digestive system
Post on 02-Nov-2014
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The Digestive System
A Study GuideMs. Bennett’s Living Environment
The purpose of the Digestive System
To make big things into small things
The Parts of the Digestive System
The Mouth
Teeth grind food into swallowable substance (bolus)
Mechanical and chemical digestion take place here
Enzymes in saliva start to break down starches.
EsophagusMuscular contractions move the bolus to the stomach
These contractions are called peristalsis
No new digestion occurs
Stomach
Stomach is very muscular and churns the food into a paste (chyme).
Stomach makes acid which helps break down proteins.
Small IntestineNo new mechanical digestion takes place
Enzymes break down proteins, starches, and fats
Nutrients are absorbed into the bloodstream via the villi.
Large Intestine
Undigested food (now called feces) passes into the large intestine.
Water, minerals, and vitamins are reabsorbed.
Anus/Rectum
The rectum stores feces until it is ready to be released.
The anus is the opening through which feces is released.
Types of DigestionPartPart MechanicalMechanical ChemicalChemical
Mouth ChewingEnzymes
from saliva
Esophagus
NoneNone (still continuing
from mouth)
StomachChurning of
FoodAcid from
gastric juiceSmall
IntestineNone Enzymes
Large Intestine
None
Reabsorption of water
and minerals
EnzymesEnzymes are chemicals that speed up chemical reactions.
Enzymes used in digestion help break big things into small things.
3 types of enzymes
Proteases - act on proteins
Amylases - act on starch
Lipases - act on fats
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