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Flashcards in Gastrointestinal System (Functions) Deck (41)
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Digestion

breaking down of larger food particles into molecules small enough to enter the body cells

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ingestion

taking foods and liquids into the mouth

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secretion

water, acid, buffers and enzymes secreted into the lumen

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lumen

interior space

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mixing and propulsion

alternating contractions and relaxations of smooth muscle mixes food

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mechanical digestion

chewing/grinding food (mastication)
churning of food in the stomach and small intestine
consists of various movements that aid in chemical digestion; food must be pulverized by teeth

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chemical digestion

enzymes break down food into smaller molecules
series of catbolic reactions that break down the large carbohydrate, lipd, and protein molecules that we eat, into smaller molecules usable by body cells

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absorption

entrance of ingesed materials into epithelial cells that line the lumen of the GI tract

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defecation

waste leaves the body; feces

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teeth

cut, tear, and pulverize food
reduce to smaller particles for swallowing

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extrinsic muscle (tongue)

move tongue from side to side and in and out
food (bolus) maneuvered for mastication and swallowing

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intrinsic muscle (tongue)

alter shape of the tongue
swallowing and speech

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taste buds

receptors for food stimulus

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glands

secrete lingual lipase
breaks down triglycerides into fatty acids

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major salivary glands (parotid, submandiable, sublingual

secrete saliva in the lining of the mouth and pharynx
softens moistens and dissolves food
cleanses mouth and teeth
saliva amylase splits polysaccharides into smaller particles

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pharynx

pharngeal stage of swallowing (deglutition)
moves bolus from oropharynx to laryngopharynx and into the esophagus
closes air passage ways

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esophagus

esophageal stage of swallowing: forces bolus down the esophagus
relaxation of upper and lower esophageal sphincter: permits entry of bolus from laryngopharynx into esophagus and eventually into the stomach
secretion of mucus lubricates esophagus for smooth passage of bolus

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stomach

the primary digestive organ

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mucosa

chief cells: secretes pepsinongen (breaks peptide bonds in protein
secretes gastric lipase (splits short chain triglycerides into fatty acids and monoglycerides

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parietal cells

secretes hydrochloric acid (kills microbes in food, modifies the molecular structure of protein, inhibits secretion of gastrin)
secretes intrinsic factor (needed for absorption of vitamin B12

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muscosa surface cells

secretes mucous (forms a protective barrier that prevents digestion of the stomach wall)

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enteroendocrine cells

secretes gastrine (stimulates paretal cells to secrete HCL and chief cells to secrete pepsinogen, contracts lower esphageal sphincter, increase motility of the stomach, relaxes pyloric sphincter)

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muscularis

mixing waves (masecerate food and mix with gastric juices to form chyme)
peristalisis (froces chyme through pyloric sphincter)

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pyloric sphincter

opens to permit passage of chyme to duodenum

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pancreas

secondary organ aiding chemical digestion in the small intestine

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pancreatic juice

buffers acidic gastric juices into chyme
stops the action of pepsin from the stomach
creates the proper pH balance for action of digestive enzymes in the small intestine

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liver

heaviest gland in the body
second organ aiding in chemical digestion

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liver (functions)

carbohydrate metabolism - maintains normal blood glucose level
lipid metabolism
protein metabolism
removal of drugs and hormones
exretion of bilirubin
strorage of some vitamins and minerals
avtivation of vitamin D

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gallbladder

secondary organ aiding chemical digestion
store and concentrate bile

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small intestine

major site of digestion and absorption