Flashcards in Cells And The Immune System Deck (63):
Why do some antigens generate an immune response?
The immune system identifies them as foreign
What do antigens allow the immune system to do?
To tell the difference between self cells and foreign invaders
Where are antigens usually found
On the surface of cells
Antigens that aren't normally found in the body are referred to as what?
What do antigens allow the immune system to identify?
Abnormal body cells
Cells from other individuals of the same species
What are pathogens??
Organisms that cause disease
Give examples of pathogens
How does the immune system know to destroy a pathogen
Because it has antigens on its surface which are identified as foreign by the immune system
What is the problem with organ transplants and blood transfusions within the immune system?
The cells are from another person therefore they have different antigens on their surface, therefore an immune response is triggered by the foreign antigens. This leads to the rejection of transplanted organs if drugs aren't taken
What is a phagocyte?
Type of white blood cell that carries out phagocytosis
What is phagocytosis
Engulfment of pathogens
Where are phagocytes found?
In the blood and in tissues
What are antigens?
Molecules that are usually proteins that trigger an immune response when detected by the body
Name the 4 main stages of the immune response
Outline the basic stages in phagocytosis
- phagocyte recognises the foreign antigens on the pathogen
- phagocyte engulfs the pathogen into its cytoplasm
- the pathogen is contained into a phagocystic vacuole
- lysosome fuses with the vacuole
- lysozymes in the lysosomes hydrolyise the pathogen
- the pathogen is destroyed and the phagocyte presents the pathogens antigens on its surface
Why does a phagocyte present the pathogens antigens on its surface when it's destroyed it and what does this mean it's acting as?
To activate other immune system cells
Acting as an antigen-presenting cell
What is another name for a T-cell
Phagocytes, T-Cells and B-cells are all types of what?
White blood cells
What do T-cells have on its surface?
What do the receptor proteins on T-cells bind to?
Complementary antigens presented to it by phagocytes
What do Helper T-cells do?
-Release chemical signals that activate and stimulate phagocytes and cytotoxic cells which kill abnormal and foreign cells
- also, they activate B-cells which secrete antibodies
What are B-cells covered in?
What are antibodies and what do they form?
They are proteins that bind to antigens to form an antigen-antibody complex
What are the differences between antibodies on different B-cells?
When are B-cells activated?
When an antibody on the surface of a B-cel binds to an antigen
When the substances from helper T-cells are released
What do the activated B-cells divide into
What do plasma cells secrete
Antibodies specific to the antigen
How many binding sites does an antibody have
An antibody having 2 binding sites means what?
It can bind to two pathogens at the same time, meaning pathogens become clumped together
What is the term for when pathogens are clumped together by antibodies
What kind of biological molecule are antibodies
What are the monomers of antibodies
The specificity of an antibody depends on what?
It's variable regions
What do the variable regions form on an antibody
Their binding sites
Each antibody has a variable region with a unique what??
What is the unique tertiary structure due to?
Different amino acid sequences
What do all antibodies have that is the same?
What is the function of helper T-cells?
Release chemical signals to activate phagocytes, cytotoxic T-cells and B-cells
What is the function of plasma cells?
What is the difference between the cellular and humoral immune response
Cellular immune response- involves T-cells and other immune cells that they interact with eg phagocytes
Humoral immune response- involves B cells, clinal selection and production of monoclonal antibodies
Give 4 differences between primary and secondary immune response
Primary is slow (speed)
Primary happens first time a pathogen invades
Primary involves B cells/ secondary also involves memory cells
There are symptoms with primary but not secondary
Why is the primary response slow
Because there aren't many b-cells that can make the antibody to bind to it
What do memory T-cells remember?
The specific antigen
What do memory B-cells remember
Record the specific antibodies needed to bind to the antigen
What is active immunity?
When your immune system makes its own antibodies after being stimulated by an antigen
What is natural active immunity
This is when you become immune after catching a disease
What is artificial active immunity
This is when you become immune after being given a vaccination containing a harmless dose of antigen
What is passive immunity?
When you are given antibodies made by a different organism
What is natural passive immunity
When a baby becomes immune due to antibodies it receives from its mother, through the placenta and boobie milk
What is artificial passive immunity
When you become immune after being injected antibodies from someone else
Name 4 differences between active immunity and passive immunity
Requires exposure to antigen Don't require exposure
Memory cells are produced Memory cells aren't produced
Takes a while for protection to Protection is immediate
Protection is long term Protection is short term because
antibodies are broken down
What do vaccines contain
Antigens that are free or attached to the dead/ attenuated (weakened) pathogen
What are the two ways that vaccines can be given
Orally or injected
Give 2 disadvantages of taking a vaccine orally
-They may be broken down my enzymes in the gut
-The molecules of the vaccine may be too large to be absorbed into the blood
Why are booster vaccines sometimes given later on
To make sure more memory cells are produced
What is antigenic variation
When the antigens on the surface of a pathogen change
Explain why you can become ill with the flu even if you've been infected with the influenza virus before
Because if the pathogen undergoes antigenic variation, memory cells produced from the first infection won't recognise the antigens from the new strain. The immune system has to carry out a primary response to the new antigens and as this takes time to get rid of the infection, you get ill again
In antigenic variation how are different antigens formed on a pathogen?
Due to changes in the gene of a pathogen
How often does the influenza vaccine change?
What is the influenza virus otherwise known as
What are monoclonal antibodies
Antibodies produced from plasma cells
What are plasma cells
Genetically identical B cells