3.2.4 Cell Recognition And Immune System Flashcards
What are the 2 types of defence?
Non- specific:
Response is immediate and same for all pathogens
Examples- physical barriers(skin), phagocytosis
Specific :
Response is slower and specific for each pathogen
Examples- cell meditated cells(T lymphocytes), humoral response(B lymphocytes)
Differences in non-specific to specific response?
Specific targets specific pathogens and is slower (T+B lymphocytes)
What is a self antigen?
Antigen on your own cells
What is an antigen?
Any party of an organism or substance that is recognised as non-self(foreign) by the immune system and stimulates the immune system
What are molecules that would trigger an immune responses?
Pathogen(HIV)
Non-self material(protein on foreign cell)
Cancerous cell antigens
Toxins
Explain phagocytosis
Phagocyte move towards pathogen (it’s attracted to the pathogens chemicals)
Phagocyte recognises the antigens on the pathogen and binds to it
Phagocyte engulfs pathogen in a phagocytic vesicle
Lysosome(containing lysozyme) fuses with pathogen vesicle. Pathogen is hydrolysed
Phagocyte presents the pathogens antigens to active other immune cells
(Becomes an APC - antigen presenting cell)
Differences between Band T lymphocytes?
B lymphocytes mature in the bone marrow and are part of the humoral response which produces antibodies
T lymphocytes mature in the thymus glands and are part of cell mediated response
What does a helper T cell do after finding an APC?
A helper T cell with compliments shaped receptors bind to the antigen
The helper T cell is activated and divides by mitosis
After a T cell divides what happens?
Some develop into memory T cells
Some stimulate phagocytes to engulf pathogens
Some work as helper T cells that stimulate B cells to divide
Some activate cytotoxic T cells
ALL CLONES HAVE THE SAME RECEPTORS
What do cytotoxic cells do?
Destroy infected cells by punching holes in the cell surface membrane using a protein called perforin(drains the cytoplasm)
What is an antibody?
A protein produced by the immune system (B cell) in response to the presence of the appropriate antigen
Describe and antibody
Has 2 antigen binding sites in the tips of the Y
Variable region just below the binding site
The light chains(short one) is one of the angled lines (/)
There is a disulphide bonds between the 2 straight lines (|-|) and each of those straight lines are heavy chain
Receptor binding site at the bottom
From the bottom to the variable region is the constant region
Does an antibody have a Quaternary structure?
What type of molecule is an antibody?
Yes and it’s made by more than one polypeptide chains
Globular proteins called immunoglobulins
How do antibodies bind to antigens?
The antigen binding site has a compliments shape to a specific antigen. They bind to form an antibody antigen complex
How are antibody’s prepared for destruction?
3 ways:
1) agglutination- clumping together of bacteria so phagocytes can easily engulf them
2) attach to bacteria cells and act as marks for phagocytes to engulf cells
3) neutralisation binding to critical parts of the pathogen preventing functioning
What happens in the humoral response?
B cell encounters and engulfs pathogen
B cell presents pathogens antigens
Helper T cell attaches to presented antigens and actives it
B cell divides by mitosis
Clones differentiate into memory cells of plasma cells
Plasma cells secrete antibodies into the blood which help destroy pathogens
Diffrence between primary and secondary response for a vaccine?
Primary- production of antibodies is slower so disease may occur
Secondary- more rapid and more antibodies produced, no disease
What are the types of immunity and define them
Active immunity- Paul’s from immune stale producing memory cells following exposure to an antigen
Passive immunity- results from being given antibodies from a different organism (mother to baby)
Heard immunity- many people are vaccinated so less chance of a non-vaccinated person coming in contact with a infected person and getting the disease
What is artificial immunity?
Active artificial immunity- antigens injected via vaccines, the body produces antibodies
Passive artificial immunity- antibodies are injecting into you to fight the pathogen
How does a vaccine work?
Dead/weakened antigens from pathogen injected. Immune response stimulates memory cells made
How are vaccine made harmless?
Killing the pathogen but leaving the antigens unaffected
Weakening the pathogen
Removing the antigens and injecting them directly
Why can’t/it’s bad to take vaccines orally?
Stomach acid denatures antigens
