The Respiratory System

1. The Respiratory System Chapter 24

2. Introduction • Cells obtain oxygen and eliminate carbon dioxide • The respiratory system facilitates the exchange of gases between the air and the blood • Blood carries oxygen from the lungs to peripheral tissues • Blood accepts the carbon dioxide produced from peripheral tissues

3. The Respiratory System • Includes the nose, nasal cavity and sinuses, pharynx, larynx, trachea, and conducting passageways to gas-exchange lung surfaces • The respiratory tract consists of the airways that carry air to and from these surfaces: • Conducting portion – entrance to the nasal cavity to the smallest bronchioles • Respiratory portion – includes the respiratory bronchioles and the alveoli (air sacs)

4. Upper respiratory system – nose, nasal cavity, paranasal sinuses, and pharynx - filters, warms, and humidifies the air - protects the conduction and exchange surfaces of the lower respiratory system from debris, pathogens, environmental extremes • Lower respiratory system – larynx, trachea, bronchi, and lungs • filtering, warming, humidifying continues • by the time air reaches lung alveoli most foreign particles and pathogens have been removed • ‘Conditioning process’ – primarily properties of the respiratory epithelium

5. Figure 24.1 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

6. Functions • Providing an extensive area for gas exchange • Moving air to and from lung exchange surfaces • Protecting respiratory surfaces • Defending the respiratory system & other tissues from invasion by pathogenic microorganisms • Producing sounds involved in speaking, singing, or nonverbal communication • Assisting in the regulation of blood volume, blood pressure, and the control of body fluid pH

7. The Respiratory Epithelium • Pseudostratified, ciliated, columnar epithelium – numerous mucous cells - lines the entire respiratory tract except for inferior portions of the pharynx (stratified squamous epithelium: abrasion & chemical insults), and the smallest conducting passages and the alveoli - sticky mucus bathes exposed surfaces - cilia sweep debris/microorganisms trapped in mucus toward the pharynx; swallowed and - exposed to acids and enzymes of the stomach

8. Histology of the Respiratory Epithelium Figure 24.2 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

9. Upper Respiratory Structures • Nose – primary passageway for air normally entering through the paired external nares • Nasal cavity - nasal vestibule supported by thin, paired lateral cartilages and 2 pairs of alar cartilages - contains coarse hairs that trap large airborne particles - nasal septum formed by the fusion of the ethmoidal perpendicular plate and the vomer - mucous secretions produced by paranasal sinuses keep the cavity moist and clean • Pharynx – passageway connecting the nose, mouth, and throat - shared by the digestive and respiratory systems

10. Nasopharynx – superior portion - contains the pharyngeal tonsil - lateral walls contain the openings of the auditory tubes • Oropharynx – extends between the soft palate and the base of the tongue - epithelium changes to stratified squamous - contains the dangling uvula and 2 pairs of muscular pharyngeal arches - on either side a palatine tonsil lies between an anterior palatoglossal arch and a posterior palatopharyngeal arch - fauces, passageway between the oral cavity and the oropharynx • Laryngopharynx – region between the hyoid bone and entrance to the esophagus

11. Respiratory Structures Figure 24.3 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

12. Figure 24.3 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

13. Lower Respiratory Structures • Glottis - inspired air leaves the pharynx through this narrow opening • Larynx • Trachea • Bronchi • Bronchioles • Aveoli

14. Lower Respiratory Structures • Larynx – a cylinder begins at C4 or C5; ends at C7 - cartilaginous walls are stabilized by ligaments and skeletal muscles: - thyroid cartilage, largest forms most of the anterior (laryngeal prominence) and lateral walls - cricoid (‘ring-shaped’) cartilage, a complete ring - cricoid and thyroid cartilages protect the glottis and entrance to the trachea - epiglottis, shoehorn-shaped projection superior to the glottis, during swallowing the larynx is elevated and the epiglottis folds back over the glottis, stop food or liquid entry

15. Anatomy of the Larynx • Also contains 3 pairs of smaller cartilages: arytenoid (‘ladle-shaped’), corniculate (‘horn-shaped’), cuneiform (‘wedge-shaped’) Figure 24.4a

16. Laryngeal Ligaments Figure 24.4 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

17. The Vocal Cords Vocal ligament highly elastic tissue involved with the production of sound Figure 24.5

18. Movements of the Larynx during Swallowing Figure 24.6

19. Trachea

20. The Trachea • Also called the windpipe – tough, flexible tube ~2.5cm in diameter and ~11cm in length • Walls contain cartilage rings • Enters thoracic cavity anterior to esophagus • Bifurcates at the carina

21. The Primary Bronchi • Wall structure similar to tracheal wall • One per lung • The right primary bronchus supplies the right lung, and the left supplies the left lung • Right has a larger diameter and descends toward lung at steeper angle - makes it easier for foreign objects to get lodged

22. Anatomy of the Trachea and Primary Bronchi Figure 24.7 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

23. The Lungs • Lungs are divided into lobes: - 3 lobes on right: superior, middle, and inferior - 2 lobes on left: superior and inferior • Bronchi branch out into smaller bronchioles - bronchioles lead to alveoli

24. Superficial Anatomy of the Lungs Figure 24.8 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

25. Fig 24.8b Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

26. Bronchi and Bronchioles Figure 24.9

27. The Bronchial Tree and Divisions of the Lungs: d) Bronchial Divisions and Bronchopulmonary Segments Figure 24.10

28. Figure 24.10 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

29. Figure 24.10 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

30. Figure 24.11 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

31. Figure 24.11 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

32. Figure 24.12 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

33. Figure 24.16 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

34. The Pleural Cavities and Pleural Membranes • Parietal pleura lines the pleural cavity • Visceral pleura covers the lungs • Pleural fluid causes membranes to stick together but still slide on one another

35. Anatomical Relationships in the Thoracic Cavity Figure 24.13 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

36. Respiratory Muscles and Pulmonary Ventilation • Inspiratory muscles - diaphragm - external intercostal muscles • Expiratory muscles - usually not needed due to elastic recoil of lungs and thoracic cavity

37. Accessory respiratory muscles • Inspiration - sternocleidomastoid, serratus anterior, pectoralis minor, and scalene muscles • Expiration - transversus thoracis, oblique, and rectus abdominis muscles - internal intercostal muscles

38. Figure 24.14

39. Respiratory Centers and Reflex Controls Figure 24.15

40. Aging and the Respiratory System • Elastic tissue deteriorates, reducing the lungs’ ability to inflate and deflate • Movements of the rib cage are restricted by arthritic changes • Some degree of emphysema is normally found in individuals age 50–70