9. Immunity

Question 1

Difference between active and passive immunity

Answer 1

Passive immunity is when antibodies are received from an outside source while active immunity is when antibodies can be produced within the person

Question 2

Explain active immunity

Answer 2

active immunity involved production of antibodies by a person in response to exposure to a particular antigen.
B memory cells and t cells are produced and react quickly if another encounter occurs with the same organism

Question 3

Natural active immunity

Answer 3

Acquired when a person comes into contact with a particular pathogen for the first time and activates the immune system to produce antibodies and b and t memory cells specific to that pathogens antigens

Question 4

Artificial active immunity

Answer 4

Results from vaccination. In this case the body is injected with either a disabled pathogen or its toxins

Question 5

Vaccines definition

Answer 5

Vaccines are used to activate the immune system to produce antibodies against specific disease causing organisms without actually causing the disease

Question 6

What is inside a vaccine?

Answer 6

VAccines are prepared using dead or attenuated pathogens so the antigens of the pathogen are still present thus triggering the immune response of the person injected with teh vaccine

Question 7

What does attenuated mean?

Answer 7

Organisms that are treated but not killed during the preparation of a vaccine are said to be attenuated, their disease causing capability had been removed and they can no longer replicate in human cells.

Question 8

Example of attenuating bacteria

Answer 8

A bacterium with a capsule causes disease
Remove capsule
Without its capsule the bacterium no longer causes disease but still acts as an antigen

Question 9

Types of vaccines

Answer 9

Living attenuated pathogens
Killed bacteria or inactivated viruses
One or more subunits of a pathogen
Treated harmless bacterial toxins, toxoids

Question 10

Which type of vaccine is strongest?

Answer 10

Killed or inactivated vaccines produce a weaker immune response compared to the response from using live attenuated vaccines and the immunity lasts for a shorter period.
Killed or inactivated vaccines have to be administered more than once.

Question 11

Difference between primary and secondary antibody response

Answer 11

When a vaccine is first injected into a person the immune system shows a primary antibody response.
A second injection of vaccine produces a secondary antibody response

Question 12

Herd immunity definition

Answer 12

Herd immunity is the indirect protection of populations from infection where that protection is created by the presence of immune individuals in the population and the protection is received by unvaccinated individuals

Question 13

When is herd immunity effective?

Answer 13

When a high proportion of the population has immunity

Applies only to infectious diseases

Question 14

Who does herd immunity protect?

Answer 14

The vulnerable, new born babies, elderly people and those with immunodeficiency diseases

Question 15

Passive immunity

Answer 15

Antibodies produced in one person (or other organism) and introduced into another can react with antigens to provide immunity.

Question 16

Advantage of passive immunity

Answer 16

Gives immediate protection to the person receiving the antibodies.
However the immunity is short lived as the person injected with the antibodies did not produce them therefore no memory cells were made

Question 17

Natural passive immunity

Answer 17

Occurs when a developing fetus receives maternal antibodies across the placenta which provides it with important protection IgG
A baby also acquired antibodies through the mothers breast milk iGG igA

Question 18

Artificial passive immunity

Answer 18

Occurs when a person is injected with antibodies
The antibodies are obtained from blood plasma collected from voluntary blood donors where the antibodies are extracted from the blood plasma
Or antibodies extracted from other organisms such as rabbits horses and rats

Question 19

Production of antivenom

Answer 19

1. Antivenene for a tiger snake bite can be produced by collecting antibodies from a rabbit injected with the antigen to this venom.
2. Inject antigen specific to tiger snake venom into rabbit
3. Rabbits B cells with specific antibody to venom antigen are activated. Many plasma cells produce and secrete large amounts of antibody into blood plasma.
4. Remove blood plasma from rabbit.
5. Antibodies extracted and purified from blood plasma.
6. Inject antibodies into person bitten by tiger snake. Antibodies neutralise venom.

Question 20

Autoimmune diseases

Answer 20

• Sometimes the ability of the immune system to recognise self material from non self material breaks down
• When this occurs the immune system reacts as if some of the body’s own cells are non self
• B cells produce antibodies and t cells attack and destroy self cells in the same way that they attack and destroy invading microorganisms
• Body produces autoantibodies which result in autoimmune disease

Question 21

Why do autoimmune diseases occur?

Answer 21

Infection with a pathogen displaying antigens similar to antigen molecules on the surface of a type of body cell results in the production of antibodies and activation of T cells which ultimately lead to the destruction of the pathogens. However body cells displaying the antigen on the cell membrane will also be targeted and destroyed.
Other factors such as hormones genes and drugs could trigger it

Question 22

Example of autoimmune diseases

Answer 22

Multiple sclerosis, type 1 diabetes. systemic lupus erthyematosus

Question 23

Allergy definition

Answer 23

An allergy is present when the persons immune system reacts abnormally to substances in the environment that are harmless to most people

Question 24

How does hypersensitivity occur

Answer 24

• B cell encounters the allergen and differentiates into plasma cells
• The plasma cell produces antibodies
  3. The antibodies bind to specific receptors on the surface of the mast cells
  4. The mast cell binds to the allergen when it encounters it again
  5. The mast cell releases histamine and other chemicals which together cause the symptoms of allergic reaction

Question 25

Immunodeficiency diseases

Answer 25

Immunodeficiency is a malfunction or deficiency in one or more components of the immune system.
Immune system fails to produce antibodies and the person lacks protection agaisnt pathogens

Question 26

Severe combined immunodeficiency SCID

Answer 26

Inherited disease, immune system fails to mature after birth. No thymus gland so T cells cannot be produced.

Question 27

Cancer

Answer 27

Cancer cells are normal cells that have undergone transformation, divide uncontrollably and possess tumour associated antigens that mark them as non self to the immune system. Can evade recognition by the immune system by shedding their associated antigens

Question 28

Monoclonal antibodies

Answer 28

• Drugs that can be used in the treatment of cancers

- Specifically designed sets of antibodies with every antibody in the set binding to the same antigen

Question 29

Difference between naked and conjugated antibodies

Answer 29

Naked monoclonal antibodies do not have any other molecules joined to them

• stop the growth of new blood vessels to cancer
• Signalling immune cells to attack cancers
• Blocking signals for cell division

COnjugated mca have additional groups attached

• Deliver anticancer drugs to cancer cells
• deliver radioisotopes to cancer cells