Chapter 19 – Respiratory System

1. Chapter 19 – Respiratory System Why We Breathe Organs – Nose, Nasal Cavity, Sinuses

2. What is respiration? • The exchange of gases between the atmosphere and the body cells

3. Respiration Includes: • Ventilation • Movement of air in and out of lungs

4. Respiration Includes: • External respiration • Exchange of gases between the air in the lungs and the blood

5. Respiration Includes: • Transportation of gases by the blood between the lungs and body cells

6. Respiration Includes: • Internal respiration • Exchange of gases between the blood and the body cells

7. Respiration Includes: • Cellular respiration • Use of oxygen and production of carbon dioxide by body cells

8. Why do we breathe? • During aerobic cellular respiration: • Cells produce ATP (adenosine triphosphate) by removing electrons from food molecules and sending them down the electron transport chain • Oxygen is needed for this process because electrons bind oxygen atoms and hydrogen ions to produce water at the end of the electron transport chain

9. Why do we breathe? • During aerobic cellular respiration: • Carbon dioxide is produced as a waste product • Small amounts of carbon dioxide are needed by the body to bind to water and form carbonic acid (which helps to maintain blood pH) but excess carbon dioxide must be eliminated

10. Organs of the Respiratory System • Upper respiratory tract • Nose, nasal cavity, sinuses, pharynx • Lower respiratory tract • Larynx, trachea, bronchial tree, lungs

11. Nose • Provides openings (nostrils) through which air enters and leaves the nasal cavity • Openings are guarded by internal hairs that prevent the entry of large particles • Covered by skin • Supported internally by muscle, bone, and cartilage

12. Nasal Cavity • Hollow space behind the nose • Conducts air to and from the nasopharynx • Contains the olfactory receptors (located in the upper posterior portion below the cribriform plate of the ethmoid bone)

13. Nasal Cavity • Structure • Separated into right and left portions by the nasal septum • Separated from the cranial cavity by the cribriform plate of the ethmoid bone • Separated from the oral cavity by the hard palate

14. Nasal Cavity • Structure • Nasal conchae • Thin bones that curl out from the lateral walls of the nasal cavity • Divide the nasal cavity into the superior, middle, and inferior meatuses (passageways) • Support and increase the surface area of the mucous membrane that lines the nasal cavity

15. Nasal Cavity • Structure • Mucous membrane • Lines the nasal cavity • Contains many goblet cells (secrete mucous) • Has an extensive network of blood vessels • (Heat from the blood in these vessels warms incoming air to body temperature and moistens the cavity through evaporation of water from the mucous layer.) • Is ciliated • (Cilia push a thin layer of mucus (along with any particles trapped in it) toward the pharynx where it is swallowed and sent to the stomach where any microorganisms it contains are destroyed by gastric juice.)

16. Nasal Cavity

17. Sinuses • Air-filled spaces in the maxillary, frontal, ethmoid, and sphenoid bones of the skull • Reduce the weight of the skull • Serve as resonance chambers that affect the quality of the voice • Are lined with mucous membranes that are continuous with the lining of the nasal cavity • Mucus secretions drain from the sinuses to the nasal cavity • If the drainage becomes blocked due to infections or allergies, pressure builds up in the sinus creating headaches