Chapter 13 – Part 2 The Respiratory System

1. Chapter 13 – Part 2The Respiratory System

2. Trachea (Windpipe) • Connects larynx with bronchi • About 4 inches long • Lined with ciliated mucosa • Beat continuously in the opposite direction of incoming air • Propels mucus loaded with dust and other debris away from lungs to the throat, where it can be swallowed or spat out

3. The Trachea and Smoking • Smoking inhibits ciliary activity and ultimately destroys the cilia • Without these cilia, coughing is the only means of preventing mucus from accumulating in the lungs

4. Trachea (Windpipe) • The trachea is fairly rigid because its walls are reinforced with C-shaped hyaline cartilage • These rings form two purposes: • Support the trachea and keep it open in spite of the pressure changes that occur during breathing • Allows it to expand anteriorly when we swallow a large piece of food

5. Heimlich Maneuver • Heimlich Maneuver – A procedure in which the air in a person’s own lungs is used to “pop out,” or expel, an obstructing piece of food • Because the trachea is the only way air can get into the lungs, tracheal obstruction is life-threatening • Many people have suffocated after choking on a piece of food that suddenly closed off the trachea • Has saved many people from choking to death

6. Primary Bronchi • The right and left primary bronchi is formed by the division of the trachea • Enters the lung at the hilus (medial depression) • Right Bronchus - Wider, shorter, and straighter than left bronchus • Consequently it is the more common site for an inhaled foreign object to become lodged • Bronchi subdivide into smaller and smaller branches • By the time air enters the bronchi, it is warmed, cleansed of most impurities, and well humidified

8. Lungs • The paired lungs are fairly large organs • Occupy most of the thoracic cavity • Apex is near the clavicle (narrow, superior portion) • The broad base rests on the diaphragm (inferior portion) • The bronchi enters the lung at the hilus (medial depression)

10. Lungs • Each lung is divided into lobes by fissures • Left Lung - Has two lobes • Right Lung - Has three lobes

11. Coverings of the Lungs • Pulmonary (Visceral) Pleura - Covers the lung surface • Parietal Pleura - Lines the walls of the thoracic cavity • Pleural Fluid - Fills the area between layers of pleura to allow gliding during breathing movements • Can slide easily from side to side across one another, but resists being pulled apart.

12. Lungs

13. Coverings of the Lungs • Pleurisy – Inflammation of the pleura • Can be caused by the decreased secretion of pleural fluid • The pleural surfaces become dry and rough • Results in friction and stabbing pain with each breath

14. Respiratory Tree Divisions • This branching and rebranching within the lungs is often referred to as the bronchial or respiratory tree: • Primary bronchi • Secondary bronchi • Tertiary bronchi • Bronchioles • Terminal bronchioles

15. Bronchioles • Bronchioles - Smallest branches of the bronchi • All but the smallest branches have reinforcing cartilage

16. Bronchioles • Terminal bronchioles end in alveoli, or air sacs.

17. Respiratory Zone • The respiratory zone is the only site of gas exchange • Includes the following structures: • Respiratory bronchioles • Alveolar ducts • Alveolar sacs • Alveoli • All other respiratory passages are conducting zone structures, which serve as conduits to and from the respiratory zone.

18. Alveoli • There are millions of the clustered alveoli, which resemble bunches of grapes. • They make up the bulk of the lungs • Consequently, the lungs are mostly air space • In spite of their relatively large size, the lungs weigh only about 2 ½ pounds, and they are soft and spongy

19. Alveoli • Structure of alveoli • Alveolar duct • Alveolar sac • Alveoli • Gas exchange takes place within the alveoli in the respiratory membrane

20. Respiratory Membrane • Respiratory Membrane (Air-Blood Barrier) – Has gas (air) flowing past on one side and blood flowing past on the other • Made up of the alveolar and capillary walls and their fused basement membranes.

21. Respiratory Membrane • The walls of the alveoli are composed largely of a single, thin layer of squamous epithelial cells • The thinness of their walls is hard to imagine, but a sheet of tissue paper is much thicker • The external surfaces of the alveoli are covered with a “cobweb” of pulmonary capillaries

22. Respiratory Membrane • Alveolar pores connect neighboring air sacs and provide alternate routes for air to reach alveoli • In case feeder bronchioles have been clogged by mucus or otherwise blocked

23. Gas Exchange • Gas exchanges occur by simple diffusion through the respiratory membrane • Oxygen enters the blood • Carbon dioxide enters the alveoli • The total gas exchange surface provided by the alveolar walls is 40 times greater than the surface of your skin

24. Gas Exchange • The final line of defense for the respiratory system is in the alveoli • Macrophages wander in and out of the alveoli picking up bacteria, carbon particles, and other debris • Surfactant coats the gas-exposed alveolar surfaces • Lowers the surface tension of the film of water lining each alveolar sac so that the alveoli do not collapse between each breathe

25. Respiratory Membrane (Air-Blood Barrier)