The Digestive System Flashcards
(22 cards)
The gut contains what “system?”
the enteric nervous system
ie the “gut brain” with over 500 million neurons
The enteric system has reflex circuits that act autonomously and are split into what 2 layers?
1) myenteric plexus = regulates gut motility
2) submucosal plexus = regulates enzyme secretion, blood flow, water/ion balance
What are the 4 cells of the stomach and where do they reside?
1) mucous cells
2) chief cells
3) parietal cells
4) g cells
all are found within gastric pits
What is the role of mucous cells?
lubricate the stomach wall, which provides protection from the low pH
What is the role of the chief cells?
secretes pepsinogen, which in the presence of HCl, is converted to pepsin
*pepsin begins protein breakdown
What is the role of parietal cells?
releases HCl and intrinsic factor, which allows the ileum to absorb B12
What is the role of g cells?
releases gastrin, which in turn stimulate the parietal cells to secrete HCl
What are the segments of the small intestine?
duodenum, jejunum, ileum
What two types of digestion occur in the mouth?
physical and chemical
True or False - protein digestion occurs in the mouth
False - only carbohydrate digestion through amylase occurs in the mouth
Most digestion occurs here
the duodenum
What initiates protein breakdown in the small intestine?
Enterokinase, which converts trypsinogen into trypsin
What is the role of cholecystokinin, CCK?
it stimulates the gallbladder to release bile in the presence of fat b/c gut motility decreases
What is secretin?
stimulates the pancreas to release HC03 as a buffer due to the extreme acidity of the chyme arriving from the stomach
Where does most of the nutrient absorption occur in the body?
in the jejunum, via villi lacteals
What is the function of the ileum?
to complete any remaining absorption
What is the cecum?
a small pouch containing the appendix that connects the ileum to the ascending colon
What connects the small and large intestine?
the cecum, via the ileocecal valve
What are the segments of the large intestine?
1) ascending colon
2) transverse colon
3) descending colon
4) sigmoid colon
5) rectum
What are the functions of the large intestine?
water absorption, breakdown of fiber via e.coli, source of vitamin K, riboflavin, thamine
What are the portions of the anus?
1) internal anal sphincter - smooth muscle (involuntary)
2) external anal sphincter - skeletal muscle (voluntary)
How does bile empty from the gallbladder into the small intestine?
via the Sphincter of Oddi
