DIGESTIVE SYSTEM & ENZYME NOTES
DIGESTIVE SYSTEM
• Includes mouth, pharynx, esophagus, stomach, small intestine and
large intestine; several major glands and their secretions, including
the salivary glands, the pancreas and the liver
• Digestion is the breakdown of food into simpler molecules that can be
absorbed and used by the cells of the body
DIGESTIVE SYSTEM
• THE PROCESS OF DIGESTION:
• 1. Mouth - teeth break up food in a process called
mechanical digestion; also salivary glands secrete the
first digestive enzymes (amylase and mucous)
• 2. Pharynx - the top part of the throat; no digestion
takes place here
• 3. Esophagus - the muscles of the esophagus begin to
contract in waves, pushing food toward the stomach;
this is called peristalsis
DIGESTIVE SYSTEM
• 4. Stomach - three secretions combine to form the
gastric fluid:
• Mucous - keeps food lubricated and protects
walls of the stomach
• Hydrochloric acid - helps break down food
• Pepsin - mixes with hydrochloric acid to begin
digesting proteins
• The food is churned for several hours becoming a pasty
mixture known as chime
DIGESTIVE SYSTEM
• 5. Small Intestine - the chime is flooded with enzymes
from three sources:
• Duodenum (1st part of small intestine) - releases
enzymes that continue digesting
• Pancreas - releases pancreatic fluid that digests
carbohydrates, proteins and fats
• Liver - secretes bile, which is stored in the gallbladder,
which breaks down fats further
DIGESTIVE SYSTEM
• 5. Small Intestine - the now mostly digested food
passes through the rest of the small intestine where
nutrients are absorbed into the bloodstream; when it
leaves the s.i., the food is nutrient free
• 6. Large Intestine (Colon) - main job is to remove
water from undigested materials passing through it
• 7. Rectum – store feces (solid waste)
Salivary
Glands
Pharynx
Mouth
Tongue
Esophagus
Liver
Liver
Stomach
Pancreas
Stomach
Large Intestine
Small Intestine
Gallbladder
Pancreas
Anus
Appendix
Rectum