The Respiratory System

1. The Respiratory System • Basic functions of the respiratory system • Breathing (Pulmonary Ventilation) – movement of air in and out of the lungs • Inhalation (inspiration) draws gases into the lungs. • Exhalation (expiration) forces gases out of the lungs. • Gas Conditioning – as gases pass through the nasal cavity and paransal sinuses, inhaled air becomes turbulent. The gases in the air are • warmed to body temperature • humidified • cleaned of particulate matter • Gas Exchange - respiration • Supplies body with oxygen • Disposes of carbon dioxide • Produces Sounds • Protects respiratory surfaces • Site for olfactory sensation

2. Respiration • Respiration – four distinct processes must happen • Pulmonary ventilation – moving air into and out of the lungs • External respiration – gas exchange between the lungs and the blood • Transport – transport of oxygen and carbon dioxide between the lungs and tissues • Internal respiration – gas exchange between systemic blood vessels and tissues

3. Functional Anatomy of the Respiratory System • Respiratory organs • Nose, nasal cavity, and paranasal sinuses • Pharynx, larynx, and trachea • Bronchi and smaller branches • Lungs and alveoli

4. Organs of the Respiratory System Figure 21.1

5. Respiratory System • Consists of • Respiratory muscles – diaphragm and other muscles that promote ventilation • Respiratory zone – site of external respiration – respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. • Conducting zones • Provides rigid conduits for air to reach the sites of gas exchange • Includes nose, nasal cavity, pharynx, trachea • Air passages undergo 23 orders of branching in the lungs

6. The Nose • Provides an airway for respiration • Moistens and warms air • Filters inhaled air • Resonating chamber for speech • Houses olfactory receptors • Skin is thin – contains many sebaceous glands

7. The Nasal Cavity • External nares – nostrils • Divided by – nasal septum • Vestibule - anterior opening • Continuous with nasopharynx • Two types of mucous membrane • Olfactory mucosa - Near roof of nasal cavity, houses olfactory (smell) receptors • Respiratory mucosa - Lines nasal cavity • Epithelium is pseudostratified ciliated columnar • Goblet cells within epithelium • Underlying layer of lamina propria has glands that contribute to the mucus layer and blood vessels that warm the air. • Cilia move contaminated mucus posteriorly

8. Nasal Cavity

9. Nasal Conchae • 3 paired bony projections along the lateral walls of the nasal cavity • Superior and middle nasal conchae - part of the ethmoid bone • Inferior nasal conchae - separate bone • Function - Particulate matter deflected to mucus-coated surfaces

10. The Paranasal Sinuses Figure 7.11a, b

11. The Pharynx • Funnel-shaped passageway • Connects nasal cavity and mouth • Shared by the digestive and respiratory systems • Divided into three sections by location • Nasopharynx – superior portion, • Oropharynx – continuous with the oral cavity • Laryngopharynx – between the hyoid bone and the esophagus • Type of mucosal lining changes along its length

12. The Nasopharynx • Superior to the point where food enters • Only an air passageway • Closed off during swallowing • Epithelium consists of ciliated pseudostratified epithelium that moves mucus

13. The Oropharynx • Arch-like entranceway – fauces • Extends from soft palate to the epiglottis • Epithelium - stratified squamous epithelium • Two types of tonsils in the oropharynx • Palatine tonsils – in the lateral walls of the fauces • Lingual tonsils – covers the posterior surface of the tongue

14. The Laryngopharynx • Passageway for both food and air • Epithelium - stratified squamous epithelium • Continuous with the esophagus and larynx

15. The Larynx • Prevent food and drink from entering the trachea • Passageway for air • Produces Sound • It connects the pharynx to the trachea • Epithelium of the larynx • Stratified squamous – superior portion • Pseudostratified ciliated columnar – inferior portion

16. Nine Cartilages of the Larynx • Thyroid cartilage - shield-shaped, forms laryngeal prominence (Adam’s apple) • Three pairs of small cartilages • Arytenoid cartilages • Corniculate cartilages • Cuneiform cartilages • Epiglottis - tips inferiorly during swallowing

17. The Larynx • Vocal ligaments of the larynx • Vocal folds (true vocal cords) - act in sound production • Vestibular folds (false vocal cords) - no role in sound production • Voice production • Length of the vocal folds changes with pitch • Loudness depends on the force of air across the vocal folds

18. The Trachea • Descends into the mediastinum • C-shaped cartilage rings keep airway open • Carina - marks where trachea divides into two primary bronchi • Epithelium - pseudostratified ciliated columnar

19. The Trachea Figure 21.7a, b

20. Bronchi in the Conducting Zone • Bronchial tree - extensively branching respiratory passageways • Primary bronchi (main bronchi) • Largest bronchi • Right main bronchi - wider and shorter than the left • Secondary (lobar) bronchi • Three on the right • Two on the left • Tertiary (segmental) bronchi - branch into each lung segment • Bronchioles - little bronchi, less than 1 mm in diameter • Terminal bronchioles - less than 0.5 mm in diameter

21. Tissue Composition of Conducting Zone • Changes along pathway • Supportive connective tissues change • C-shaped rings – trachea, primary bronchi • Replaced by cartilage plates, secondary & tertiary bronchi • Epithelium changes • First, pseudostratified ciliated columnar – trachea • Replaced by simple columnar - bronchi • Then simple cuboidal epithelium - bronchioles and terminal bronchioles • Smooth muscle becomes important at the bronchioles - controlled by the ANS (bronchoconstriction and bronchodilation).

22. Lobes and Surfaces of the lungs • Right lung has three lobes • Left lung has two lobes • Concavity on medial surface = cardiac notch • Bronchi enter the lungs at the hilus

23. The Pleurae • A double-layered sac surrounding each lung • Parietal pleura • Visceral pleura • Pleural cavity - potential space between the visceral and parietal pleurae • Pleurae help divide the thoracic cavity • Central mediastinum • Two lateral pleural compartments

24. Structures of the Respiratory Zone • Consists of air-exchanging structures • Respiratory bronchioles – branch from terminal bronchioles • Lead to alveolar ducts • Lead to alveolar sacs

25. Structures of the Respiratory Zone Figure 21.9b

26. Features Of Alveoli • Alveoli cell types • Type I cells site of gas exchangeand • Type II cells - secrete surfactant • Macrophages • Surrounded by basal laminae and elastic fibers • Interconnect by way of alveolar pores • Internal surfaces - site for free movement of alveolar macrophages Figure 21.10b