Digestive tract organs
mouth -> esophagus -> stomach -> small intestine -> large intestine
mouth
Chews and mixes food with saliva. Saliva helps breakdown and moisten food particles. Chemical digestion with carbohydrate breakdown. Mechanical digestion with chewing.
esophagus
Tube that passes food from mouth to stomach. Peristalsis, or wavelike movement, pushes food down the tube. Epiglottis helps prevent choking.
stomach
A muscular, elastic, pouchlike organ of the digestive tract that grinds and churns swallowed food and mixes it with acid and enzymes, forming chyme. Mechanical breakdown of food by grinding, churning, mixing. Chemical breakdown of food by release of gastr
chyme
fluid resulting from the actions of the stomach upon a meal
small intestine
20 foot length of small-diameter intestine, below the stomach and above the large intestine, that is the major site of digestion of food and absorption of nutrients. Has villi and microvilli which absorb nutrients, which pass into blood and lymph. 3 secti
Large intestine
Portion of intestine that completes the absorption process. Absorbs water and minerals. Contains bacteria that aids in absorption. Also called colon, and gets only undigested food (mostly fiber)
Accessory organs of digestive system
salivary glands, liver, gallbladder, pancreas
salivary glands
secretes saliva, which begins the breakdown of food (carbs)
liver
produces bile and bile is reabsorbed
bile
an emulsifier made by the liver, stored in the gallbladder, and released in the small intestine when needed. Breaks down fat.
Gallbladder
Stores bile. Also has cholecystokinin (CCK) which is a hormone that tells the gallbladder to release bile.
Pancreas
Manufactures bicarbonate, which neutralizes stomach acid in the small intestine. Manufactures enzymes to digest carbs and proteins. Has secretin, a hormone that stimulates bicarbonate release.
Muscles of digestive system
Cardiac sphincter, pyloric valve, ileocecal valve, anal sphincter
cardiac sphincter
Also called lower esophageal sphincter (LES). Prevents contents of stomach from traveling back up esophagus.
pyloric valve (sphincter)
circular muscle of lower stomach that regulates the flow of partly digested food into the small intestine. Sphincter separating the stomach and small intestine
Ileocecal valve
sphincter separating the small and large intestine
anus
sphincter that holds the rectum closed and opens to allow for elimination
sphincter muscles
circular muscle that surrounds and opening and controls when and where food goes
mechanical digestion
Physical breakdown of food by chewing, peristalsis, churning, and mixing. Travels through digestive tract: mouth, esophagus, stomach, small intestine, large intestine
chemical digestion
Chemical breakdown of food by enzymes other secretions. Travels through digestive tract: mouth, esophagus, stomach, small intestine, large intestine
villi
Fingerlike projections of the sheets of cells lining the intestinal tract. Villi make surface area much greater than it would be otherwise
microvilli
Tiny, hairlike projections on each cell of every villus that greatly expand the surface area available to trap nutrient particles and absorb them into cells
digestive problems
diarrhea, constipation, gas/belching, heartburn
Diarrhea
Frequent, loose stools.
Treatment: bowel rest, drink lots of fluids to prevent dehydration
Constipation
Difficult/painful bowel movements
Prevention: eat high fiber diet, drink lots of water, exercise regularly, go when you have to go
Gas/belching
belching, bloating, flatulence
Prevention: eat slowly, choose bothersome foods in moderation
Heartburn
Burning sensation in chest caused by backflow of stomach acid into esophagus. LES (cardiac sphincter) weakens.
Prevention: eat small meals, sit up while eating, don't lay down for 1 hour after eating, don't exercise for 2 hours after eating
Celiac disease
An autoimmune disease that is caused by sensitivity to proteins (gluten) in wheat, rye, and barley. Eating these foods triggers immune response. Damages villi and microvilli of small intestine, which affects absorption of nutrients (no longer absorb them
Gastric Bypass Surgery
Roux-en-Y is one of the most common and most radical types. A pouch holding 3-6 ounces of food is created from the old stomach. Food bypasses the duodenum, so less digestion and absorption. Results in intake of smaller quantities of food AND absorption of