What is the opening of the accessory pancreatic duct into the 2nd part of the duodenum?
minor duodenal papilla
What part of the duodenum is important for the hepatobiliary tract?
2nd part of the duodenum
What does the 3rd part of the duodenum run in front of?
IVC and aorta
What runs in front of the 3rd part of the duodenum?
superior mesenteric vessels
What is the duodenojejunal junction?
where the 4th part of the duodenum meets and continues as the jejunum
What is a thin band of tissue that connects the duodenojejunal junction to the right crus of the diaphragm?
ligament of Treitz
What is the ligament of Treitz critical in ruling out?
malrotation of the gut in children
A GI bleed above the ligament of Treitz will lead to (1)
vomiting up blood
A GI bleed below the ligament of Treitz will lead to (1)
dark, tarry, maybe purplish stool
What two arteries supplies the duodenum and what does this mark the transition of?
- celiac trunk via gastroduodenal a
- superior mesenteric artery via inferior pancreaticoduodenal a
marks transition between foregut and midgut
What branches off the gastroduodenal artery to supply the upper portion of duodenum and head of pancreas?
ant. and post. superior pancreaticoduodenal a
What branches off the superior mesenteric artery and supplies the lower portion of the duodenum?
ant. and post. inferior pancreaticoduodenal a
What is the direct venous drainage of the duodenum?
hepatic vein
What is the indirect venous drainage of the duodenum?
- superior mesenteric vein
- splenic vein
The anterior lymphatic vessels of the duodenum drain into the (1) located alone the superior and inferior pancreaticoduodenal arteries and into the (2) which lie along the gastroduodenal artery, and then drains into (3)
- pancreaticoduodenal lymph nodes
- pyloric lymph nodes
- celiac lymph nodes
The posterior lymphatic vessels of the duodenum pass posterior to the head of the pancreas and drain into the (1); efferent lymphatic vessels from the duodenal lymph nodes drain into the (2)
- superior mesenteric lymph nodes
- celiac lymph nodes
What is the parasympathetic innervation of the duodenum?
vagus n
What is the sympathetic innervation pathway of the duodenum?
- spinal cord T5-T11
- greater and lesser splanchnic
- celiac and superior mesenteric plexuses
- peri-arterial plexuses extending to pancreaticoduodenal aa
- duodenum
What does the jejunum begin at and what part of the small intestine is considered the jejunum?
- begins at duodenojejunal flexure
- proximal 2/5 of intestine
Where does the ileum end at and what part of the small intestine is considered the ileum?
- ends at ileocecal junction
- distal 3/5 of intestine
What keeps the jejunum and ileum attached to the posterior abdominal wall?
mesentery
What is the function of the jejunum?
lipid and protein digestion
What are in the jejunum but not in the ileum?
plicae circulares
How does the jejunum differ from the ileum?
- thicker walls
- larger diameter
- arteries
What is the function of the ileum?
absorption of most digested nutrients
What has peyerās patches?
ileum
How does the ileum differ from the jejunum?
- thinner walls
- smaller diameter
- arteries
What is the caliber of the jejunum in relation to the ileum?
jejunum : greater
ileum : lesser
What is the plicae of the jejunum in relation to the ileum?
jejunum : many
ileum : few