1. 6.4 Gas Exchange

2. Ventilation, Gas Exchange & Cellular Respiration
Ventilation: movement of air into and out of the lungs
Maintain concentration gradient between oxygen and carbon dioxide in the alveoli and blood capillary
Allows for simple diffusion of gases

4. Gas Exchange: exchange of carbon dioxide for oxygen that occurs in the alveoli of the lungs
Oxygen passes from the alveoli into the capillaries surrounding the alveoli
Carbon dioxide passes from the capillaries into the alveoli
The body needs oxygen to carry out cellular respiration

5. Cellular respiration: the controlled release of energy from organic molecules coupled with the production of ATP
Uses oxygen provided by ventilation to create energy
Also produces carbon dioxide that must be removed from the body

6. Concentration Gradient
Ventilation system must maintain a high concentration gradient across the alveoli to allow for sufficient gas exchange
Maintained by the amount of oxygen and carbon dioxide in the alveoli
High concentration of oxygen allows for the movement of the oxygen form the alveoli into the blood stream
Maintaining a low concentration of carbon dioxide allows for the movement of carbon dioxide from the capillaries into the alveoli

7. Pneumocytes (2 types)
Type I pneumocytes: elongated with very thin cells.
their shape helps with gas exchange
Type II pneumocytes: are thick and have short cells
They secrete a solution that has surfactant to ensure the membranes of the alveoli remain moist
Moisture ensures they don’t stick together
Helps facilitate a high rate of diffusion of respiratory gases

8. Pneumocytes

9. Features of Alveoli Feature Significance Many alveoli present
Increase surface are for more efficient gas exchange
Capillaries surround alveoli
Close association with capillaries allows for efficient gas exchange between capillaries and alveoli (gas needs to diffuse a short distance)
Alveoli are only one cell thick
Allows ease of diffusion across a small distance
Alveoli are moist
Moisture increases the rate of diffusion by dissolving the gases and also prevents alveoli from sticking together
Alveoli are flexible
Single cell layer can stretch and become thinner to facilitate rapid gas exchange

10. The Ventilation System
Includes the following parts:
Mouth
Nasal cavity
Epiglottis
trachea
Lungs
Bronchi
Bronchioles
Alveoli
diaphragm

11. Gas Exchange Inhale & Exhale
Based on pressure changes
Air moves from an area of high pressure to low pressure
Muscle
Inhalation
Exhalation
Diaphragm
Contracted (pulls downward)
Relaxed (bends upward)
Internal intercostals
Relaxed
Contracted (pulls ribs down & inward)
External intercostals
Contracted (pulls ribs up & outward)
Abdominal muscles
Relaxed and pushed out
Contracted & pull inwards

12. Lung Cancer and Emphysema
Causes
Consequences
Lung cancer
Cigarette smoke
Asbestos exposure
Radon gas
Exposure to air pollutants
Genetics
Persistent cough
Coughing up blood
Fatigue
Weight loss
Shortness of breath
Emphysema
Wheezing
Coughing

13. Lung cancer
Develops from cells that divide uncontrollably and destroy health lung tissue
Most prevalent & deadliest cancer among men & women
Number one cause cigarette smoke

15. Emphysema
Chronic respiratory disorder caused by damage to alveoli