Unit 1 -Disease And Immunity

Front 1

What is a pathogen?

Back 1

A pathogen is any organism that causes disease. Pathogenic microorganisms include bacteria, fungi and viruses.

Front 2

How do pathogens penetrate the body?

Back 2

Pathogens penetrate the body through:

1) Gas-exchange system

2) Skin

3) Digestive system

Front 3

How do pathogens cause disease?

Back 3

1) The production of toxins

2) Cell damage by rupturing them to release nutrients inside, breaking down nutrients inside the cell for their own use or by replicating inside the cells and bursting them when they're released.

Front 4

What happens during phagocytosis?

Back 4

1) A phagocyte recognises the antigen on a pathogen.

2)The cytoplasm of the phagocyte moves towards to pathogen, being attracted by chemo-attractants.

3) The phagocyte then engulfs the pathogen and then the pathogen is contained in a phagocytic vacuole in the cytoplasm of the phagocyte.

4) Then a lysosome (containing lytic enzymes) fuses with the vacuole and the lytic enzymes break down the pathogen.

Front 5

What types of immune response are there?

Back 5

1) Cellular-mediated response - The T-cells and other immune system cells that they interact with.

2) Humoral - b-cells and the production of antibodies from the humoral response.

Front 6

How do plasma cells make more antibodies specific to an antigen?

Back 6

Plasma cells are identical to the B-cell. They secrete many of the same antibodies to the antigen. Antibody functions include:

1) Coating the pathogen to make it easier for the phagocyte to engulf it.

2) Coating the pathogen to prevent it from entering the host cell.

3) Binding to and neutralising toxins produced by the pathogen.

Front 7

What are antibodies?

Back 7

Antibodies are proteins. The specificity of an antibody depends on the variable regions. Each antibody has a different shaped variable region. That's complementary to one specific antigen. The constant regions are the same in all antibodies.

Front 8

What is the primary immune response?

Back 8

1) Occurs when an antigen enters the body for a first time.

2) The primary response is slow because there aren't many b-cells that can make the anti-body needed to bind to it.

3) Eventually the body will produce enough of the right antibody to overcome the infection.

4) After being exposed to the infection, the B-cells and T-cells produce memory cells. Memory T-cells remember the specific antigen. Memory B-cells record the specific antibodies needed to bind to the antigen.

Front 9

What is the secondary immune response?

Back 9

1) If the same pathogen invaded the body again, the immune response would be quicker and stronger.

2) Memory B-cells divide into plasma cells that produce the right antibody to the antigen. Memory T-cells divide into the correct type of T-cells to kill the cell carrying the antigen.

3) The secondary response will often overcome the pathogen before any signs of symptoms show.

Front 10

How to vaccines protect individuals and populations against disease?

Back 10

1) Vaccines contain antigens that cause your body to produce memory cells against a particular pathogen without the pathogen causing disease. The pathogen, which is injected or orally taken, is usually a dead or weakened version. This means that you'll become immune and not develop any symptoms.

2) The disadvantages of taking a vaccine orally is that it could be broken down by enzymes in the gut or the molecules of the vaccine may be too large to be absorbed into the blood.

Front 11

What is antigenic variation?

Back 11

1) Antigenic variation is the altering of the tertiary structure of the surface antigen on the pathogen.

2) If you're infected for a second time, the memory cells from the primary response wont recognise the different antigens.

3) Antigenic variation makes it difficult to develop vaccines against some pathogens for the same reason. Examples of pathogens that show antigenic variation are HIV and the influenza virus.

Front 12

What are monoclonal antibodies?

Back 12

1) Monoclonal antibodies are antibodies produced from a single group of identical B-cells (plasma cells).

2) Antibodies are very specific because their binding sites have a unique structure that only one particular antigen will fit into a binding site with a complementary shape.

3) Polyclonal antibodies are produced from different B-cells, so they variable region.