The Respiratory System

1. The Respiratory System

2. Function of the Respiratory System • To bring about the exchange of oxygen and carbon dioxide between the blood, the air, and tissues.

3. The Respiratory System Includes: • Nose • Pharynx • Larynx • Trachea • Bronchi • Lungs

4. 2. Pharynx • Air moves through the nose to a tube at the back of the mouth called the pharynx, or throat. • Pharynx - Serves as a passageway for both air and food.

5. 3. Larynx • Located at the top of the trachea. • Contains two highly elastic folds of tissue known as the vocal cords. • When muscles pull the vocal cords together, the air moving between them causes the cords to vibrate and produce sounds. • Your ability to speak, shout, and sing comes from these tissues.

6. 4. Trachea • Air moves from the pharynx into the trachea, or windpipe. • A flap of tissue called the epiglottis covers the entrance to the trachea when you swallow

7. The Respiratory Passageway • To keep lung tissue healthy, air entering the respiratory system must be: • Warmed • Moistened • Filtered • Hairs trap large dust particles. • Cells produce a thin layer of mucus, which moistens the air and traps inhaled particles of dust or smoke. • Cilia sweep the trapped particles and mucus away from the lungs toward the pharynx. Then the particles are either swallowed or spit out. • Helps keep lungs clean and open for gas exchange. Cilia in the respiratory tract.

8. 5. Bronchi • From the larynx, air passes through the trachea into two large passageways in the chest cavity called bronchi. • Each bronchus leads into one of the lungs. • The large bronchus subdivides into smaller bronchi, which lead to even smaller passageways called bronchioles. • Surrounded by smooth muscle enables the nervous system to regulate the size of the air passageways.

9. Alveoli • The bronchioles continue to subdivide until they reach a series of dead ends—millions of tiny air sacs called alveoli. • Grouped in little clusters, like bunches of grapes. • A delicate network of thin-walled capillaries surrounds each alveolus. • This is where gas exchange occurs because blood and air are side by side.

10. Gas Exchange • Each healthy lung contains about 150 million alveoli ! • Provides for an enormous surface area for gas exchange. • Oxygen • Dissolves in the moisture on the inner surface of the alveoli and then diffuses across the thin-walled capillaries into the blood. • Carbon Dioxide in the Bloodstream • Diffuses in the opposite direction, across the membrane of an alveolus and into the air within it.

11. Breathing • Breathing is the movement of air into and out of the lungs. • The force that drives air into the lungs comes from ordinary air pressure. • Diaphragm – Large, flat muscle at the bottom of the chest cavity that helps with breathing.

12. Breathing • Inhaling (Breathing in) • Diaphragm contracts (pushes down) and the rib cage rises up. • Exhaling (Breathing out) • Passive event • Diaphragm relaxes and the rib cage lowers.

13. How Breathing Is Controlled • You have some voluntary control over breathing. • The medulla oblongata in the brain also monitors carbon dioxide levels in the blood. • It forces you to breathe even if you are trying to hold your breathe. • As the CO2 levels rise, nerve impulses from the brain cause the diaphragm to contract, bringing air into the lungs.

14. Tobacco and the Respiratory System • The upper respiratory tract can usually filter out dust and foreign particles that could damage the lungs. • Tobacco smoke contains nicotine, carbon monoxide, and tar. • Smoking can cause chronic bronchitis, emphysema, and lung cancer.