overview of the digestive system Flashcards
how many groups of organs compose the digestive system? name them.
2 groups of organs: the gastrointestinal tract and the accessory digestive organs
what is the GI tract or alimentary canal?
is a continuous tube that extends from the mouth to the anus
from where to where does the GI tract contain food?
the GI tract contains food from the time it is eaten until it is digested and absorbed or eliminated from the body
name the organs of the GI tract.
the mouth, pharynx, esophagus, stomach, small intestine, and large intestine
what is the length of the GI tract?
about 5-7 meters (16.5-23 ft) in a living person
why is it longer in a cadaver ( about 7-9 meters or 23-29.5 ft)?
because the muscles along the wall of the GI tract organs are in a state of tonus (sustained contraction)
name the accessory digestive organs.
the teeth, tongue, salivary glands, liver, gallbladder, and pancreas
What do the teeth and tongue do?
teeth aid in the physical breakdown of food, and the tongue assists in chewing and swallowing
do the other accessory digestive organs come into direct contact with food?
they never come into direct contact with food
through what do the secretions that they produce or store flow into the GI tract and aid in what?
through ducts and aid in the chemical breakdown of food
how many basic processes does the digestive system perform?
6 basic processes
1) ingestion
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what does this process involve?
taking foods and liquids into the mouth (eating)
2) secretion
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what do cells within the walls of the GI tract and accessory organs secrete and into what?
each day, cells within the walls of the GI tract and accessory organs secrete a total of about 7 liters of water, acid, buffers, and enzymes into the lumen of the tract
3) mixing and propulsion
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what mixes food food and secretions and propel them toward the anus?
alternating contractions and relaxation of smooth muscle in the walls of the GI tract
what is the ability of the GI tract to mix and move material along its length termed as?
motility
4) digestion
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what do mechanical and chemical processes do to ingested food?
they break down ingested food into small molecules
what happens in mechanical digestion (teeth, smooth muscles of the stomach and small intestine)?
the teeth cut and grind food before it is swallowed, and then smooth muscles of the stomach and small intestine churn the food
what is its result?
as a result, food molecules become dissolved and thoroughly mixed with digestive enzymes
what happens in chemical digestion?
the large carbohydrate, lipid, protein, and nucleic acid molecules in food are broken down into smaller molecules by digestive enzymes
5) absorption
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