Preventing & Treating Disease

Question 1

Natural active immunity

Answer 1

• when you meet a pathogen for the first time your immune system is activated and antibodies are formed which results in the destruction of the antigen
• the immune system produces T and B memory cells so if you meet a pathogen for the second time your immune system recognised the antigens and can immediately destroy the pathogen before it causes disease symptoms
  = natural active immunity
• known as natural active immunity because the body has itself acted to produce antibodies and/or memory cells

Question 2

Natural passive immunity

Answer 2

• immune system of a new born baby is not mature and it cannot make antibodies for the first couple of months
• system has evolved to protect the baby for those first few months of life
• some antibodies cross the placenta from the mother to her foetus while the baby is in the uterus so it has some immunity to disease at birth
• colostrum which is very high in antibodies
• infant gut allows these glycoproteins to pass into the blood stream without being digested
• within a few days of birth a breast-fed baby will have the same level of antibody production against disease as the mother
• this is natural passive immunity and it lasts until the immune system of the abbot 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

Question 3

Colostrum

Answer 3

First milk a mammalian mother makes

Question 4

Artificial passive immunity

Answer 4

• for certain potentially fatal diseases antibodies are formed in one individual, extracted and then injected into the bloodstream of another individual
• this is artificial passive immunity- gives temporary immunity, it doesn’t last long but can be life saving

Question 5

Artificial active immunity

Answer 5

• the immune system of the body is stimulated to make its own antibodies to a safe form of an antigen which is injected into the bloodstream
• antigen is not usually the normal live pathogen as this could cause the disease and have fatal results

Question 6

Vaccines may contain :

Answer 6

• killed or inactive bacteria and viruses for eg. Whooping cough
• attenuated strains of live bacteria or viruses for eg. Rubella
• toxin molecules that have been altered and detoxified for eg. Tetanus
• isolated antigens extracted from the pathogen for eg. Influenza vaccine
• genetically engineered antigens for eg. Hepatitis B

Question 7

Outline the steps of vaccination

Answer 7

1. Small amounts of the safe antigen known as the vaccine are injected into the blood
2. 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
3. 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

Question 8

Epidemic

Answer 8

When a communicable disease spreads rapidly to a lot of people at a local or national level

Question 9

Pandemic

Answer 9

When the same disease spreads rapidly across a number of countries and continents

Question 10

Mass vaccination

Answer 10

• 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

Question 11

Herd immunity

Answer 11

When a significant number of people in the population have been vaccinated this gives protection to those who do not have immunity

There is minimal opportunity for an outbreak to occur