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45 Cards in this Set

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Functions of Digestive System
1. Process Food
2. Extract Nutrients from it
3. Eliminates residue
4. Ingestion
5. Digestion
6. Absorption
What does the digestive system produce?
Enzymes and hormones
Order of passage of food
1. Mouth
2. Oral cavity
3. Pharynx
4. Esophagus
5. Stomach
6. Small intestine
7. Large intestine
8. Anal canal
What are the accessory organs?
1. Teeth
2. Salivary glands
3. Liver
4. Gall bladder
5. Pancreas
Layers of the digestive tract
Inside-Outiside
Mucosa
Submucosa
Muscularis externa
Serosa
Mucosa
Inside layer
1. Epithelial cells- villi
2. Lamina propria- loose connective tissue layer
3. Muscularis mucosa- thin layer of smooth muscle
Submucosa
Loose connective tissue
Contains blood vessels, nerves and lymphatic vessels
Glands that secrete mucous
Muscularis externa
Inner layer has circular muscles
Stomach has middle layer- oblique
Outer layer- longitudinal muscles
Function: move food thru the intestine; has pacemaker cells that set the rhythm of contractions.
Serosa adventitia
membrane that lines a body cavity
dense fibrous connective tissue with widely spaced fibers
Digestive tract
Oral cavity
Pharynx
Esophagus
Stomach
Small intestine
Large Intestine
Rectum
Anus
Oral cavity
Mastication- breakdown food
Tongue- skeletal muscle
Teeth- breakdown of food
Salivary glands- moisten food
Intrinsic Salivary glands
Indefinite number
scattered throughout oral tissue
Moisten mouth and inhibit bacterial growth
Extrinsic salivary glands
communicate with oral cavity via ducts, large discrete organs outside of oral cavity
Parotid gland
near earlobe (mumps is an inflammation and swelling of this gland, due to a virus)
Submandibular gland
Halfway along the body of the mandible
Sublingual gland
Floor of mouth
Pharynx
Deglutition- swallowing
Pharyngeal constrictors- force food downward during swallowing
Esophagus
Connects pharynx to stomach
Begins at Cricoid cartilage
Lower esophogeal sphincter keeps food moving in correct direction
Prevents backflow into esophagus
Secrete mucus for lubrication
When empty, has deep ridges which allow for expansion
Heartburn
when stomach acids enter esophagus
Stomach
Breaks food, liquifies food and begins chemmical digestion of proteins and some fat
Rugae
large folds of stomach mucosa
Epithelium cells
Parietal cells: secrete HCL and intrinsic factor
Chief cells: most numerous, secrete pepsinogin
Pepsinogen
an inactive protein that is activated by the HCL of the stomach
Pepsin
(active form) digests dietary proteins to smaller peptide chains
Goblet cells
secrete mucous
Regenerative (stem) cells
divide rapidly for continuous supply of new cells to replace cells that die
Mucous cells
secrete mucous
Enteroendicrine cells
secrete hormones and panacrine messengers taht regulate digestion, eight kinds each producing its own messenger
Chyme
bolus of food material that moves to small intestine
Regions of Stomach
Cardiac orifice
Cardiac region
Fundus region
Body region
Pyloric region
Cardiac orifice
opening from esophagus
Cardiac region
area immediately inside the cardiac orific
Fundus region
Left of the cardiac, in direction contact with diaphragm, dome shaped portion
Body region
main portion forming greater and lesser curvatures
Pyloric region
funnel shaped terminal portion
pylorus opening to small intestine "guarded" by pyloric sphincter
Small intestine function
Chemical digestion and nutrient absorption from chyme
Small intestine parts
1.duodenum- first 10 in., ends at duodenojejunal flexure (sharp curve) receives stomach contents, bile and pancreatic juice
2. Jejunum- next 8 ft, upper left of intestinal coils
3. Ileum- last 12 feet. lower right of intestinal coils
Modifications to increase surface area
1. Plicae circularis: circular folds; mucosa and submucosa layers only; start in the duodenum and continue thorugh the middle of the ileum; cause chyme to flow in a spiral path
2. Villi: fingerlike projection (.5-1.5 mm) largest in the duodenum; epithelial cells consist of absorptive cells and goblet cells.
3. Microvilli: brushborder- projection of apical and cells
Large Intestine Function
Receives about 500 mL of indigestible food a day and reduces it to 150 mL of feces by absorbing water and salts; eliminates feces by defecation
Iliocecal valve
at junction of small/large intestines; one-way passage
Cecum
sac extending inferiorly from iliocecal junction
Appendix
Fingerlike projection off of cecum; it is densely populated with lymphocytes and is a significant source of immune cells- thought to function as part of immune system
Parts of large intestine
Ascending colon: right side
Transverse colon: passes from right to left; inferior stomach and spleen
Descending colon- left side
Sigmoid colon- S-shaped near rectum
Rectum
straight part of the large intestin; has three valves taht allow for retaining feces but passing gas
Anus
where feces leave body