• A Drug is any substance taken into the body that modifies or affects chemical reactions in the body.

medicinal drugs

1) Describe the use of Antibiotics for Treatment of Bacterial Infection

• Antibiotic drugs are used to treat bacterial infections.
• Some antibiotics kill bacteria by destroying their cell wall, leading to the cell bursting, whilst others interfere with protein synthesis and inhibit the growth of the bacteria.

2) Explain how development of Resistant Bacteria can be minimised

• If a course of antibiotics is not completed, some of the bacteria may not be completely killed off.
  
• These remaining bacteria can undergo mutation and become resistant to the antibiotic.
  
• When they reproduce, all their offspring will have the drug resistance, so the antibiotic will become less effective.
• This can be prevented by only using antibiotics for serious infections, and always completing the full course of antibiotics to make sure all the bacteria is killed.

3) Explain why antibiotics kill Bacteria but not Virus

• Antibiotics work by disrupting the 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.

misused drugs

4) Describe Effects of Excessive Alcohol and Heroin Abuse

• Alcohol and heroin are both depressants, meaning that they lower the rate of nervous impulses by blocking synapses. This means that person's reactions are slower.
• Lower self-control can lead to increased crime rate and antisocial behaviour.
• These drugs also cause the release of neurotransmitters such as dopamine into synapses in the reward pathway which causes a ‘high’. This can be addictive and thus lead to withdrawal symptoms if the person stops taking the drug.
• Heroin is usually injected, thus infections such as HIV are common from sharing dirty needles.
• The liver is the site of break down of alcohol and other toxins. Excessive alcohol consumption can lead to liver damage.​​

5) Describe the Effects of Smoking on the Gas Exchange System

• Smoking is addictive due to a chemical called nicotine which is inhaled with the cigarette smoke and causes the release of dopamine. This leads to long-term smoking habits, which can cause many other diseases
  
• Chronic obstructive pulmonary disease (COPD):  a group of diseases that decrease the efficiency of gas exchange in the lungs by damaging the alveoli, decreasing the surface area for diffusion, and causing inflammation in the airways. COPD causes breathlessness, a persistent cough and frequent chest infections. The condition cannot be cured, although the progression can be slowed, and symptoms treated.
  
• Lung cancer:  this is because cigarette smoke contains a variety of toxic chemicals, many of them carcinogens.
  
• Carbon monoxide:  compete with oxygen to bind with haemoglobin. This means that there is less oxygen present in the blood so the heart must work harder to supply it to the tissues.
• Nicotine:  addictive, causes high heart rate and blood pressure, and also triggers the release of adrenaline.
  
• Tar:  when inhaled, sticks to the cilia of cells in the lungs which usually transport mucus away from the lungs to protect them from infections. Tar prevents them from doing this, which is why smokers are more susceptible to chest infections. In addition, a build-up of tar can narrow airways.​

6) Discuss the use of Hormones to improve Sporting Performance

• Some drugs are used to enhance sporting performance. In competitive sports, these drugs are seen as unfair and are usually banned, with those using them being disqualified.
  
• Anabolic steroids:  trigger the release of hormones which promote muscle mass and strength. Different types of steroids target different muscle groups.
  
• Testosterone:  is a hormone which enhances athletic performance by improving muscle strength and size, as well as increasing energy levels and hand-eye coordination.