Immune response Flashcards
What is a pathogen and how do they cause disease?
An organism that causes disease AND an immune response by destroying cells and releasing toxins
What is an antigen?
A protein with a specific tertiary structure found on the the surface of cells (antigens not found in body are “non-self” or “foreign”) - cause an immune response
What are the defence systems in the body?
- Non-specific (immediate) - physical barrier, phagocytosis
- Specific (slower) - cellular/humoral response
What are the 3 first lines of defence?
HCl, mucus and skin
What is the anagram for phagocytosis?
PREP F E H A M
Phagocyte - white blood cell contains lysosomes
Recognises foreign antigens
Engulfs pathogen
Phagosome (pathogen inside a membrane)
Fuses with a lysosome
Enzymes - lysozymes released into phagosome
Hydrolyse molecules in pathogen
Antigen presenting cell - foreign antigens presented on the..
Membrane (cell surface)
What are the two types of T cell?
- Helper T cells stimulate phagocytes, B cells and cytotoxic T cells
- Cytotoxic T cells kill infected cells by making the membrane fully permeable so cell dies (can’t synthesise viruses)
What is clonal selection?
A specific T cell binds to presented antigen via its complementary receptor –> T cell activated and produces clones by mitosis to produce many T cells with complementary receptors to the antigen –> become either TH or TC cells
What is the anagram for the cellular response?
An Armadillo Starts To Crawl Can He Stop Before Passing (out)
Antigen presenting cell will
Activate a
Specific
T cell which will
Clone by mitosis, forming
Cytotoxic T cells which kill infected cells
Helper T cell
Stimulates
B cells
Phagocytes
What is a B cell?
A white blood cell responsible for producing antibodies - each produce a specific antibody
How are specific B cells activated?
Has protein receptors that are complementary to an antigen presented by a phagocyte or a receptor on an activated helper T cell - when these bind B cell is activated
What is the anagram for the humoral response?
Trevor Always Back Chats PAM
T helper cell
Activates
B cell (specific)
Clones by mitosis to form
Plasma cells which secrete
Antibodies
Memory cells formed
What is the secondary immune response?
More antibodies produced more quickly
What is the structure of an antibody?
- Variable region (complementary to 1 antigen)
- Constant region (same in every antibody)
- Antigen-antibody complex
What are monoclonal antibodies?
Have the same tertiary structure and produced from the same plasma/B cell
How are monoclonal antibodies used in treating/diagnosing cancer?
- Monoclonal antibody complementary to cancer cell antigen binds to tumour markers on cancer cell
- Treatment - maintains high drug concentration at tumour site
- Diagnosis - tissue examined under microscope, fluorescent tag shows up for complementary antibody