Lectures 18-19: Small Intestine, Colon, and Rectum Flashcards
Where are a) nutrients and water extracted from the chyme for use in the body and b) excess waste is excreted?
Small intestine
Another name for small intestine
small bowel
Where are most of the absorption of water and nutrients absorbed?
small intestine
What are the divisions of the small intestine?
in this order, the duodenum, jejunum, and ileum
Where does the SI start and end?
pylorus and ends at the ileocecal valve
What does duodenum mean?
“12”
where does the duodenum run from?
pylorus to the ligament of Treitz
what type of organ is the duodenum?
retroperitoneal organ
what does jejunum mean?
“empty”
Where does the jejunum run from?
Ligament of Treitz to the mid-small bowel
What does the jejunum have, structural-wise?
Muscular folds called plicae circulares
What type of organ is the jejunum?
Intraperitoneal organ
What does ileum mean?
“twisted”
The ileum runs from the…
mid-small bowel to the ileocecal valve at the colon
What type of organ is the ileum?
intraperitoneal organ
what is prominent in the ileum
The plicae circulares in the upper to mid-ileum
why is plicae circulares prominent in the ileum
plicae circulares increases surface area and corkscrews the motion of the chyme
what supplies the duodenum with blood?
gastroduodenal artery and branches of the superior mesenteric artery
what supplies the jejunum with blood?
jejunal branches of the superior mesenteric artery
what supplies the ileum with blood?
ileal, right colic, ileocolic, and appendiceal branches of the superior mesenteric artery
what does villus mean?
“tuft of hair”
what do the villus do?
they are used for absorption
what do villus have on their surface?
microvilli that form the brush border
where are intestinal glands located?
the crypts of Lieberkuhn
what do the intestinal glands do?
secrete intestinal juices
what are paneth cells?
in the deepest part of glands; secrete lysozyme (bactericidal enzyme); are phagocytes
what are enteroendocrine glands?
the deepest part of gland; cells secrete secretin (S-cells), CCK (CCK-cells), and gastric inhibitory peptide (K-cells)
what are Brunner’s glands
lie in the deepest part of duodenal mucosa; secrete alkaline mucous which neutralizes acid
what are Goblet cells
cells that secrete mucous
what patch detects foreign elements in what
Peyer’s patches in lymphatic tissue that detect foreign elements in the GI tract and signal the immune system
what part of the colon receives chyme from what
Cecum; terminal ileum
what guards the cecum from what and why
a fold of mucosa in ileocecal valve to prevent backflow of the feces into the SI
what supplies the right colon with blood?
right colic arteries of the superior mesenteric artery
what does SMA stand for?
superior mesenteric artery
what supplies the transverse color with blood?
middle colic artery of SMA
what supplies the descending colon with blood?
left colic branches and arcades of the Drummond of the inferior mesenteric artery
what does IMA stand for?
inferior mesenteric artery
what supplies the sigmoid colon with blood?
sigmoid arteries of IMA
-tome
“to cut”
-tomy
“to remove by cutting”
-otomy
“to cut open with intent of closing the wound
-ostomy
“cut open permanently or semipermanently”
what is the greater omentum mostly made of
fat
what functions does the greater omentum do?
stores fat and supplies the stomach with blood
what does the lesser omentum carry?
vessels that go to the stomach and liver
two processes of the SI
digestion and absorption
how long does it take for food to move through the SI
4-6hrs
what activity moves chyme through the SI
peristalsis
what continues breaking down food in the SI
three pancreatic enzymes: trypsin, chymotrypsin, and elastase
what is fistulas
bile leakage
what breaks proteins down?
pepsin from stomach
what splits lipids into monoglycerides
pancreatic lipase
what splits carbs into sugars
pancreatic amylase
maltose
glucose times 2; split maltase
sucrose
glucose + fructose, split by sucrase
lactose
glucose and galactose, split by lactase
how much nutrition is absorbed in the SI
90-95%
What is absorbed in the SI?
Carbs (monosaccharides), proteins, and lipids
common types of monosaccharides in SI
glucose, fructose, and galactose
common types of proteins in SI
amino acids, dipeptides, and tripeptides
common types of lipids
fatty acids, monoglycerides, and glycerol
what results from an intake of too much liquids?
drop in sodium and electrolytes. Can cause death
what signals distension?
myenteric plexus
what impulses increase motility and secretion
sympathetic impulses
what stimulates secretion?
vasoactive peptide (VIP)
another name for colon
large intestine (LI)
Main jobs of rectum, anus, and colon
absorbing water; storing; elimination of waste
what is mass peristalsis
the gastrocolic reflex moving the chyme through the colon
what is the only function of the LI
absorping water
what is gas mostly?
swallowed air
what makes the feces
water, salts, desquamated epithelial cells, bacterial decay products and undigested food
