GAS EXCHANGE

1 - (right) lung 2- larynx 3- trachea 4- bronchi 5- bronchioles 6 - intercostal muscle 7 - rib 8 - diaphragm 9-alveolus

• external intercostal muscles contract, pulling rib cage upwards and outward -Diaphragm contracts and flattens -As a result, thorax volume increases, causing pressure to decrease -Decrease in pressure causes air to be drawn into lungs = inhalation

-Internal intercostal muscles contract, pulling rib cage downwards and inwards -Diaphragm relaxes and forms dome shape -As a result, thorax volume decreases, causing pressure to increase -Increase in pressure causes air to be forced out of lungs = exhalation

1) FOLDED ALVEOLI = increase surface area to volume ratio for diffusion of gases, therefore increasing rate of gas exchange THIN CELL WALLS (one cell thick) = to minimise distance of diffusion of gases, therefore increasing the rate of gas exchange SURROUNDED BY DENSE CAPILLARY NETWORK = to provide rich blood supply and creates a strong concentration gradient for the diffusion of gases, therefore increasing the rate of gas exchange

EFFECT ON AIR PASSAGES = tar in cigarettes destroy the Cilia, therefore causing the buildup of Mucus and increasing risk of Bronchitis Tar in cigarettes contain carcinogens that increases risk of Lung Cancer EFFECT ON ALVEOLI = tar in cigarettes break down Alveoli walls and causes them to merge together, decreasing the surface area to volume ratio for gas exchange Insufficient gas exchange will increase the risk of Emphysema - shortness of breath due to insufficient Oxygen transport in blood

EFFECT ON CIRCULATORY SYSTEM: • Nicotine in cigarettes causes blood vessels to narrow, placing strain on circulatory system and results in the increase in blood pressure. • Narrowing of blood vessels also causes the build-up of Fat globules, increasing risk of Coronary Heart Disease (CHD) • CHD involves the blockage of Coronary Artery by Fat globules, causing insufficient Oxygen transport in blood leading to increased anaerobic respiration -Increase in anaerobic respiration causes build-up of Lactic acid which creates acidic environment for enzymes to denature, hence causing strokes -Carbon Monoxide from cigarette smoking will bind irreversibly to Haemoglobin, reducing capacity of Oxygen transport by Red blood cells and hence increases the risk of Emphysema - shortness of breath due to insufficient Oxygen transport in blood

Carbon Monoxide from cigarette smoking will bind irreversibly to Haemoglobin, reducing capacity of Oxygen transport by Red blood cells and hence increases the risk of Emphysema - shortness of breath due to insufficient Oxygen transport in blood

• Nicotine in cigarettes causes blood vessels to narrow, placing strain on circulatory system and results in the increase in blood pressure. • Narrowing of blood vessels also causes the build-up of Fat globules, increasing risk of Coronary Heart Disease (CHD)

-tar in cigarettes destroy the Cilia, therefore causing the buildup of Mucus and increasing risk of Bronchitis -Tar in cigarettes contain carcinogens that increases risk of Lung Cancer - tar in cigarettes break down Alveoli walls and causes them to merge together, decreasing the surface area to volume ratio for gas exchange -Insufficient gas exchange will increase the risk of Emphysema - shortness of breath due to insufficient Oxygen transport in blood

METHOD: Stationary breathing rate of participants is recorded Specific exercise will be performed by participants at the same intensity for a fixed period of time Breathing rate after exercise is recorded Results are compared RESULT: During exercise, more energy is needed via respiration to allow muscle contractions to occur to facilitate movement Hence, the rate of breathing will increase to allow more Oxygen transport in blood to respiring cells for movement to occur If energy demand exceeds Oxygen intake, energy may be produced via aerobic respiration, producing Lactic acid as a waste product After exercise, breathing rate continues to increase as extra Oxygen is needed to break down the Lactic acid produced - Oxygen debt