The Human Respiratory System Definition: A group of organs working together to bring about the exchange of oxygen (O2) and carbon dioxide (CO2) with the environment. Bill Nye on Respiration

Anatomy of the Respiratory System Nose Nasal Cavity Pharynx Larynx Trachea Left Bronchus Right Bronchus Left Lung Right Lung Bronchioles and Alveoli Diaphragm

Pharynx: Located at the back of mouth Pharynx: Located at the back of mouth. Serves as a passageway for both air and food. Pharynx

Trachea: Also known as the windpipe. Leads to the lungs Trachea: Also known as the windpipe. Leads to the lungs. Filters dust, dirt, smoke etc. Trachea

Larynx - Cartilage structure at the top of the trachea that contains the vocal cords. The “voice box”or “Adam’s apple”. Vocal Cords - consist of 2 elastic folds of tissue in larynx. As air passes through, they vibrate and produce sound. Larynx and vocal cords

Bronchi: (plural) In the chest cavity, the trachea divides into 2 branches that enter each lung. Left Bronchus Right Bronchus

Lungs: Organs of respiration specialized for the exchange of gases between the blood and the atmosphere Left Lung Right Lung

Alveolus: Air sac at the end of a bronchiole where gas exchange occurs Bronchiole: One of the finest branches of the bronchial tubes; ends in an air sac Alveolus: Air sac at the end of a bronchiole where gas exchange occurs Bronchioles and Alveoli

The Mechanics of Breathing Inhalation The diaphragm is a large, flat muscle located along the bottom of the rib cage. It separates the chest cavity from the abdominal cavity During inhalation, the diaphragm contracts and moves down. As the chest cavity expands in size, the volume increases and the pressure decreases relative to the atmosphere. To equalize the pressure, air rushes into the lungs. Inhalation is also called inspiration.

The Mechanics of Breathing Exhalation During exhalation, the diaphragm relaxes and moves up. As the chest cavity decreases in size, the volume decreases and the pressure increases relative to the atmosphere. To equalize the pressure, air rushes out of the lungs! Exhalation is also called expiration. Watch an animation!