Stomach and Small Intestine Flashcards
what is the stomach
a j-shaped organ between the esophagus and small intestine
4 functions of the stomach
- temporary storage of ingested food
- mechanical breakdown of food
- chemical digestion of food by acid and enzymes
- production of intrinsic factor for the absorption of B12
4 regions of the stomach
cardia, fundus, body, pylorus
cardia
small area near the esophgeal sphincter
fundus
balloons above the cardia serving as temporary storage
body
main portion of the stomach
pylorus
inferior end of the J connects the stomach to the small intestine; regulates the flow of chyme through the pyloric sphincter
what is special about the stomach wall
there is an extra layer of smooth muscle in the muscularis
function of stomach wall specialization
provides additional strength and churning ability
rugae
numerous folds that flatten as the stomach fills
rugae function
allows for greater mechanical friction and more volume (1.5 L)
max stomach content
4 L
stomach wall tissue
simple columnar epithelia and mucous lining
gastric pits
depressions allowing for secretion of alkaline mucous
gastric pits in the fundus
juices are secreted from deeper gastric glands
4 types of secretory epithelia
- goblet cells
- parietal cells
- chief cells
- g cells
goblet cells
secrete alkaline mucous that protects and lubricates
parietal cells
secrete HCL and intrinsic factor
predominant glandular cell in the body of the stomach
parietal cells
chief cells
secrete pepsinogen
how is pepsin created
combination of pepsinogen and HCL
chief cells location
fundus
g cells
secrete gastrin which triggers HCL secretions
g cells location
pylorus
how much absorption happens in the stomach
little to none
purpose of alkaline mucous
offsets the acidity of chyme
how often does the migrating motor complex occur
every 1.5 - 2 hours
stomach ulcers
open sores in the mucosal and submucosal lining of the stomach
what can cause stomach ulcers
- H. pylori (bacteria)
- stress aggravated
- smoking and drugs
how are stomach ulcers treated
antibiotics and antacids
small intestine
the longest section of the alimentary canal responsible for the most absorption
cholecystokinin
a hormone released into the small intestine to slow gastric motility of chyme
how long does chyme stay in the small intestine
3-10 hours
3 sections of the small intestine
duodenum, jejunum, ileum
duodenum
- receives chyme from the stomach
- receives secretions from the liver and pancreas via pancreatic and common bile ducts
jejunum
40% of the small intestine
ileum
- connects to the large intestine via the cecum
- 60% of the small intestine
how is the small intestine suited for absorption
- transverse mucosal folds
- villi
how is the small intestine suited for absorption
- transverse mucosal folds
- villi
- microvilli
villi
- projections from the mucosa into the lumen covered with epithelia
- each contains its own blood and lymphatic capillaries and nerve fiber
villi
- projections from the mucosa into the lumen covered with epithelia
- each contains its own blood and lymphatic capillaries and nerve fiber
what is the epithelium of the villi
simple columnar cells
microvilli
further increase surface area for maximal absorption
secretions of enzymes for continued digestion
- peptidases
- sucrase/maltase/lactase
- intestinal lipase
peptidases
splits peptide chains into amino acids
sucrase/maltase/lactase
contines carbohydrate reduction to monosaccharides
intestinal lipase
splits lipids into fatty acid and glycerol
what controls secretions of the small intestine
parasympathetic nervous system and hormones
where are intestinal glands and secretions found
the valleys between villi
what do intestinal glands secrete
a watery pH neutral fluid to dissolve nutrients for absorption
pH of chyme
2 (acidic)
mesentery
double fold of mucosa
mesentery job
anchor blood vessels and nerves
