DRUGS

Question 1

Drug

Answer 1

Any substance taken into the body that modifies or affects chemical reactions in the body Drugs .Drugs may be used to treat disease, reduce the sensation of pain or help calm us down. In addition, they may change our mood by affecting the brain.

Question 2

Medicinal drugs

Answer 2

Antibiotics destroy bacteria without harming the tissues of the patient. This makes them ideal for treating bacterial infections. Most of the antibiotics we use come from bacteria or fungi that live in the soil. One of the best-known antibiotics is penicillin, which is produced by the mould fungus Penicillium. Antibiotics attack bacteria in a variety of ways. Some of them prevent the bacteria from reproducing or even cause them to burst open; some interfere with protein synthesis to stop bacterial growth. Not all bacteria are killed by antibiotics. Some bacteria can mutate into forms that are resistant to these drugs, reducing the effectiveness of antibiotics. It is important to note that antibiotics do not affect viruses.

Question 3

Resistant bacteria

Answer 3

it is really important that the development of resistant bacteria is minimised, because otherwise antibiotics will become ineffective in the treatment of bacterial infections. MRSA (methicillin-resistant Staphylococcus aureus) is one bacterium that is resistant to antibiotics. It is sometimes called a ‘superbug’.

Question 4

To reduce the development of resistant bacteria

Answer 4

•antibiotics should be used only when essential, otherwise there could be a build-up of a resistant strain of bacteria. The drug resistance can be passed from harmless bacteria to pathogens • a course of antibiotics should always be completed and not used in a diluted form, or bacteria that have been exposed to the antibiotic but not killed may mutate into resistant forms.

Question 5

Antibiotics and viral diseases

Answer 5

Antibiotics are not effective against viral diseases. This is because antibiotics work by disrupting structures in bacteria such as cell walls and membranes, or processes associated with protein synthesis and replication of DNA. Viruses have totally different characteristics to bacteria, so antibiotics do not affect them.

Question 6

Alcohol and heroin

Answer 6

Depressants have a relaxing effect because they depress the central nervous system. In high doses, they can cause users to sleep or act as an anaesthetic, causing unconsciousness. You need to be able to describe the effects of alcohol and heroin, the dangers of their misuse and the personal and social problems they can cause.

Question 7

alcohol

Answer 7

Question 8

heroin

Answer 8

Question 9

Effects of tobacco smoking

Answer 9

Tobacco smoke contains a large number of toxic chemicals. The main ones are carbon monoxide, nicotine, smoke particles and tar. Note that these chemicals can affect various parts of the body, including the respiratory system and the circulatory system.

Question 10

carbon monoxide

Answer 10

Question 11

nicotine

Answer 11

Question 12

tar

Answer 12

Question 13

Chronic obstructive pulmonary disease (COPD)

Answer 13

This term covers a number of lung diseases, including chronic bronchitis, emphysema and chronic obstructive airways disease. A person suffering from COPD will experience difficulties with breathing, mainly because of narrowing of the airways (bronchi and bronchioles). Symptoms of COPD include breathlessness when active, frequent chest infections and a persistent cough with phlegm (sticky mucus).

Question 14

Role of the liver in the breakdown of drugs

Answer 14

The body treats alcohol as a poison. The liver removes poisons, such as alcohol and drugs, from the blood and breaks them down. Prolonged and excessive use of alcohol damages the liver and may cause it to fail. An overdose of drugs, such as paracetamol, can result in death owing to liver failure, because the liver cannot cope with breaking down such a high concentration of the chemical. The liver also converts hormones (some of which are misused as drugs) into inactive compounds. These are filtered out of the blood by the kidneys.

Question 15

How heroin affects the nervous system

Answer 15

Heroin produces its effects by interacting with receptor molecules at synapses (see Chapter 14). Synapses are tiny gaps between neurones, across which electrical impulses cannot jump. To maintain the transmission of the impulse, a chemical messenger called a neurotransmitter is released into the gap. Heroin mimics the transmitter substances in synapses in the brain, causing the stimulation of receptor molecules. This causes the release of dopamine (a neurotransmitter), which gives a short-lived ‘high’.

Question 16

Evidence for the link between smoking and lung cancer

Answer 16

The fact that a higher risk of dying from lung cancer is correlated with heavy smoking does not actually prove that smoking is the cause of lung cancer, but the weight of evidence supporting the link is now very great. Many scientific studies show, beyond all reasonable doubt, that the large increase in lung cancer is almost entirely a result of cigarette smoking. There are at least 17 substances in tobacco smoke known to cause cancer in experimental animals, and it is now thought that 90% of lung cancer is caused by smoking.

Question 17

Performance-enhancing hormones

Answer 17

These are used illegally by some athletes and sports to boost their performance. Some of these drugs are synthetic forms of hormones. Testosterone is made in the testes of males and is responsible for promoting male primary and secondary sexual characteristics. Taking testosterone supplements (known as ‘doping’) leads to increased muscle and bone mass. Therefore, the practice has the potential to enhance a sportsperson’s performance. Anabolic steroids are synthetic derivatives of testosterone. They affect protein metabolism, increasing muscle development and reducing body fat. Athletic performance is enhanced as a result. There are serious long-term effects of taking anabolic steroids, including sterility, masculinisation in women, and liver and kidney malfunction.