1. VENTILATION

2. Ventilation is the physical process of breathing.
U 1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air and alveoli and blood flowing in adjacent capillaries.
Ventilation is the physical process of breathing.
INHALATION replaces the diffused O2 maintaining a HIGH oxygen concentration inside the alveoli EXHALATION removes CO2 keeping carbon dioxide concentrations LOW in alveoli.

3. U 2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange.

4. U 3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.

5. U 4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles

6. Increased volume in thorax (chest cavity) lowers the pressure
U 5 Muscle contraction causes the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.
Decrease in volume of thorax increases the air pressure
Air flows out from the lungs (HIGH PRESSURE) to the environment (LOW PRESSURE)
Increased volume in thorax (chest cavity) lowers the pressure
Air flows in from environment (HIGH PRESSURE) into the lungs (LOW PRESSURE) to balance the pressure change

7.   U 6 Different muscles are required for inspiration and expiration because muscles only do work when they contract. A 3 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action.

8. A 1 Causes and consequences of lung cancer.
Lung cancer is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung.
The vast majority (80–90%) of cases of lung cancer are due to long-term exposure to tobacco smoke. About 10–15% of cases occur in people who have never smoked. These cases are often caused by a combination of genetic factors and exposure to radon gas, asbestos, or other forms of air pollution ,including second-hand smoke.

9. A 2 Causes and consequences of emphysema.
EMPHYSEMA the alvioli are damaged or destroyed, their walls break down and the sacs become larger.
These larger air sacs move less oxygen into the blood. This causes difficulty breathing or shortness of breath that gets worse over time.
After air sacs are destroyed, they cannot be replaced.
Leading cause is SMOKING.

10. NOS 1 Obtain evidence for theories- epidemiological studies have contributed to or understanding of the causes of the lung cancer.