B1b.4.1 TB in London• tubercolosis [TB] is a disease caused by bacteria• TB bacteria are mycobacteria• mycobacteria can be dormant in the body for years• TB is spread through air
• AIDS is caused by the HIV virus• AIDS destroys the body’s immune system• c. 50% of AIDS sufferers will get TB
B1b.4.2 Controlling tuberculosis• drugs are substances which change the way the body works• antibiotics are drugs that kill bacteria• bacteria develop resistance to antibiotics• new drugs are tested for years before being approved for trials on humans• BCG is the vaccine against TB
B1b.4.3 Microorganisms and disease• a pathogen is a microorganism that causes disease• transmission of pathogens…
B1b.4.6 The third line of defence• specific immune system activated when first two lines of defence fail• white blood cells produce antibodies• antibodies fight pathogens…
• immunisation involves injecting a harmless amount of infection into body• specific immune system produces antibodies so is ready for a real attack
B1b.4.7 Types of drugs• Stimulants improve alertness and reaction times by increasing rate of diffusion across synapses, e.g. caffeine, amphetamine, cocaine. Addictive.• sedatives slow down the rate of diffusion across synapses, e.g. alcohol, barbiturates. Addictive and can cause tolerance [bigger doses needed].• painkillers [or analgesics], e.g. aspirin, paracetamol [Panadol™], ibuprofen, heroin, morphine. Block diffusion across synapses. Some are addictive.
B1b.4.8 Pain relief• overdose means taking more than stated amount of a drug• a paracetamol overdose can severely damage the liver• opiates [morphine and heroin] are addictive and create tolerance• tolerance can lead to an overdose• heroin is usually injected risking transmission of pathogens, e.g. HIV and hepatitis B• canabis can cause psychosis as well as bronchitis and lung cancer
B1b.4.9 Drug misuse and abuse• solvents are sedatives• solvent abuse can cause instant death by heart attack or suffocating if a plastic bag is used• solvents can damage the myelin sheath of neurones so that impulses are no longer carried• Alcohol is a sedative. Can be addictive and creates tolerance. Heavy drinking causes brain and liver damage.
B1b.4.10 Tobacco• tobacco has serious effects on breathing and circulatory systems• tobacco contains nicotine• nicotine is a very addictive stimulant• tabacco smoke contains carcinogens and carbon monoxide and causes emphysema• carbon monoxide binds to haemoglobin and reduces red blood cells ability to carry oxygen• nicotine and carbon monoxide together increase blood clotting that can cause a heart attack