1. Warm-Up • Define words for 33.3

2. Ch. 33.3 – The Respiratory System

3. Background Information • All cells require a constant supply of oxygen for cellular respiration. • Recall C6H12O6 + 6O2 --> 6H2O + 6CO2 + ATP • Respiration means the process of gas exchange between a body and the environment. • Human respiratory system picks up oxygen from the air we inhale and releases carbon dioxide into the air we exhale. • With each breath air fills our lungs and gas exchange occurs there. • The circulatory system links the gas exchange to the rest of our body.

4. Structures of the Respiratory System

5. Consists of • The nose • The pharynx • The trachea • The bronchi • The lungs

6. The Nose • Air must be filtered, moistened and warmed before entering the lungs • Hairs lining the entrance to the nasal cavity trap large particles • Incoming air is warmed in the inner nasal cavity and sinuses. • Mucus is produced that moistens the air and further filters.

7. The Pharynx • A cavity at the back of the mouth • Also called the throat • Serves as a passageway for both air and food

8. The Larynx • After the pharynx air moves through the larynx to the trachea. • Contains two highly elastic folds of tissue known as the vocal cords. • These tissues give you the ability to produce sounds • When muscles pull the vocal cords together, the air moving between them causes the cords to vibrate and produce sounds.

9. The Trachea • Also known as the windpipe • When you shallow food or liquids, the epiglottis (a flap of tissue) covers the entrance to make the food or liquids go down the esophagus. • Lined with mucus that trap any inhaled particles. • Cilia lining the trachea sweep both the mucus and trapped particles upwards towards the pharynx. • From there, the mucus and particles can be swallowed or spit out • This helps keep the lungs clean and open form the important work of gas exchange.

10. The Lungs • Air then moves into the bronchi (singular: bronchus) – which are two large tubes in the chest cavity leading to each of the lungs. • The bronchus divides into smaller bronchi which then divides into the bronchioles (even smaller) • Bronchi and bronchioles are surrounded by smooth muscle tissue controlled by the autonomic nervous system • As the muscles contract and relax, the size of the passageways change. • Further divide until they reach the alveoli (singular: alveolus) • Alveoli are grouped into clusters • Surrounded by a delicate network of capillaries where the gas exchange occurs.