B6 - Preventing And Treating Disease (Y10 - Spring 2) Flashcards
🟢 How do Antigens and White Blood Cells Work
Every cell has unique proteins on it’s surface called antigens on the microorganisms that get into your body are different to the ones on your own cells. Your immune system recognises that they are different.
Your white blood cells then make specific antibodies, which join up with the antigens and inactivate or destroy that particular pathogen.
Some of your white blood cells (the memory cells) rememeber the right antibod needed to destroy a particular pathogen. If you meet tnat pathigen again, these memory cells can make that same antibody very quickly to kill the pathogen, so you become immune to the disease.
The first time you meet a new pathogen you get ill because there ie a delay while your body sorts out the right antibody neded. The next time, your immune system destroys the invaders they can make you feel unwell.
🟢 What are Vaccines and How Do They Work
You can be protected against many of these serious diseases by the vaccination (also known as immunisation).
Immunisation involves giving you a vaccine made of a dead or inactivated form of a disease causing microorganism. It stimulates your body’s natural immune response to invading pathogen.
A small amount of dead or inactive forms of a pathogen is introduced into your body. This sitimulates the white blood cell to produce the antibodies needed to fight the pathogen and prevent you from getting ill. Then, if you meet the same, live pathogen, your white blood cells can respond rapidly. They can make the right antibodies just as if you had already had the diease, so that you are protected against it.
Doctors use vaccines to protect us both against bacterial diseases, such as tetaus and diphthetia, and viral diseases such as pilio, measles and mumps. For example, the MMR vaccine protects aginst measles, mumps, and rubella. Binccines have saved millions of lives around the world. One disease - smallpox - has been completely wiped out by vaccinations. Doctors hope polio will also disappear in the next year.
🟢 What is Herd Immunity and how does it Work
If a large proportion of the population is immune to a disease, the spread of the pathogen is the populatiom is very much reduced and the disease may even disappear. This is known as herd immunity. If, for any reason, the number of people taking up a vaccine fall, the herd immunity is lost and the disease can reappear. This is what happened in the UK in the 1970’s when there was a scare about the safety of the whooping cough vaccine. Vaccination rates fell from over 80% to around 30%. In the following years, thousands of children got whooping cough again and a substantial number died. Yet the vaccine was as safe as any medicine. Eventually people realised this and enough children were vaccinated for herd immunity to be effective again. There are gloabl vaccination programmes to control a number diseases, including tetanus in mothers and new-born babies, polio, and measles. The World Health Organisation want 95% children to have two doses of measles vaccine to give global herd immunity. Current global figures show that 85% of children get the first dose and 56% get the second. It will take money and determination to get global herd immunity against a range ofdifferent diseases, but advantages both to individuals and to global economies are huge.
🟢 How Vaccination protects you against dangerous infectious diseases
Firstly, small amounts of dead or inactive pathogen are put into your body, often by injection.
Then, the antigens in the vaccines stimulate your white blood cells into making antibodies. The antibodies destroy the antigens without any risk of you getting the disease.
You are immune to future infections by the pathogen. That’s because your body can respond rapidly and make the correct antibody as if you had already had the disease. Also, in future infections a lot more antibodies will be created in a lot quicker period of time.
🟢 What happens when a B-Cell is 1st Infected, and when it’s secondly infected
B-Cell upon 1st Infection:
- The B-Cell will bind to the specific antigen on the surface.
- This means that masses of antibodies will be produced, which will go on to eliminate the infection.
- After this, memory B-Cells are formed and circulate around the body. This will alow the antibodies to produce quicker in future.
B-Cell upon 2nd Infection:
-The memory B-Cells will divide into antibodies quicker than the first time and will eliminate the pathogen faster.
❌ How can Painkillers help, but what are their limitations too?
Drugs such as asprin and paracetomol are very useful painkillers. When you have a cold, they will help relive your headache and sore throat. On the other hand, they will have no effect on the viruses that have entered your tissues and that have made your feel ill. Many of the medicines you can buy at chemists or a supermarket relieve your symptoms but do not kill the pathogens, so they do not cure you any faster. You have to wait for your immune system to overcome the pathogens before you actually get well again.
❌ What are Antibiotics
Drugs that make you feel better are useful, but in some cases what you really need are drugs that can cure you. You can use antiseptics and disinfectants to kill bacteria outside of your body, but they are far too poisonous to use inside your body. They will kill you, along with the pathogens at the same time.
The drugs that have really changed the treatment of communicable diseases are antibiotics. These are medicines that can work inside your body to kill bacterial pathogens. The impact of antibiotics on deaths from communicable diseases have been enormous.
❌ How Do Antibiotics Work
Antibiotics, such as penicillin, work by killing the bacteria that cause disease whilsit they are inside your body. They damage the bacterial cells without harming your own cells. Bacterial diseases that killed millions of people in the past can now be cured using antibiotics. They have had an enormous effect on our society.
If you need antibiotics, you usually take a pill, or syrup, but if you are very ill antibiotics may be put straight into your bloodstream. This makes sure that they reach the pathogens in your cells as quickly as possible. Some antibiotics kill a wide range of bacteria. Others are very specific and only work against particular bacteria. It is importamt that the right antibiotic is chosen and used. Specific bacteria be treated with the specifc antibiotic that is effective against them.
❌ Why/How do Bacteria become Antibiotic Resistant
The antibiotics become resistant overtime, after the bacteria evolve over the years. This means that certain antibiotics are changing faster than new antibiotics are able to be created. This can lead to certain ‘superbugs’ that cannot be treated by antibiotics, as the bacteria that has made the ‘superbug’ has resistance.
Bacteria can randomly mutate at times, but can sometimes lead to their characteristics being changed before it forms a new colony of resistant bacteria. This process can happen again and again with different types of antibiotics, leading one type of bacteria being resistant to very many different types of antibiotics. Around 1,000 tonnes of bacteria are given out per year, but 2/3 of this is given to animals to try to make them stay strong and healthy, even if they are not unwell. This creates a breeding ground for bacteria to become immune to lots of different types of antibiotics.
It is very important that you finish your course of antibiotics even when you feel better, to make sure that all of the bacteria is killed off, meaning there are no left over bacterias when can evolve and become resistant.
❌ What’s leading more Bacteria to become Antibiotic Resistant?
Unfortunately, antibiotics are not the complete answer to the problem of infectious diseases:
- Antibodies cannot kill viral pathogens so they have no effect on diseases caused by viruses. Viruses reproduce inside the cells of your body. It is extremely difficult to develop drugs that will kill the viruses without damaging the cells and tissues of your body at the same time.
- Strains of bacteria that are resistant to antibiotics are evolving. This means that antibiotics which used to kill a particular type of bacteria no longer have an effect, so they cannot cure the disease. There are some types of bacteria that are resistant to all known antibiotics. The emergence of antibiotic strains is a matter of great concern. Unless scientists can discover new antibiotics soon, we may no longer be able to cure bacterial diseases. This means that many millions of people in the future will die of bacterial diseases that we can currently cure.
🟠 How Do You Reduce the Rate of Bacteria becoming Antibiotic Resistant?
Bacteria can eveolve rapidly because they reproduce at a fast rate. Mutations of bacterial pathogens produce new strains. Some strains might be resistant to antibiotics, and so are not killed. They survive and reproduce, so the population of the resistant strain rises. The resistant strain will then spread because people are not immune to it and there is no effective treatment.
To reduce the rate of development of antibiotic resistant strains (like MRSA):
- Doctors should not prescribe antibiotic inappropriately, such as treating non-serious or vial infections
- Patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and form resistant strains
- The agricultural use of antibiotics should be restricted
The development of new antibotics is costly and slow. It is unlikely to keep up with the emergence of new resistant strain.
❌ Where Do Drugs Come From?
Traditionally, drugs were extracted from plants or microorganisms such as moulds. In ancient Egypt, mouldy bread was used on septic wounds. Other examples include the heart drug digitalis (comes from foxgloves), the painkiller asprin (comes from willow), and penicillin (which was discovered by Alexander Flemming from the Penicillium mould).
However nowadays, scientists often adapt chemicals from microorganisms, plants, and animals to make more effective drugs. Most new drugs are synthesised by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant.
❌ How did Flemming Discover Penicillin?
In 1928, while studying influenza, Fleming noticed that mould had developed accidentally on a set of culture dishes being used to grow a certain type of germ he was testing on (staphylococci germ). The mould had created a bacteria-free circle around itself. Fleming experimented further and named the active substance penicillin.
❌ What Needs To Happen For A New Medical Drug To Be Released?
New Medicinal drugs have to be tested and trialled before being used to check tnat they are safe and effective.
New drugs are extensively tested for toxicity, efficacy and dose.
Preclinical testing is done in a laboratory using cells, tissues and live animals. Clinical trials use healthy volunteers and patients. In clinical trials:
- Very low doses of the drug are given at the start of the clinical trial
- If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug
- In double blond trials, some patients are given a placebo.
❌ What Drugs Originate From Plants
There are a number of drugs used today that are based on traditional medicines extracted from plants. Digitalis is one of several drugs extracted from foxgloves, and the drug digoxin is another. They have been used since the 18th century to help strengthen the heartbeat. There are many more modern drugs, but doctors still use digoxin, especially for older patients with heart problems. Large amounts of these chemicals can instead act as poisons.
The painkiller aspirin originates from a compound found in the bark of willow trees. The anti-inflammatory and pain-relieving properties were first recorded in 400BC. In 1897, Felix Hoffman synthesised acetyl salicylic acid (aspirin) which not only relieves pain and inflammation better than willow bark, but has fewer side affects. Aspirin is still commonly used to treat a wide range of health problems.
