Respiratory System: Functions and Structures

1. Chapter 21 Respiratory System

2. Respiratory zone • Site of gas exchange • Consists of bronchioles, alveolar ducts, and alveoli • Conducting zone • Provides rigid conduits for air to reach the sites of gas exchange • Includes all other respiratory structures (e.g., nose, nasal cavity, pharynx, trachea) • Respiratory muscles • diaphragm and other muscles that promote ventilation

3. Quiz Picture p. 701 Figure 22.1

4. 4 Processes of Respiration • Pulmonary ventilation – moving air into and out of the lungs (breathing) • External respiration – gas exchange between the lungs and the blood • Transport of respiratory gases – Oxygen and Carbon dioxide transport in blood • Internal respiration – gas exchange between systemic blood vessels and tissues

5. Functions of the Nose • Providing an airway for respiration • Moistening & warming incoming air • Filtering inspired air • Resonating chamber for speech • Contains olfactory receptors

6. Quiz Picture

7. Structure of the Nose • Nasal cavity • Mucous membranes • Olfactory Mucosa- • lines superior region of nose • (olfactory receptors=smell) • Respiratory Mucosa- ciliated pseudostratified columnar epithelial • goblet cells, mucous and serous glands • Secrete 1 qt mucus/day • Lysozyme – antibacterial enzyme • Traps foreign debris and cilia moves to throat • Mucosa-Have rich vascular supply-warm air • Conchae- makes air turbulent- increases mucosal surface area

8. Homeostatic Imbalance Rhinitis • inflammation of nasal mucosa - Mucus build up, stuffy nose

9. Paranasal Sinuses • Surround nasal cavity • Lighten the skull and help to warm and moisten the air • Mucus drains into nasal cavity

10. Homeostatic Imbalance Sinusitis • inflammation of sinus mucosa, infection of mucus in sinus -Swelling prevents movement of mucus out of sinuses = pressure -Sinus headache

12. Structure of the Nose Quiz Picture p. 702 Figure 22.2b

13. Pharynx • Connects nasal cavity to larynx and esophagus • Throat (5”) • Skeletal muscle • 3 regions

14. Nasopharynx – Air only • Goblet cells produce mucus • Swallowing- uvula closes off nasopharynx • Contains pharyngeal tonsils • Oropharynx – Food and Air • Continuous with nasopharynx • Contains palatine and lingual tonsils • Laryngopharynx – Air and Food • During swallowing food has priority

16. Larynx (Voice Box) Voice Box Superiorly attaches to hyoid bone, inferiorly with trachea Functions: • To provide an opening from pharynx to trachea • To act as a switching mechanism to route air and food into the proper channels • To make sound

17. Framework of the Larynx • Cartilages (hyaline) of the larynx • Thyroid cartilage with a midline laryngeal prominence (Adam’s apple) • Cricoid cartilage- below thyroid cartilage • Epiglottis – elastic cartilage (valve) that covers the entrance to larynx during swallowing • Glottis-opening between vocal cords • Normally open-closed swallowing

19. Framework of the Larynx True Vocal Cord- sound production – elastic fibers False Vocal Cords- Closed when swallowing Figure 21.4a, b

21. Vocal Production • Speech – intermittent release of expired air while opening and closing the glottis • Pitch – determined by the length and tension of the vocal cords • Loudness – depends upon the force at which the air rushes across the vocal cords • The pharynx resonates, amplifies, and enhances sound quality • Sound is “shaped” into language by action of the pharynx, tongue, soft palate, and lips

22. Movements of Vocal Cords Figure 21.5

23. Homeostatic Imbalance Laryngitis • inflammation of vocal cords -Swelling prevents movement -Overuse, dry air, bacteria, pollutants

24. Trachea • Flexible and mobile tube • Larynx to the primary bronchi • Composed of three layers • Mucosa – made up of goblet cells and ciliated epithelium –smoking destroys cilia • Submucosa – connective tissue deep to the mucosa • Adventitia – outermost layer made of C-shaped rings of hyaline cartilage- keeps open during inspiration

25. Trachea Figure 22.6a

27. Bronchi and Bronchioles (Conducting) • Right and left primary bronchi-formed by division of trachea • Air reaching the bronchi is: • Warm and cleansed of impurities • Saturated with water vapor • Bronchi subdivide into secondary bronchi, each supplying a lobe of the lungs • Air passages undergo 23 orders of branching in the lungs

28. Conducting Zone: Bronchial Tree • Tissue walls of bronchi mimic that of the trachea • As conducting tubes become smaller, structural changes occur • Cartilage support structures change • Epithelium types change • Amount of smooth muscle increases • Bronchioles • Consist of cuboidal epithelium • Have a complete layer of circular smooth muscle • Lack cartilage support and mucus-producing cells

30. Respiratory Zone • Presence of alveoli; begins as terminal bronchioles feed into respiratory bronchioles • Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs composed of alveoli • Approximately 300 million alveoli: • Account for most of the lungs’ volume • Provide tremendous surface area for gas exchange

31. Respiratory Zone Figure 22.8a

32. Respiratory Membrane Figure 22.9b

33. Cells within Alveoli • Type I cells -simple squamous epithelium, simple diffusion • Dust cells – alveolar macrophages • Type II cells – secrete surfactant • Reduces alveolar surface tension • Coats membrane

34. 1. Alveoli 2. Alveolar sac  3. Simple squamous epithelium  4. Blood vessel

35. Respiratory Membrane Figure 22.9.c, d

36. Surfactant • Surface tension – the attraction of liquid molecules to one another at a liquid-gas interface • The liquid coating the alveolar surface is always acting to reduce the alveoli to the smallest possible size • Detergent –like lipoprotein • Breaks up water molecules • Increases surface area of alveoli

37. Gross Anatomy of the Lungs • Left lung – separated into upper and lower lobes by the oblique fissure • Right lung – separated into three lobes by the oblique and horizontal fissures • Apex – under clavicle • Base – rests on the diaphragm • Hilum – medial surface of each lung-entrance /exit point

39. Blood Supply to Lungs • Pulmonary arteriesand veins – supply systemic venous blood to be oxygenated and then back to heart • Bronchial arteries – nourish lungs • Arise from aorta • Supply all lung tissue except the alveoli • Bronchial veins – drain lungs

40. Coverings of Lungs • Pleura - Thin, double-layered serosa • Visceral pleura – inner membrane • Covers external lung surface • Parietal pleura – outer membrane • Covers the thoracic wall and superior face of the diaphragm • Continues around heart and between lungs Pleura Fluid -serous fluid (lubrication) • Pleural cavity

41. Homeostatic Imbalance Pleurisy • Inflammation of pleural membranes • Friction and sticking of membranes • Feels like heart attack

42. Boyle’s Law Small Volume Gas Flow to Equalize the Pressure Large Volume = Change in Pressure = High Pressure Low Pressure • Inspiration – air flows into the lungs • Expiration – air leaves lungs

43. 3 Types of Pressure • Atmospheric – exerted by air surrounding the body • Sea level 760 mm Hg • Intrapulmonary – within alveoli • Equalized with atmospheric pressure • Intrapleural - in pleural cavity • Negative • Less than intrapulmonary pressure-keeps lungs expanded

44. Pressure Relationships

45. How lungs adhere to chest wall • Intrapulmonary pressure > Intrapleural pressure • Atmospheric pressure > Intrapleural Pressure • Causes adhesion of pleural membranes

46. Lung Collapse (Atelectasis) Homeostatic Imbalance Intrapleural pressure > Intrapulmonary pressure • Pneumothorax- • Knife wound, gun shot • Air moves into pleural cavity • May affect only one lung • Treatment: Close hole and draw air out.

47. Inspiration • Diaphragm and external intercostal muscles (inspiratory muscles) contract = Rib cage rises • Lungs are stretched and intrapulmonary Volume increases • Intrapulmonary pressure decreases below atmospheric pressure (1 mm Hg) • Air flows in the lungs, down its pressure gradient, until intrapleural pressure = atmospheric pressure

48. Expiration • Inspiratory muscles relax and the rib cage descends due to gravity • Thoracic cavity Volume decreases • Elastic lungs recoil passively = intrapulmonary Volume decreases • Intrapulmonary Pressure rises above atmospheric pressure (+1 mm Hg) • Gases flow out of the lungs down the pressure gradient until intrapulmonary pressure is equal to atmospheric

49. Inspiration and Expiration Figure 21.13

50. Respiratory Volumes –measured directly with spirometer • Tidal volume (TV) – air that moves into and out of the lungs with each breath (approximately 500 ml) • Inspiratory reserve volume (IRV) – air that can be inspired forcibly beyond the tidal volume (2100–3200 ml) • Expiratory reserve volume (ERV) – air that can be evacuated from the lungs after a tidal expiration (1000–1200 ml) • Residual volume (RV) – air left in the lungs after strenuous expiration (1200 ml)