Section 5 biology

• Communicable diseases are diseases that can be spread between people.
• Non-communicable diseases are diseases that cannot be spread between people. e.g. Cancer
• Pathogens are organisms that cause communicable diseases. Pathogens include viruses, bacteria, fungi and protists.
• The communicable diseases: Cholera- a bacteria, spreads through water. Tuberculosis- a bacteria, spreads through coughing or sneezing. Malaria- a protist, spreads through mosquitos. Chalara ash dieback- a fungus, spreads through the wind.
• STI's are sexually transmitted diseases that can be spread through having sex.
• HIV is a sexually transmitted virus, viruses aren't cells. This means they infect living cells in order to reproduce.
• HIV is the human immunodeficiency virus and it infects and kills white blood cells.
• AIDs is a condition where the immune system becomes very weak and eventually stops working which means they are more likely to get a communicable disease.
• HIV is spread through infected bodily fluids. Like blood, semen and vaginal fluids. One of the main ways to prevent it is by using a condom.
• Chlamydia is a bacteria and can result in infertility. The spread of chlamydia can be reduced by: Wearing a condom, avoiding sexual contact and screening people.
• Physical barriers stopping disease: Skin- stops pathogens getting inside you and if it gets damaged your blood forms sticky clots which seals cuts and keeps pathogens out.
• Physical barriers stopping diseases: Mucus and cilia- Mucus catches dust and pathogens before they reach the lungs. The cilia push the gunk filled mucus up to the back of the throat where it can be swallowed.
• Chemical barriers stopping diseases: Eyes- Produce a chemical barrier called lysozyme which kills bacteria on the surface of the eye.
• Chemical barriers stopping disease: Stomach- Produces hydrochloric acid which kills most pathogens that are swallowed.
• If pathogens get into your body your immune system kicks in to destroy them. White blood cells are the most important part of the immune system.
• the body produces antibodies when fighting off a new pathogen.
• Memory lymphocytes make someone immune to a pathogen. it will remember a specific antigen and if the same pathogen enters the body again it will recognise its antigens and the immune system can respond quickly.
• Immunisation can you stop you from getting infections. It usually involves injecting a dead or inactive pathogen into the body. The pathogens have antigens so your body makes antibodies for it. So if you get infected with a certain infection again your body will be able to fight it off quicker.
• Antibiotics stop processes in bacteria cells. e.g. stop cells from being built. They don't stop processes in the cells of the host organism. So antibiotics kill bacteria cells but not the host cells. Antibiotics don't destroy viruses.
• Development of new drugs: A drug has to be discovered and once a possible drug has been discovered it needs to be developed.
• clinical testing: Drugs are first tested on human cells and tissues in the lab. Next the drugs are tested on live animals. If the drug works they need to figure out how toxic it is and the dose at which it works best.
• If drugs pass the animal testing they get tested on humans. First it's tested on healthy people to make sure that it doesn't have any harmful side effects when the body is working normally. Then if its successful the drugs can be tested on ill people.
• Anything that increases a persons chance of getting a disease is called a risk factor. Risk factors for a disease can be things a person cant change. e.g. Their age. But can also be lifestyle factors a person can change.
• Risk factors a person can change include: Smoking, this can increase the risk of developing cardiovascular disease. Because nicotine in cigarettes increases heart rate and blood pressure which is what causes the disease. Diet and exercise, a diet with too many or too little nutrients can lead to malnutrition which can cause different health problems. And having a diet high in sugar, salt and fat can cause obesity. And alcohol, too much increases the risk of liver disease because the liver breaks down alcohol.
• Non-communicable diseases can have wide ranging effects: e.g. In areas where there are high levels of smoking, there is likely to be a lot of cardiovascular disease which puts pressure on hospitals. People with non-communicable diseases might not be able to work which can effect the country's economy and it also costs a lot of money to treat people with non-communicable diseases. Cardiovascular disease is the number one cause of deaths in the world.
• Body mass index (BMI) is used to as a guide to help decide whether someone is underweight, normal, overweight or obese. It's calculated from their height and mass, the formula is: BMI= mass (kg) divided by Height (m) squared.
• A waist to hip ratio can also be used to measure someone's weight. The formula is: Waist-to-hip ratio= waist circumference divided by hip circumference.
• Abdominal obesity is where you have to much weight around your tummy, A person with abdominal obesity has a bigger risk of developing health problems e.g. type 2 diabetes.
• too much cholesterol in the blood can cause fatty build up in the arteries which reduces blood flow. Blood vessels can be damaged and the damage can cause blood clots to form which can block blood flow completely. If blood flow to the heart muscle is blocked it can cause a heart attack, and if blood flow to the brain is blocked it can cause a stroke.
• People with cardiovascular disease are encouraged to eat a healthy balanced diet, it should be low in saturated fats. as well as to exercise regularly and stop smoking. Lifestyle changes are often recommended before any other treatments because it doesn't have any downsides to it.
• Some people need to take medicines to treat cardiovascular disease for the rest of their lives. E.g. Statins reduce the amount of cholesterol in the bloodstream. Anticoagulants make blood clots less likely to form. Antihypertensives reduce blood pressure. All these medicines have negative side effects e.g. Antihypertensives can cause fainting.
• Surgery can be needed to treat cardiovascular disease for example: Put in stents which are tubes inserted inside arteries which keep them open and let blood flow to the heart muscles. Coronary bypass surgery which is where a healthy blood vessel is put into the heart which lets blood flow around a blocked artery. And a heart transplant.
• Surgery is very risky, for example you could get an infection or lose a lot of blood.