Alcohol and smoking (AQA GCSE Biology): Revision Notes
Alcohol and smoking
Drinking alcohol and smoking are lifestyle risk factors. This means they are choices people make that can increase their chances of getting certain non-communicable diseases.
Effects of alcohol
Ethanol is the type of alcohol found in alcoholic drinks like beer, wine and spirits.
Ethanol is the active ingredient in all alcoholic beverages, regardless of whether it's beer, wine, or spirits. The concentration varies, but the substance causing the effects is always the same.
Short-term effects of drinking alcohol
When someone drinks a lot of alcohol in one go, it can cause immediate problems:
- Blurred vision - makes it hard to see clearly
- Slow reactions - takes longer to respond to things
- Lowered inhibitions - makes people take more risks and make poor decisions
These effects make alcohol dangerous because they affect how well someone can drive or make safe choices. Even small amounts of alcohol can impair judgement and reaction times.
Long-term effects of drinking alcohol
Drinking lots of alcohol over many months and years causes serious damage to the body:
- Brain damage - alcohol can permanently harm brain cells
- Liver cirrhosis - the liver becomes scarred and stops working properly
The liver is especially affected because it has to break down all the alcohol in the body.
The liver can only process about one unit of alcohol per hour. When people drink faster than this, alcohol builds up in the bloodstream and body tissues, causing damage over time.
Effects during pregnancy
When pregnant women drink alcohol, it can seriously harm the developing baby:
- Poor growth - the baby may not grow to normal size
- Abnormal facial features - the baby's face may not develop normally
- Behaviour and learning problems - the child may struggle at school and have difficulty controlling behaviour
No Safe Level: There is no known safe level of alcohol consumption during pregnancy. The more alcohol consumed during pregnancy, the greater the risk of these problems.
Effects of smoking
Tobacco smoke contains many harmful substances that damage the body.
Key harmful substances in cigarettes
Nicotine is the substance that makes smoking addictive. Once someone starts smoking, nicotine makes it very hard to stop.
Carbon monoxide is a poisonous gas that reduces how much oxygen the blood can carry. This means less oxygen gets to body organs.
Tar contains chemicals called carcinogens. These cause cancers, especially cancer of the mouth and lungs.
How Carbon Monoxide Affects Oxygen Transport:
Step 1: Normally, oxygen binds to haemoglobin in red blood cells Step 2: Carbon monoxide binds to haemoglobin 200 times more readily than oxygen Step 3: This prevents oxygen from binding, reducing oxygen delivery to tissues Result: Organs receive less oxygen, leading to health problems
Health problems from smoking
Smoking causes many serious diseases:
- Cardiovascular diseases such as heart attacks and strokes happen because substances in cigarettes make blood vessels narrower and increase blood pressure
- Cancer - the carcinogens in tar can cause cancers throughout the body
- Low birth weight babies - if pregnant mothers smoke, their babies are often born smaller than normal
Smoking affects almost every organ in the body. The chemicals in tobacco smoke enter the bloodstream and are carried throughout the body, which is why smoking can cause such a wide range of health problems.
Understanding correlations
Scientists study the link between alcohol consumption and disease. When they find that as alcohol consumption increases, liver disease also increases, this is called a positive correlation.
Sometimes you might see a negative correlation - this is when one factor increases while another decreases.
Understanding Positive Correlation:
Scientists collected data from thousands of people over 20 years:
- Group A: 0-1 drinks per week → 2% developed liver disease
- Group B: 2-7 drinks per week → 8% developed liver disease
- Group C: 8+ drinks per week → 25% developed liver disease
This shows a positive correlation: as alcohol consumption increases, liver disease rates also increase.
Key Points to Remember:
- Ethanol is the alcohol in drinks that causes both short-term and long-term health problems
- Short-term alcohol effects: blurred vision, slow reactions, lowered inhibitions
- Long-term alcohol effects: brain damage and liver cirrhosis
- Smoking contains harmful substances: nicotine (addictive), carbon monoxide (reduces oxygen), tar (causes cancer)
- Both alcohol and smoking are lifestyle risk factors that increase the chance of serious diseases