L8 - Smoking

objectives

• Understand the biological consequences of smoking in relation to the lungs and the circulatory system

Chemicals in Cigarettes

There are many harmful chemicals found in cigarettes:

Nicotine

• An addictive drug that affects the central nervous system.
• It increases the heart rate and narrows the blood vessels, causing high blood pressure.
• This can lead to heart disease.

Carbon Monoxide

• A poisonous gas that reduces the amount of oxygen that red blood cells carry around the body.
• It combines with haemoglobin in red blood cells, preventing the oxygen from combining with it.
• This also causes an increase in heart rate to compensate for the reduced oxygen-carrying capacity of the blood.
• This can lead to heart disease.

Cilia, Mucous and Tar

• Cells in the lining of the respiratory tract produce sticky mucus to trap dirt and microbes.
• Cells with tiny hair-like parts, called cilia, normally move the mucus out of the lungs.
• Tar is a brown, sticky substance that consists of tiny particles and is formed when tobacco smoke condenses.
• It is deposited in the lungs and coats the surface of the cilia making them non functional.
• This leads to a build up of mucus containing trapped pathogens.
• The pathogens can multiply in the warm and moist airways, leading to infection such as bronchitis.

Smoking causes Emphysema

• Smoke damages the delicate alveoli.
• They lose elasticity and the walls break down and fuse back together forming large, irregular air spaces.
• This reduces surface area for gas exchange.
• Gas exchange becomes very inefficient and sufferers struggle to carry out even the lightest of activities.