Transcript Digestion - District 128 Moodle

Digestion
Life Science
Digestive System

Organs that break down food so it can be
used by the body.
 Digesting food takes about 24 hours.
 2 types of digestion
– Mechanical digestion
• Breaking, crushing, mashing food
• Teeth, muscles
– Chemical Digestion
• Large molecules broken down into nutrients
• Enzymes, acid, bile
Where does my food go?

1. Mouth
– Teeth
• Break food apart
• Grind, shred food
– Saliva
• Makes food easier to swallow
• An enzyme (amylase) starts to digest
carbohydrates
Next stop…

2. Esophagus
– Squeezes food down
– Muscular, peristalsis (muscular waves)
– Connects pharynx (throat) to stomach
Next stop…

3. Stomach
– Squeezes food with muscular contractions
– Enzymes produced
• Break down food into nutrients
– Acid produced
• Break down food into nutrients
• Kill possibly harmful bacteria
– Makes liquid chyme
Next stop…
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4. Small Intestine
– Chyme is slowly released from the stomach to the
small intestine
– Proteins, carbohydrates, and fats in chyme are
digested in the small intestine.
– Thin, very long (6 meters)
– Have villi – projections which stand out and
absorb nutrients.
– If flattened, the surface would be larger than a
tennis court!
Pause…

Pancreas
– Secretes fluid into small intestine
• Digests chyme (enzymes)
• Neutralizes chyme (was acidic in stomach)
• Makes insulin which regulates blood sugar
Pause…
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Liver
– Cool things:
• Largest organ in the body (football)
• Stores and filters blood
– Cool things about digestion:
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Makes bile (breaks up fat)
Stores nutrients for later use
Releases nutrients as they are needed
Breaks down toxins
Pause…

Gallbladder
– Stores bile
– Releases bile into the small intestine
– Bile breaks large fat droplets into small fat
droplets
– This allows fat molecules to be exposed to
many digestive enzymes (fat molecules will
get as small as possible)
Next stop…
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5. Large Intestine
– All undigested material ends up here
– Water is absorbed into the blood
– Undigested material is stored, compacted.
– The product is called feces or stool.
– Fiber (cellulose) from whole grains, fruits
and vegetables keep stool softer.
All aboard!

6. Rectum
– Last part of the large intestine.
– Stores feces until it is released.

7. Anus
– The opening of the body where feces exits.