1. Respiratory System
Take a deep breath and relax Respiration: The exchange of oxygen from environment for carbon dioxide from the body’s cells.

2. Structure Pharynx Nose Larynx Trachea Mouth Lungs Epiglottis Bronchi
Diaphragm
Bronchioles
Alveoli

3. Nose- lined with mucous membranes. Air is warmed, filter and moistened
Pharynx or throat- Carries food and air. Esophagus branches off here
Larynx or voice box- Short tube contains vocal cords. Uppermost part of air only passage.
Trachea or windpipe-extends from base of larynx to lungs. Lined with cilia.
Epiglottis- tiny flap that covers opening to trachea during swallowing keeping food and liquid from going into our lungs.

4. Bronchi - left and right air tubes that extend into the lungs.
Bronchioles- smaller branches of the bronchi which are as thin as a strand of hair.

5. Bronchioles end in small air sacs called alveoli
Bronchioles end in small air sacs called alveoli. We have 100’s of millions of alveoli in our lungs.
Alveoli are surrounded by capillaries that are filled with blood.

6. Gas exchange takes place in the alveoli.
What gases are exchanged? Diffusion: Oxygen moves from alveoli to the blood through the capillaries. Blood flows to the heart, through arteries to tissues. Carbon dioxide produced during diffusion returns to heart through the veins and back to lungs where it’s passed to Alveoli to be exhaled.

7. Muscles used in breathing – Diaphragm, intercostal muscles, throat and neck muscles.
When we breathe in Diaphragm moves?
When we breathe out Diaphragm moves?