1. Respiratory System – Chapter 8
The function of the respiratory system
We breathe so that the cells in our body receive oxygen to perform cellular respiration to keep us alive.
The respiratory system also functions to remove the waste products of cellular respiration from our bodies (carbon dioxide.)
The respiratory system is divided into two parts – the upper respiratory tract and the lower respiratory tract.
The membrane surrounding the chest cavity and lungs is called the pleura.

3. Components of the Upper Respiratory Tract

4. Mouth and Nose
Brings air into the body
Receptors for smell
Nasal hairs filter incoming air for things such as dust and pollen
Moistens and warms incoming air
Pharynx
Tube-like passageway used by food, liquid, and air
At the lower end of the pharynx is a flap of tissue called the epiglottis, which covers the trachea during swallowing so that food does not enter the lungs.

5. Components of the Lower Respiratory Tract

6. Lower Respiratory Tract
Larynx: Maintains an open airway, routes food and air appropriately, assists in sound production.
Trachea: Transports air to and from lungs; connects the larynx with the bronchi; lined with a mucus membrane and cilia.
Bronchi: Two short tubes that branch off of the trachea into the lungs; singular - bronchus.
Bronchioles: Tiny branches of air tubes in the lungs that connect the bronchi to the alveoli.
Alveoli: Tiny, thin-walled, grapelike clusters at the end of each bronchiole; Surrounded by capillaries; Where carbon dioxide and oxygen exchange take place; Singular – alveolus.
Diaphragm: Muscle wall between the chest and the abdomen that the body uses for breathing.

7. Gas Exchange Between the Blood and Alveoli

8. Respiratory Cycle
Figure 10.9

10. Disorders of Respiratory System
Reduced air flow: asthma, emphysema, bronchitis.
Infections: pneumonia, tuberculosis, botulism.
Lung cancer
Congestive heart failure
Cystic fibrosis

11. Process of Breathing: Pressure Gradient
Inspiration/Expiration: air in/air out
Cycle:
Relaxed state: Diaphragm and intercostal muscles relaxed.
Inspiration: Diaphragm contracts, pulling muscle down, intercostal muscles contract elevating chest wall and expanding volume of chest, lowering pressure in lungs, pulling in air.
Expiration: Muscles relax, diaphragm resumes dome shape, intercostal muscles allow chest to lower resulting in increase of pressure in chest and expulsion of air.

12. Gas Exchange & Transport: A Passive Process
Gases diffuse according to their partial pressures
External Respiration: Gases exchanged between air and blood
Internal Respiration: Gases exchanged with tissue fluids
Oxygen Transport: Bound to hemoglobin in red blood cells or dissolved in blood plasma
Carbon Dioxide Transport: Dissolved in blood plasma, bound to hemoglobin, or in the form of plasma bicarbonate

13. Regulation of Breathing: Nervous System Involvement
Respiratory center in the medulla oblongata: establishes basic breathing pattern
Chemical receptors: monitor carbon dioxide, hydrogen ions, and oxygen levels
Medulla: sensitive to hydrogen ions in cerebrospinal fluid resulting from carbon dioxide in blood

14. Four Respiration Processes
Breathing: air in to and out of lungs
External Respiration: gas exchange between air and blood
Internal Respiration: gas exchange between blood and tissues
Cellular Respiration: oxygen use to produce ATP, carbon dioxide as waste

15. Extra Resources