21st Century Science - B2 - Keeping Healthy

Harmful Micro-organisms reproduce quickly inside the body because it is warm, moist and they have a lot of food. These organisms damage cells  or make poisons that cause disease symptoms. However, the body has many barriers to stop these harmful cells from getting in such as your skin and the chemicals in tears. Also, the immune system is your main defense from these organisms, it defends against the damaging cellsand tries to destroy (ingest) them before they can cause illness. Your body then creates memory cells, which remember the bacteria/virus if and when they enter your body and defend against them before they can make you ill again.

Vaccines prevent you getting diseases. A vaccine contains dead or inactive parts of the disease-causing microorganism. Although the cells are dead, your body still makes anti-bodies against it which prevents you from getting the disease. You become immune. A high percentage of the population is vaccinated to prevent pandemics and epidemics. There are many strains of influenza (flu), because it mutates so quickly, new vaccines have to made all the time. However, some diseases such as HIV change too quickly so there is no vaccine for this. 

There isnt a vaccine for every dangerous microorganism, some make you ill before your immune system can destroy them. If the microorganism is bacteria or fungi then antibiotics can be taken to destroy them. There are problems with antibiotics though...

• Bacteria and Fungi can become resistant to some antibiotics
• You must only take them when necessary and finish the whole course. 

Mutations make an organism less affected by antibiotics. 
In most human trials on ill people, one group of patients takes the new drug, the other group are the controls, these people take the existing treatment or a placebo. A placebo looks like the new drug, but has no drugs in it. They are often not used in human trials because patients miss out on the benefits of both new and existing treatments. Human trials are either blind or double blind.
Blind = Doctors know who is is which group, patients don't.
Double Blind = Nobody knows who is in which group. 

The heart pumps blood around the body so heart muscle cells need a continuous supply of energy which comes from respiration. Respiration is a chemical reaction in cells.               glucose + oxygen ----> energy          Blood brings glucose and oxygen to the heart so that the blood needs it own blood supply.  Coronary arteries supply blood to the heart.  

Blood travels throughout the body through arteries and veins. Arteries carry blood away and veins bring blood towards the heart. Arteries have thick elastic, muscular walls and thin space for blood to flow through. Veins have a thin outer wall and a wide space for blood to flow through.     

Coronary arteries carry oxygenated blood towards the heart. Fat can build up in the artery walls, which a blood clot may form on. This then blocks the artery and stops oxygen from getting to the heart muscle. Heart cells die and the heart is permanently damaged = HEART ATTACK.

Poor diet, smoking, excess alcohol and stress increase the risk of heart attack.
It is more common in the UK than in NON-INDUSTRIALISED countries.