VENTILATION U 1 Ventilation maintains concentration gradients of

VENTILATION

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 O 2 maintaining a HIGH oxygen concentration inside the alveoli EXHALATION removes CO 2 keeping carbon dioxide concentrations LOW in alveoli.

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

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.

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

U 5 Muscle contraction causes the pressure changes inside thorax that force air in and out of the lungs to ventilate them. • 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 • Decrease in volume of thorax increases the air pressure • Air flows out from the lungs (HIGH PRESSURE) to the environment (LOW PRESSURE)

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.

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. • http: //en. wikipedia. org/wiki/Lung_cancer

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.

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