Unit 3.2.6 - The Bodies Defense System Flashcards Preview

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Flashcards in Unit 3.2.6 - The Bodies Defense System Deck (41)
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What on pathogens trigger an immune response?

The foreign antigens on its surface


What is an antigen?

A large complex molecule that triggers an immune response - like a glycoprotein


What is an antibody?

A protein secreted by B cells in response to a non-self antigen


Describe the structure of an antibody?

Four polypeptide chains joined together by disulphide bond, two of the chains are long heavy longs and two of the chains are short lighter chains.


What is the same about all antibodies?

The constant region


What is different between all antibodies?

The variable region


What is the shape of the variable region determined by?

The sequence of amino acids which make up the primary structure of the protein


Draw the structure of an antibody?

See flash card 21


What type of white blood cell carries out phagocytosis?

A phagocyte


What are the five steps in phagocytosis?

1.) The phagocyte recognises the foreign antigens on the pathogen
2.) It moves its cytoplasm around the pathogen engulfing it in a phagosome
3.) A lysosome fuses with the phagosome
4.) It releases lysosomal enzymes
5.) These enzymes begin to break down the pathogen


What is the pathogen contained in during phagocytosis?

A phagosome


How do phagocytes activate T cells?

After phagocytosis they present the foreign antigens on their surface which activates the T cells


Name two other types of white blood cells, not including phagocytes?

B cells and T cells


What type of response do the T cells form?

The cellular response


What type of response do the B cells form?

The humoral response


What cells form the cellular response?

T cells


What forms the humoral response?

B cells and the production of antibodies


What are the two types of T cells?

Killer and helper cells


What do the killer T cells do?

They attach to antigens on the pathogen and kill the cell


What do helper T cells do?

They activate the B cells


How do B cells becomes activated?

They have antibodies on their surface, when they bind with foreign antigens they form antigen-antibody complexes and so become activated


When the B cells become activated what cells do they produce and how?

They divide by mitosis, so that the new cells are genetically identical and have the same antibodies which are specific to the antigens on the pathogen, these are called plasma cells


What three ways do antibodies help the immune response?

1.) coating the pathogen to make it easier for the phagocyte to engulf
2.) coating the pathogen to prevent it from entering host cells
3.) bind to and neutralise toxins produced by the pathogens


What do both B and T cells produce which mean you become immune to a pathogen after coming in contact with it?

Memory cells


Why do memory cells mean you are immune to a pathogen?

If you ever come in to contact with the same antigen again they recognise it and produce plasma cells much faster than before so you don't get ill and so you are immune


What type of response are plasma cells known as?

Primary response


What type of response are memory cells known as?

Secondary response


If the primary or secondary response slower and why?

Primary because there aren't many B cells making the correct antibody so they have to divide which all takes time


Why are you usually given a second injection?

To boost the number of memory cells in your blood so that you can still quickly produce plasma cells to fight of the pathogen


What is meant by antigenic variation?

When pathogens can change their antigens on their surface