Respiratory and Circulatory Systems
Detailed Lesson • Reviewer • Activities
Introduction
The respiratory and circulatory systems work together to transport oxygen, nutrients, and wastes throughout the
body. The respiratory system allows breathing, while the circulatory system distributes blood and oxygen to the
body.
What is the Respiratory System
What is the main function of your
respiratory system? respiratory system?
The main function of your
Your respiratory system is the
respiratory system is to
organs and structures in your
pull in oxygen for your
body that allow you to breathe. It
body’s cells and get rid of
includes your lungs, nose,
carbon dioxide, a waste
mouth and the tubelike
product. You do this by
structures (airways) that connect
breathing in and out and
them. You also have muscles
through gas exchange
and blood vessels that support
between the small air
your respiratory system, and
sacs of your lungs
ribs to protect it. These parts
(alveoli) and the blood
work together to bring oxygen
vessels running nearby.
into your body when you inhale
and get rid of carbon dioxide
when you exhale.
The system is divided into two main parts: the upper respiratory tract (airways outside the chest cavity)
and the lower respiratory tract (airways inside the lungs).
Nose and Mouth: Entryways where air is warmed, moistened, and filtered.
Pharynx and Larynx: The throat and voice box. A flap of tissue called the epiglottis covers the larynx
when swallowing to prevent food from entering the windpipe.
Trachea (Windpipe): The main airway that branches into the chest.
Bronchi & Bronchioles: Tubes that branch off the trachea and lead deeper into the lungs, getting
progressively smaller.
Alveoli: Tiny air sacs at the end of the bronchioles where gas exchange happens. Oxygen moves into the
blood, and carbon dioxide is pushed out.
Diaphragm: The main muscle responsible for breathing; its contraction and relaxation pull air into and
push air out of the lungs.
Detailed Lesson • Reviewer • Activities
Introduction
The respiratory and circulatory systems work together to transport oxygen, nutrients, and wastes throughout the
body. The respiratory system allows breathing, while the circulatory system distributes blood and oxygen to the
body.
What is the Respiratory System
What is the main function of your
respiratory system? respiratory system?
The main function of your
Your respiratory system is the
respiratory system is to
organs and structures in your
pull in oxygen for your
body that allow you to breathe. It
body’s cells and get rid of
includes your lungs, nose,
carbon dioxide, a waste
mouth and the tubelike
product. You do this by
structures (airways) that connect
breathing in and out and
them. You also have muscles
through gas exchange
and blood vessels that support
between the small air
your respiratory system, and
sacs of your lungs
ribs to protect it. These parts
(alveoli) and the blood
work together to bring oxygen
vessels running nearby.
into your body when you inhale
and get rid of carbon dioxide
when you exhale.
The system is divided into two main parts: the upper respiratory tract (airways outside the chest cavity)
and the lower respiratory tract (airways inside the lungs).
Nose and Mouth: Entryways where air is warmed, moistened, and filtered.
Pharynx and Larynx: The throat and voice box. A flap of tissue called the epiglottis covers the larynx
when swallowing to prevent food from entering the windpipe.
Trachea (Windpipe): The main airway that branches into the chest.
Bronchi & Bronchioles: Tubes that branch off the trachea and lead deeper into the lungs, getting
progressively smaller.
Alveoli: Tiny air sacs at the end of the bronchioles where gas exchange happens. Oxygen moves into the
blood, and carbon dioxide is pushed out.
Diaphragm: The main muscle responsible for breathing; its contraction and relaxation pull air into and
push air out of the lungs.
