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