Chapter 23: The Respiratory System

1. Chapter 23: The Respiratory System Primary sources for figures and content: Marieb, E. N. Human Anatomy & Physiology. 6th ed. San Francisco: Pearson Benjamin Cummings, 2004. Martini, F. H. Fundamentals of Anatomy & Physiology. 6th ed. San Francisco: Pearson Benjamin Cummings, 2004.

2. The primary functions of the respiratory system.

3. The Respiratory System • Cells produce energy: • for maintenance, growth, defense, and division • through mechanisms that use oxygen and produce carbon dioxide

4. Oxygen • Is obtained from the air by diffusion across delicate exchange surfaces of lungs • Is carried to cells by the cardiovascular system which also returns carbon dioxide to the lungs

5. 5 Functions of the Respiratory System • External respiration: - Provides extensive gas exchange surface area between air and circulating blood • Pulmonary ventilations • Moves air to and from exchange surfaces of lungs • Protects respiratory surfaces from outside environment - dehydration, temperature changes, invasion by pathogens • Produces sounds for communication • Provide olfactory sensation = Smell

6. Components of the Respiratory System Figure 23–1

7. Organization of the Respiratory System • The respiratory system is divided into the upper respiratory system, above the larynx, and the lower respiratory system, from the larynx down

8. Anatomy of Respiratory System 1. Upper Respiratory System • Function to warm and humidify air • Nose, nasal cavity, sinuses, pharynx 2. Lower Respiratory System • Conduction portion • Bring air to respiratory surfaces • Larynx, trachea, bronchi, bronchioles • Respiratory portion • Gas exchange • Alveoli

9. Alveoli • Are air-filled pockets within the lungs • where all gas exchange takes place

10. The Respiratory Epithelium Figure 23–2

11. Respiratory Mucosa = mucus membrane • Lines conducting portion of respiratory system • Epithelial layer: • pseudostratified columnar epithelium • Usually ciliated • Scattered goblet cells = mucin production • Areolar layer = lamina propria (trachea, bronchi) • Areolar connective tissue • Mucus glands = mucin • Serous glands = lysozyme • Glands produce ~1 quart mucus fluid/day • Cilia move mucus to pharynx to be swallowed • Cilia beat slow in the cold

12. Alveolar Epithelium • Is a very delicate, simple squamous epithelium • Contains scattered and specialized cells • Lines exchange surfaces of alveoli

13. The Respiratory Defense System • Consists of a series of filtration mechanisms • Removes particles and pathogens

14. Components of the Respiratory Defense System 1. Mucus • From goblet cells and glands in lamina propria, traps foreign objects 2. Cilia “mucus escalator” • Move carpet of mucus with trapped debris out of the respiratory tract 3. Alveolar macrophages • Phagocytose particles that reach alveoli 4. Filtration in nasal cavity removes large particles

15. Disorders of theRespiratory Defense System 1. Cystic fibrosis • Cause  Failure of mucus escalator • Result  Produce thick mucus which blocks airways and encourages bacteria growth 2. Smoking  destroys cilia 3. Inhalation of irritants  chronic inflammation  cancer e.g. squamous cell carcinoma

16. The upper respiratory system and their functions.

17. The Upper Respiratory System • Nose • Nasal Cavity • Pharynx • -Nasopharynx • -Oropharynx • -Laryngopharynx Figure 23–3

18. 1. The Nose • Only external feature • Air enters the respiratory system: • through external nares • into nasal vestibule • Space in flexible part, lined with hairs to filter particles, leads to nasal cavity • Nasal hairs in nasal vestibule are the first particle filtration system

19. 1. The Nose • Functions • Opening to airway for respiration • Moisten and warm entering air • Filter and clean inspired air • Resonating chamber for speech • Houses olfactory receptors

20. 2. The Nasal Cavity • The nasal septum: • divides nasal cavity into left and right • Superior portion of nasal cavity is the olfactory epithelium  provides sense of smell • Nasal conchae (superior, middle, inferior) project into cavity on both sides • Nasal conchae cause air to swirl • Increase likelihood of trapping foreign material in mucus • Provide time for smell detection • Provide time and contact to warm and humidify air

21. 2. The Nasal Cavity • Hard and soft palate form floor • Internal nares open to nasopharynx • Mucosa has large superficial blood supply • Function  warm, moisten air • Epistaxis = nose bleed • Paranasal sinuses in frontal, sphenoid, ethmoid, and maxillary bones • Lined with respiratory mucosa • Connected to nasal cavity • Aid in warming/moistening air

22. 2. The Nasal Cavity • Hard palate: • forms floor of nasal cavity • separates nasal and oral cavities • Soft palate: • extends posterior to hard palate • divides superior nasopharynx from lower pharynx • Air flow  Nasal cavity opens into nasopharynx through internal nares

23. 3. The Pharynx • A chamber shared by digestive and respiratory systems • Extends from internal nares to entrances to larynx and esophagus • Three Parts: • Nasopharynx • Oropharynx • Laryngopharynx

24. 3. The Pharynx • Nasopharynx = air only • Posterior to nasal cavity • Pseudostratified columnar epithelium • Closed off by soft palate and uvula during swallowing • Pharyngeal tonsil located on posterior wall • Inflammation can block airway • Auditory tubes open here 2. Oropharynx = food and air • Posterior to oral cavity • Stratified squamous epithelium • Palatine and lingual tonsils in mucosa

25. 3. The Pharynx 3. Laryngopharynx = food and air • Lower portion • Stratified squamous epithelium • Continuous with esophagus

26. Why is the vascularization of the nasal cavity important? It heats incoming air. It moisturizes incoming air. It nourishes nasal epithelial cells. All of the above.

27. Why is the lining of the nasopharynx different from that of the oropharynx and the laryngopharynx? Nasopharynx lining is not subjected to food abrasion. Nasopharynx lining must withstand temperature extremes. Nasopharynx must be protected from drying out. All of the above.

28. The lower respiratory system and their functions.

29. Air Flow • From the pharynx enters the larynx: • a cartilaginous structure that surrounds the glottis

30. 4. Larynx Figure 23–4

31. 4. Larynx = voice box • Hyaline cartilage around glottis • Opening form laryngopharynx to trachea • Functions of larynx • Provide continuous airway • Act as switch to route food and air properly • Voice production • Contains epiglottis • Elastic cartilage flap  covers glottis during swallowing

32. The Glottis Figure 23–5

33. 4. Larynx = voice box • Folds of epithelium over ligaments of elastic fibers create focal folds/cords • Vocal cords project into glottis • Air passing through glottis vibrates folds producing sound • Pitch  Controlled by tensing/relaxing of the cords • Tense + narrow = high pitch • Volume  Controlled by the amount of air • Sound Production  phonation

34. 4. Larynx = voice box • Speech • Formation of sound using mouth and tongue with resonance in pharynx, mouth, sinuses and nose • Laryngitis • Inflammation of vocal folds • Cause  infection or overuse that can inhibit phonation

35. When the tension in your vocal folds increases, what happens to the pitch of your voice? It rises. It falls. Nothing happens. It squeaks and cracks.

36. 5. Trachea Figure 23–6

37. The Trachea • Attached inferior to larynx • Walls composed of three layers 1. Mucosa • Pseudostratified columnar epithelium, goblet cells, lamina propria, smooth muscle and glands 2. Submucosa • CT with additional mucus glands 3. Adventitia • CT with hyaline cartilage rings (15-20)  keep airway open, C-shaped • Opening toward the esophagus to allow expansion, ends connected by trachealis muscle

38. 6. Primary Bronchi • Trachea branches into the Right and left primary bronchi • Similar structure as trachea • No trachealis muscle • Right = steeper angle • Enter lungs at groove (hilus) • Along with blood and lymphatic

39. Hilus • Where pulmonary nerves, blood vessels, and lymphatics enter lung • Anchored in meshwork of connective tissue

40. Gross Anatomy of the Lungs Right = 3 lobes Left = 2 lobes Figure 23–7

41. 6. Primary Bronchi • Lungs have lobes separated by deep fissures • Inside lungs bronchi branch, get smaller in diameter • Branch ~23 times creating the bronchial tree • As bronchi get smaller, structure changes • Less cartilage in adventitia • More smooth muscle in lamina propria • Epithelium is thinner, less cilia, less mucus

42. Bronchitis • Inflammation of bronchial walls: • causes constriction and breathing difficulty

43. Relationship between Lungs and Heart Figure 23–8

44. 7. Terminal bronchiole Smallest bronchi of Respiratory Tree Figure 23–9

45. 7. Terminal bronchiole • Smallest Bronchi • No cartilage • Last part of conduction portion • Trachea, Bronchi and Bronchioles innervated by ANS to control airflow to the lungs • ANS Regulates smooth muscle: • controls diameter of bronchioles • controls airflow and resistance in lungs • Sympathetic  bronchodilation • Parasympathetic  bronchocontriction • histamine release (allergic reactions)

46. Asthma • Excessive stimulation and bronchoconstriction • Activated by inflammatory chemicals (histamine) • Stimulation severely restricts airflow • Epinephrine inhaler mimics sympathetic ANS  bronchodilation

47. 7. Terminal bronchiole • Each terminal bronchiole delivers air to one pulmonary lobule, separated by CT • Inside lobule, terminal bronchiole branches into respiratory bronchioles • No cilia or mucus • Each respiratory bronchiole connects to alveolar sac made up of many alveoli

48. The Bronchioles Figure 23–10

49. 8. Alveoli Figure 23–11

50. 8. Alveoli • Wrapped in capillaries • Held in place by elastic fibers • Three cell types 1. Type 1 cells = gas exchange • Simple squamous epithelium, lines inside 2. Type II cells = surfactant • Cuboidal epithelial cells produce surfactant • Phospholipids + proteins • Prevent alveolar collapse, reduces surface tension 3. Alveolar macrophages = Phagocytosis • Phagocytosis of particles