Gaseous Exchange in Animals

This section provides the opportunity for investigating how the human breathing system allows the exchange of fases between alveoli and the blood caplillaries. The effects of cigarette smoke on health are considered.

Structure of the Breathing System

Alveoli and Gasous Exchange

• There are millions of alveoli, therefore large surface area
• surfrace lining is moist, so gasses can dissolve before diffusing
• Thin membrance
• pulmonary artery brings deoxygenated blood
• pulmonary vein brings oxgenated blood
• diffusion of oxygen and carbon dioxide into and out of the blood

• Lining the nose and lungs are goblet cells, which produce mucus
• dirt and germs get caught in the mucus and is flicked up back to the mout by cilia.

• CO - reduces the oxygen carrying capacity of the blood
• Nicotine - is addictive, relaxes muscles, raises blood pressure, and increases fatty substances in the blood
• Smoking causes
• smokers cough - mucus gets caught in bronchioles cilia, and are too clogged up to flick mucus back up
• Bronchitis - bursts alveoli walls (emphesema) therefore a reduced area for oxygen and carbon dioxide to diffuse.
• Cancer - carcinogens in tobacco cause cells to divide more than they should. This causes a tumour.
• Heart Disease - tendencies for blood to clot will inrease, due to increased fat.
• Tar - clogs up cilia

• Intercostal muscles contract
• diaphragm moves down (contracts)
• Ribs move up and out
• Thorax volume increases, pressure decreases
• air drawn into lungs

• Intercostal muscles relax
• diaphragm reaxes
• Ribs move down and in
• Throax volume decreases, pressure increases
• air forced out of lungs

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