Explain the process of digestion along the alimentary canal including:
1. Chemical or mechanical digestion
a. Mechanical digestion: begins in the mouth as the food is chewed, where we
physically breaking the food into smaller pieces in the mouth. After swallowing
the food (churn) it moves to the stomach and segmentation in the small
intestine.
b. Chemical digestion: involves breaking down the food into simpler nutrients that
can be used by the cells in our bodies.
2. Structural adaptations and the link to their functions
a. Mouth
b. Esophagus
c. Stomach
d. Small intestine
e. Pancreas
f. Liver
g. Gallbladder
h. Colon (large intestine)
i. Rectum
j. Anus
 For more details on their functions check the notes I’ve given you or this website.
https://my.clevelandclinic.org/health/articles/7041-the-structure-and-function-ofthe-digestive-system
3. Chemicals/substances produced and their function in the process of digestion
 Mouth  moves food to the pharynx
o Begins breakdown of lipids
o Begins the chemical breakdown of carbohydrates
o Chews and mixes food
o Ingests food

Esophagus  propels food to the stomach
o Mixes churns food with gastric juices to form chyme
o Begins chemical breakdown of proteins

Stomach: releases food into the duodenum as chyme
o Absorbs some fat-soluble substances (for example, alcohol, aspirin).
o Possesses antimicrobial functions

Small intestine  mixes chyme with digestive juices
o Propels food at a rate slow enough for digestion and absorption.
o Absorbs breakdown products of carbohydrates, proteins, lipids, nucleic acids,
along with vitamins, minerals, and water.
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Liver:  produces bile salts, which emulsify lipids, aiding their digestion and
absorption.
Gallbladder: stores, concentrates, and releases bile.
Pancreas: produces digestive enzymes and bicarbonate
Large intestine  further breaks down food residues
o Absorbs most residual water, electrolytes, and vitamins produced by enteric
bacteria.
o Propels feces towards the rectum
o Eliminates feces.
4. Where along the canal different nutrients are digested?
a. Breakdown of food occurs in the small intestine where enzymes are produced by
the liver, the small intestine, and the pancreas continue the process of digestion.
b. The nutrients are absorbed into the bloodstream across the epithelial cells lining
the walls of the small intestine.
c. The small intestine is where most of the nutrients are absorbed and it also
absorbs water.
Quiz: Digestive System
Which of these processes occurs in the mouth?
a. ingestion
b. mechanical digestion
c. chemical digestion
d. all of the above
D
Which of these processes occurs throughout most of the alimentary canal?
a. ingestion
b. propulsion
c. segmentation
d. absorption
B
Which of the following stimuli activates sensors in the walls of digestive organs?
a. breakdown products of digestion
b. distension
c. pH of chyme
d. all of the above
D
Glossary
absorption
passage of digested products from the intestinal lumen through mucosal cells and into
the bloodstream or lacteals
chemical digestion
enzymatic breakdown of food
chyme
soupy liquid created when food is mixed with digestive juices
defecation
elimination of undigested substances from the body in the form of feces
ingestion
taking food into the GI tract through the mouth
mastication
chewing
mechanical digestion
chewing, mixing, and segmentation that prepares food for chemical digestion
peristalsis
muscular contractions and relaxations that propel food through the GI tract
propulsion
voluntary process of swallowing and the involuntary process of peristalsis that moves
food through the digestive tract
segmentation
alternating contractions and relaxations of non-adjacent segments of the intestine that
move food forward and backward, breaking it apart and mixing it with digestive
juices