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DIGESTION
MOUTH

Mechanical Digestion
• Teeth break down food

Chemical Digestion
• Enzymes in the mouth break down food

Ex. Salivary amylase
ESOPHAGUS
Tube that leads from the mouth to the
stomach.
• Peristalsis
contractions of the smooth muscle that lines
the esophagus cause food to move down
EPIGLOTTIS
At the back of your throat is your
windpipe (trachea), which allows air to
come in and out of your body.
 When you swallow a flap called the
epiglottis flops down over the
opening of your windpipe to make
sure the food enters the esophagus
and not the trachea.
STOMACH
STOMACH
A muscular sac
 Has GASTRIC GLANDS that secrete
HCl (Hydrochloric Acid) and pepsin
 Has mucus to protect the lining.
 Main site of protein digestion
 The stomach’s partially digested food
is called CHYME

SMALL INTESTINE
SMALL INTESTINE
***Digestion is completed in the
small intestine.***
 About 22 ft long
 Main site of lipid digestion
 Has intestinal glands that make
enzymes

VILLI

Small intestine is lined with villi that
absorb nutrients and diffuses them
into the blood stream
ACCESSORY ORGANS THAT
HELP THE SMALL INTESTINE

Pancreas
• Secretes “juices” which help digestion

Ex. Amylase, Lipase, Protease
ACCESSORY ORGANS THAT
HELP THE SMALL INTESTINE

Liver
• Makes bile

Bile MECHANICALLY breaks down fats
(emulsifies)
ACCESSORY ORGANS THAT
HELP THE SMALL INTESTINE

Gallbladder
• Stores bile and sends it through the bile
duct into small intestine
LARGE INTESTINE/COLON
LARGE INTESTINE/COLON
About 5 ft long
 Water is absorbed here
 Some vitamins are absorbed here
 Undigested material is egested
(defecation)

DISORDERS

Acid Reflux/Heartburn
• The lower esophageal sphincter is just
before the opening to the stomach
• This sphincter opens to let food pass
into the stomach and closes to keep it
there.
• If your L.E.S. doesn’t work properly, the
stomach acid may come back up into
the esophagus. Ouch!
DISORDERS
Constipation/Diarrhea
• If the large intestine absorbs too much
water from the undigested material =
constipation.
• If the large intestine does not absorb
enough water from the undigested
material = diarrhea.
DISORDERS
Ulcers
• A sore in the lining of the stomach or
upper small intestine
• Develop when the stomach’s protective
layer is broken down
Digestive juices can damage the intestine or
stomach tissues, as well as the esophagus
 Don’t forget, gastric juices contain
hydrochloric acid!

DISORDERS

Appendicitis
• Your appendix is inflamed

May have to be removed
DISORDERS

Gall stones
• Hard particles of cholesterol that can
block the bile duct
REPRESENTATIVE ORGANISMS

Amoeba
• 1. pseudopods

Ingestion by phagocytosis
• 2. vacuole

Storage
• 3. lysosome


Has enzymes to digest
As lysosome breaks down, nutrients are absorbed
into cytoplasm
• 4. egestion

across cell membrane
REPRESENTATIVE ORGANISMS

Paramecium
• 1.oral groove

Cilia “sweep” food to oral groove
• 2.vacuole

storage
• 3. lysosome

Breaks down food and nutrients are
absorbed into cytoplasm
• 4. anal pore

Undigested material is egested
REPRESENTATIVE ORGANISMS

Hydra
• 1. tentacles
Have stinging cells
 Help to “sweep” food into mouth

• 2. mouth/site of egestion

Food comes into and out of same area
• 3. gastric cavity
Digestion
 Cells in lining secrete enzymes

REPRESENTATIVE ORGANISMS

Earthworm
• **tube within a tube digestive tract**

1. mouth
• Uses sucking action to pull food in

2.esophagus
• Pulls food into crop

3. crop
• Storage chamber

4. gizzard
• Thick walled muscle that MECHANICALLY crushes food

5.intestine
• Enzymes break down food
• Absorption

6. anus
REPRESENTATIVE ORGANISMS

Grasshopper
• 1. mouth

Mechanical and chemical digestion
• 2. crop

Temporary storage
• 3. gastric area/gizzard

Thick muscular walls of teeth-like plates (chitin) that break
food into smaller pieces
• 4. stomach

Chemical digestion by enzymes
• 5. intestine

Connects stomach to anus
• 6. anus

Has rectum for storage and re-absorption of water