1. Respiratory System

2. Two types of respiration
Cellular respiration – the release of energy from the breakdown of food molecules making ATP.
External respiration- the process of exchanging oxygen from the atmosphere and carbon dioxide from the body.

3. Parts of the respiratory system
Nose
Pharynx- tube that connects the nose and mouth to the trachea and esophagus.
Epiglottis- a flap of tissue that covers the trachea when eating to prevent food from entering the lungs.

4. Parts of the respiratory system
Trachea- a cartilage reinforced tube that brings air into the lungs.
Larynx- two elastic folds of tissue at the top of the trachea that allow humans to make noise
Bronchi – two large tubes that connect the trachea to the lungs.

5. Parts of the respiratory system
Bronchioles- smaller airways that branch off the bronchi.
Alveoli- tiny air sacs where oxygen and carbon dioxide are exchanged in the blood.

6. Protecting the lungs
Cilia – tiny hairs that trap particles and move mucus out of lungs.
Mucus – thick liquid that traps smaller particles
Surfactant – liquid that coats the walls of the alveoli to increase flexibility

7. Mechanics of Breathing
The chest cavity is a sealed compartment with a large, flat muscle called the diaphragm across the bottom.

8. Mechanics of Breathing
Inhalation
The diaphragm contracts and the lung volume expands.
This causes the pressure inside the lungs to drop below the pressure of the air outside.
Air rushes into the lungs.

9. Mechanics of Breathing
Exhalation
When the chest and diaphragm muscles relax, the volume in the lungs decreases
The pressure in the chest increases.
The air is pushed out of the lungs

10. Controlling breathing
The levels of carbon dioxide in your blood tells your body when to breathe.
High levels = fast breathing
Low levels = slow breathing
Your body will override attempts to hold breath too long.