Ans

1. Name____________________________ Class__________________ Date __________
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
372
The Respiratory System
Air enters the body through the mouth and nose. It passes through
air passages and fills the lungs. In the lungs, oxygen enters the
bloodstream and carbon dioxide leaves the bloodstream.
Use the words below to label the diagram.
bronchus lung pharynx
larynx nose trachea
larynx
trachea
bronchus
lung
pharynx
nose
Use the diagram to answer the question. Circle the correct answer.
1. Which structure does air enter after the nose?
bronchus pharynx

2. Name____________________________ Class__________________ Date __________
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
373
Gas Exchange
In the lungs, gas exchange takes place in millions of tiny air
sacs called alveoli. Oxygen diffuses from the alveoli through
the capillary walls into the blood. Carbon dioxide diffuses in the
opposite direction.
Follow the prompts to identify important parts of the diagram.
• Color the areas containing oxygen-poor blood blue.
• Color the areas containing oxygen-rich blood red.
• Color the areas in which gas exchange takes place purple.
vein
alveoli
bronchiole
(blue)
artery
capillary wall
red blood cell
O2
CO2
(purple)
(purple)
(red)
Use the diagram to answer the question. Circle the correct answer.
1. What diffuses from red blood cells into the alveoli?
carbon dioxide oxygen