196
UNIT 5: Structure and Function of Organisms, Part 2
Lesson 1: Physical and Chemical Changes in Digestion
DID YOU KNOW?
Hydrochloric acid
breaks down food and also kills bacteria and viruses that are
ingested with the food.
The chyme moves into the small intestine, and different digestive enzymes from the
liver and pancreas continue breaking the molecules down. Approximately 6–8 hours
after the food enters the mouth, it has been physically and chemically broken down
into simple molecules that are easily absorbed into the blood through the small
intestine’s villi. The circulatory system then transports the digested food to the cells
of the body.
Villi increase the surface area in the intestines for nutrient absorption.
Dangerous metabolic by-products such as hydrogen peroxide are chemically
changed into less harmful substances by enzymes. Indigestible parts of chyme are
moved along to the large intestine, where usable water and minerals are absorbed.
Unusable waste material is expelled from the anus.S
cienc
e
9 3/4 x 7 1/2 in. • 24.7 x 19.0 cm Create a table similar to the one below that
describes whether physical
changes, chemical changes, or both physical and chemical changes occur in
each
organ.
Organ
Physical, Chemical, or Physical and
Chemical Changes
mouth
esophagus
stomach
small intestine
large intestine
UNIT 5: Structure and Function of Organisms, Part 2
Lesson 1: Physical and Chemical Changes in Digestion
DID YOU KNOW?
Hydrochloric acid
breaks down food and also kills bacteria and viruses that are
ingested with the food.
The chyme moves into the small intestine, and different digestive enzymes from the
liver and pancreas continue breaking the molecules down. Approximately 6–8 hours
after the food enters the mouth, it has been physically and chemically broken down
into simple molecules that are easily absorbed into the blood through the small
intestine’s villi. The circulatory system then transports the digested food to the cells
of the body.
Villi increase the surface area in the intestines for nutrient absorption.
Dangerous metabolic by-products such as hydrogen peroxide are chemically
changed into less harmful substances by enzymes. Indigestible parts of chyme are
moved along to the large intestine, where usable water and minerals are absorbed.
Unusable waste material is expelled from the anus.
cienc
e
9 3/4 x 7 1/2 in. • 24.7 x 19.0 cm
describes whether physical
changes, chemical changes, or both physical and chemical changes occur in
each
organ.
Organ
Physical, Chemical, or Physical and
Chemical Changes
mouth
esophagus
stomach
small intestine
large intestine
