Preventing And Treating Disease Flashcards
What’s a non communicable disease
Non-communicable diseases cannot be passed from one person to another. They include heart disease, most types of cancer and many diseases of the nervous, endocrine and digestive systems. Communicable diseases are caused by pathogens and can be passed from person to person.
When you come into contact with a foreign antigen, you need some form of immunity to prevent you getting the disease. There are several ways of achieving this immunity.
Natural immunity
Some forms of immunity occur natural in the body:
-when you meet a pathogen for the first time, your immune system is activated and antibodies are formed, which result in the destruction of the antigen. The immune system produces T and B memory cells so if you meet a pathogen for a second time, your immune system recognises the antigens and can immediately destroy the pathogen, before it causes disease symptom. This is known as active because the body has itself acted to produce antibodies and/or memory cells.
-The immune system of a new-born baby is not mature and it cannot make antibodies for the first couple of months. A system has evolved to protect the baby for those first few months of life. Some antibodies cross the placenta from the mother to her fetus while the baby is in the uterus, so it has some immunity to disease at birth. The first milk a mammalian mother makes is called colostrum, which is very high in antibodies. The infant gut allows these glycoproteins to pass into the bloodstream without being digested. So within a few days of birth, a breast-fed baby will have the same level of antibody protection against disease as the mother. This is natural passive immunity and it lasts until the immune system of the baby begins to make its own antibodies. The antibodies the baby receives from the mother are likely to be relevant to pathogens in its environment, where the mother acquired them.
Artificial immunity
Some diseases can kill people before their immune system makes the antibodies they need. Medical science can give us immunity to some of these life-threatening diseases without any contact with live pathogens.
Artificial passive immunity
For certain potentially fatal diseases, antibodies are formed in one individual (often animal), extracted and then injected into the bloodstream of another individual. This artificial passive immunity gives temporary immunity-it doesn’t last long but it can be lifesaving.
Artificial active immunity-the principles of vaccination
In artificial active immunity the immune system of the body is stimulated to make its own antibodies to a safe form of an antigen (a vaccine) which is injected into the bloodstream (vaccination). The antigen is not usually the normal live pathogen, as this could cause the disease and have fatal results.
Steps of vaccination
1) The pathogen is made safe in one of a number of ways so that the antigens are intact but there is no risk of infection. Vaccines may contain:
-killed or inactivated bacteria and viruses
-attenuated (weakened) strains of live bacteria or viruses
-toxins molecules that have been altered and detoxified
-isolated antigens extracted from the pathogen
-genetically engineered antigens
2) Small amounts of the safe antigen, known as the vaccine, are injected into the blood
3) The primary immune response is triggered by the foreign antigens and your body produces antibodies and memory cells as if you were infected with a live pathogen.
4) If you come into contact with a live pathogen, the secondary immune response is triggered and you destroy the pathogen rapidly before you suffer symptoms of the disease.
The artificial active immunity provided by the vaccines may last a year, a few years or a lifetime. Sometimes boosters (repeat vaccinations) are needed to increase the time you are immune to a disease.
Vaccines and the prevention of epidemics
Vaccines are used to give long-term immunity to many diseases. However they are also used to help prevent epidemics. An epidemic is when a communicable disease spreads rapidly to a lot of people at a local or national level. A pandemic is when the same disease spreads rapidly across a number of countries and continents.
At the beginning of an epidemic, mass vaccination can prevent the spread of the pathogen into the wider population. When vaccines are being deployed to prevent epidemics, they often have to be changed regularly to remain effective.
When a significant number of people in the population have been vaccinated, this gives protection to those who do not have immunity. This is known as herd immunity, as there is minimal opportunity for an outbreak to occur.
Communicable diseases that cause problems at a global level cannot yet be prevented by vaccination. Examples:
-malaria-plasmodium, the protoctists that causes malaria. It is very erasive- it spends time inside the erythrocytes so it is protected by self antigens from the immune system, and within an infected individual its antigens reshuffle.
-HIV, the human immunodeficiency virus that causes AIDS. It enters the macrophages and T helper cells, so it has disabled the immune system itself.
So far scientists have been unable to develop a vaccine for these diseases, which between them affect millions of people globally every year.
Medicines and management of disease
Medicines can be used to treat communicable and non-communicable diseases. Medicines can be used to treat symptoms and cure them, making people feel better. Common medicines include painkillers, anti-inflammatory and anti-acid medicines (which reduce indigestion)
Medicines that cure people include chemotherapy against some cancers, antibiotics that kill bacteria, and Antifungals that kill fungal pathogens.
Sources of medicines
-penicillin- its source is commercial extraction originally from mould growing on melons.- it is an antibiotic, the first effective treatment against many common bacterial diseases.
-paclitaxel-derived originally from yellow trees and treats breast cancer
-aspirin- based on compounds from willow bark-painkiller, anti-coagulant, anti-pyretic (reduces fever) and anti-inflammatory
-vancomycin-derived from soil fungus- one of our most powerful antibiotics
Biodiversity
In the 21st century biodiversity is rapidly being lost around the world m, including the destruction of rain forests, the loss of coral reefs and loss of habitat for natural ecosystems in countries all around the world. This is at least partly due to human activities. Scientists have not yet explored and identified and analysed a fraction of life on earth. One of many reasons why it is so important to maintain biodiversity is to make sure we do not destroy a plant, animal or microorganism which could give us the key to a life-saving drug.
Pharmacogenetics-drug design for the future
Personalised medicine-a combination of drugs that work with your individual combination of genetics and disease- is the direction in which medicine is going. The human genome can be analysed relatively rapidly and cheaply, giving a growing understanding of the genetic basis of many diseases. In future, this type of treatment, where clinicians looks at the genome of their patients and the genome of the invading pathogen before deciding how to treat them, will become increasingly common.
