The Respiratory System

1. The Respiratory System Chapter 13

2. What is respiratory system responsible for? • Cells use of oxygen • Can’t do without it! • Waste products of aerobic respiration • CO2 • Cardiovascular and respiratory systems share job of providing O2 and removing CO2 • Gas exchange vs transport

3. Functional Anatomy • Nose, pharynx, larynx, trachea, bronchi, smaller branches and lungs which contain alveoli • Gas exchange with blood only happens in alveoli • All other structures just conducting passages Figure 13.1

4. The Nose • Only externally visible part • Nostrils or nares – air enters • Nasal cavity – inside • Nasal septum • Olfactory receptors • Where are they? Figure 13.2

5. Respiratory Mucosa of Nose • Lines nasal cavity • Covers network thin walled veins – blood flow warms air • Nose bleeds? • Moisten air, trap bacteria and debris • Lysozymes • Ciliated cells • Sluggish on cold days • Conchae – SA and turbulence • Palate – malformation? Figure 13.2

6. Sinuses • Paranasal sinuses – in frontal, sphenoid, ethmoid, and maxillary bones • Lighten skull • Resonance chamber for speech • Produce mucus • Nose blowing Figure 13.2

7. Diseases • Sinusitis – sinus inflammation • Passageways between sinus and nasal cavity blocked - mucus or infectious matter • Sinus headache • Rhinitis – cold virus or allergens cause inflammation of nasal mucosa • Nasal congestion and drip • Mucosa continuous throughout tract – leads to infections in nasolacrimal ducts and sinuses

8. Pharynx • Muscular passageway – throat • Food and air • Nasopharynx • Eustachian tubes drain here –leads to what? • Pharyngeal tonsil - adenoid • Oropharynx • Palatine tonsils • Lingual tonsils • Tosillitis • Laryngopharynx • Leaves here and enters larynx • Food enters esophagus Figure 13.2

9. Larynx • Voice box • Routes food and air • Formed by 8 hyaline cartilages – largest thyroid cartilage – adam’s apple • Epiglottis – elastic cartilage • When swallow, larynx pulled up, epiglottis tips, lid over larynx • Not swallowing, larynx open • Cough reflex – doesn’t work when unconscious • Vocal chords – vibrate with air movement Figure 13.2

10. Trachea • Windpipe • To 5th thoracic vert. • Rigid – walls reinforced with C shaped rings – hyaline cartilage • Rings • Open part to esophagus allows for expansion when swallow • Solid part keeps trachea open with pressure changes due to breathing

11. Trachea • Lined with ciliated mucosa • Beat continuously upward • Dust and other debris • Swallow or spat out • Smoking inhibits and destroys Figure 13.3

12. Main Bronchi • Branch from trachea into each lung • Rt. Bronchus is wider shorter and straighter • Choking • Air is warm, cleansed, and humidified Figure 13.1

13. Lungs • Occupy entire thoracic cavity except what? • Divided into lobes • Rt – three lobes • Lf – two lobes • Surface covered with visceral pleura • Walls of thoracic cavity – parietal pleura • Pleural space filled with pleural fluid • Two layers move smoothly, but resist being separated • Lungs held tightly to wall Figure 13.4a

14. In Lungs • Bronchi divide into smaller pathways • Smallest conducting pathway is bronchioles • Bronchioles eventually terminate in alveoli • Alveoli only site of gas exchange • Lungs mostly air spaces • Lungs only weigh 2.5 lbs Figure 13.5

15. Respiration • Pulmonary ventilation (breathing)– air movement in and out of lungs refreshing gas sacs (alveoli) • External respiration – gas exchange, O2 loading, CO2 unloading between pulmonary blood and alveoli. • Between blood and body exterior • Respiratory gas transport – O2 and CO2 transported to/from lungs and tissue cells of body via blood • Internal respiration – systemic capillaries, gas exchange between blood and tissue cells.

16. Mechanics of Breathing • Volume changes lead to pressure changes, which lead to the flow of gases to equalize the pressure. • In large, volume, gas molecules will spread out, reduced pressure • In smaller volume, gas molecules closer together, greater pressure • Intrapleural pressure is normally negative, prevents lung collapse Figure 13.4a

17. Inspiration • Inspiratory muscles – diaphragm and external intercostals • Contract, enlarge thoracic space • Lungs adhere to thoracic cavity • Intrapulmonary volume increases, decrease in pressure, sucks air in until intrapulmonary pressure equals atmospheric pressure Figure 13.7a

18. Expiration • Passive process in healthy • Inspiratory muscles relax • Thoracic and intrapulmonary space decreases • Intrapulmonary pressure greater than atmospheric – gas flows out! Figure 13.7b

19. Expiration in diseased • Spasms of bronchioles (asthma) or clogged with mucus or fluid (pneumonia) • Expiration active process • Internal intercostals compress • Abdominal muscles Figure 13.7b

20. Respiratory Volumes and Capacities • Factors affecting resp. capacity – size, sex, age, physical condition • Tidal Volume (TV)– normal breathing, about 500 ml in and out with each breath • Inspiratory Reserve Volume (IRV) – amount of air taken in forcibly, about 2100-3200 ml • Expiratory reserve volume (ERV) – forcibly exhaled air, about 1200 ml • Residual Volume – air that remains in lungs after forced exhale, about 1200 ml • Allow for continuous gas exchange • Vital Capacity (VC) – Total amount of exchangeable air. • TV+IRV+ERV • About 4800 ml in healthy young male Figure 13.9

21. Smokers vs Non-smokers A Closer Look

22. The End