Both the respiratory system and the digestive system involve the uptake of
necessary molecules from an animal's surroundings. Alveoli are tiny sacs that aid in
the exchange of carbon dioxide and oxygen in the lungs. Intestinal villi are tiny
projections along the lining of the intestines used to take in nutrients from food
passing through.
Alveoli
Intestinal Villi
M
GAIN
O
CLEAR ALL
Endocrine
Integumentary
Immune
Circulatory