Immune System Book 6 Flashcards
What are pathogens?
Microorganism what cause disease
How do pathogens cause disease?
- ) host cells by entering, reproducing and leaving(cells burst)
- ) produce and release toxins which damage host cells
5 ways pathogens can transmit?
- ) contaminated food and water eg chlorea
- ) air borne eg flu
- ) sexual intercourse eg hiv
- ) blood to blood eg hiv
- ) mother to foetus eg rubella
What are antigens?
Molecules that cause an immune response
5 facts about antigens
- located in the cell membrane of pathogens
- found on the surface of viruses
- exist as free molecules, such as a toxin
- found on the surface of a tissue or organ transplant
- found in the cell membrane of cancer cells
Name 3 non specific defence mechanisms and how they work
Skin- contains dead cells which contain keratin acting as a barrier
Mucus-lining of respiratory passages, traps MOs
Lysozyme-present in saliva and tears containing enzymes which kill microbes
2 specific defensive mechanism s
Cellular and humoral response
2 types of white blood cells
Phagocytes- antigen presenting cells
Lymphocytes- include t and B cells
Where do b and T cells come from
Bone marrow
5 types of t and B cells
Cytotoxic T, helper T, memory T, B cells, memory b
What makes T cells specific?
- specific receptor proteins on their surface membrane
- receptor proteins have specific tertiary structure so shape or binding site is specific
What makes B cells specific?
Have antibody proteins in their surface membrane. The antibody has specific tertiary structure so shape of binding sites is specific.
Explain th structure of an antibody
It is a protein with a quaternary structur, each molecule is made up of 4 polypeptide chains to form a Y shaped molecule. Each antibody has 2 binding sites so that more than one antigen-antibody complex can form at once stopping the mov met of more than one pathogen.
Where can antibodies be found?
- surface of membranes of B cells
- blood stream
- in tissue fluid
- in breast milk
What’s a vaccine?
A preparation of antign from a pathogen that will generate a primary immune response when injected into an individual
Process of phagocytosis?
1- phagocytes are attracted to chemicals released by pathogens
2- phagocytes engulf pathogens and enclose them inside a membrane vesicle
3- lysosomes fuse with the phagosome releasing their hydrologic enzymes into it
4- enzymes digest the pathogens molecules killing the pathogen
5- pathogens antigens are displayed on the surface of the phagocytes cell membrane
6- T cell and B cells can bind to the antigen and this stimulates an immune response
What’s clinal selection?
When t and B cells divide rapidly by mitosis producing genetically identical cells
When does a secondary immune response occur ?
When T and B cells encounter the same pathogen again. Memory cells are activated when their surface receptor or antibody binds to antigen on the pathogen causing T cells to rapidly activate B cells. More antibody antigen complexes form faster so the pathogen is quickly killed
What is antigen variability?
When pathogens undergo mutations which changes their antigen protein shape. Stops secondary immune response from being stimulated
When does the secondary immune response form again?
When T and B cells encounter the same pathogen
Explain the secondary immune response
Memory T and B cells are activated when their surface receptor or antibody binds to antigen on the pathogen. This causes T cells to rapidly activate B cells. B cells rapidly produce and then release more antibodies. More antibody-antigen complexes form faster, this kills the pathogen quickly before any symptoms can be produced.
What does antigen variability mean?
Surface proteins on memory cells will not be able to bind to antigens on a pathogen and thus a secondary immune response cannot be stimulated and instead of primary response is triggered
5 types of vaccine?
1- killed pathogen, antigens on surface still stimulate immune response 2-live virus 3- modified toxin 4- isolate pathogen antigens 5- genetically engineered antigens
When is vaccination not successful?
Certain peopl have weak immune systems, memory cells eventually die, pathogens show antigen variability, when individuals opt ou of vaccination
Passive immunity vs active
Passive doesn’t require exposure to antigen, protection is immediate, memory cells are mot produced, protection is short term. Active is the opposite.
What are monoclonal antibodies?
Antibodies that are identical because they are produced by one type of B cells that are clones
Uses of monoclonal antibodies
Cancer treatment- anti canc t drugs are attached to monoclonal antibodies.
Medical, diagnosis- ELISA checks if a patient has an antibody to a certain antigen in their body
