Preventing and treating disease

Question 1

What is the primary immune response?

Answer 1

When a pathogen enters the body for the first time, the antigens on its surface activate the immune system

Question 2

Why is the primary immune response so slow?

Answer 2

-there are not many T lymphocytes clones which are complementary in shape to the antigen so clonal selection takes longer. Also there aren’t many B lymphocyte clones which are complementary in shape to the antigen so antibody- making capacity is small until clonal expansion has taken place. = person is ill with symptoms of the disease

Question 3

What is a secondary immune response?

Answer 3

When the T and B cells produce memory cells after being exposed to an antigen, which give the person immunity from that specific pathogen if it infects the person for a second time. It often gets rid of the pathogen before the person shows any of the symptoms

Question 4

Explain what effect T and B memory cells have due to having a limited lifespan.

Answer 4

• won’t be immune to a particular pathogen forever

- this means once all the T and B memory cells have died, the person may be susceptible to attack by the pathogen again.

Question 5

What is the purpose of having booster vaccines?

Answer 5

-being continually exposed to the pathogen means you will continue to make the T and B memory cells, therefore remain immune

Question 6

Compare the primary immune response with the secondary immune response in terms of entrance of pathogen, speed of response, cells activated, and whether there are symptoms

Answer 6

Primary:

• pathogen enters for the first time
• speed of response is slow
• cells activated are T and B lymphocytes
• there are symptoms

Secondary:

• pathogen enters for a second time
• speed of response is fast
• cells activated are T and B memory cells
• no symptoms

Question 7

What are the 4 types of immunity?

Answer 7

1. Natural active immunity
2. Natural passive immunity
3. Artificial active immunity
4. Artificial passive immunity

Question 8

What is natural active immunity?

Answer 8

• when the pathogen invades the body and a primary immune response is mounted against it
• person has the symptoms of the disease and becomes ill
• survivors of the infection have T and B memory cells high are able to mount a secondary response against the same pathogen in the future

Question 9

What is natural passive immunity?

Answer 9

• newborn babies are protected from pathogens because their mothers antibodies are passed through the placenta and colostrum (breast milk produced in the first few days of infant life)
• if mother passes antibodies for a particular antigen, and this pathogen invades the baby’s body, the baby will have no symptoms and not be ill
• there will be no immunological memory for this pathogen however as the baby has not made the antibodies through clonal selection and clonal expansion
• once maternal antibodies have disappeared the baby will no longer have immunity

Question 10

What is artificial active immunity?

Answer 10

• prevents epidemics of dangerous communicable diseases through vaccinations, a harmless version of the pathogen/ foreign antigen is introduced into the body
• a primary immune response is triggered (clonal selection and clonal expansion) but patient doesn’t become ill as the pathogen is dead or weaker so is harmless
• memory T and B cells are made so if this pathogen enters in the future, the secondary response will be mounted

Question 11

What is the artificial passive immunity?

Answer 11

• if a dangerous pathogen invades the body there’s a risk the patient may die before they make the antibodies to deal with the pathogen
• an emergency treatment is to inject the patient with the antibodies against the pathogen
• no T or B memory cells are made so there’s no immunological memory for this pathogen in the future

Question 12

What is an epidemic?

Answer 12

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

Question 13

What is a pandemic?

Answer 13

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

Question 14

What is an endemic?

Answer 14

Where a communicable disease is always present in an area. E.g Malaria is endemic in parts of Africa

Question 15

What can help stop the spread of a pathogen at the beginning of an epidemic and why?

Answer 15

• quarantine
• mass vaccination = when a significant number of people have been vaccinated there is a reduced reservoir of potential hosts for the pathogen therefore the epidemic is less likely to be passed on

Question 16

Explain what is meant by herd immunity

Answer 16

• where a high proportion of the population have been vaccinated and this gives protection to those who can’t be vaccinated
• with most individuals immune, there is minimal opportunity for an out peak to occur