Biology - Immunology
Terms in this set (38)
What is cell-mediated immunity?
an immune response that does not involve antibodies but involves T lymphocytes. Respond to antigens on a cell rather that inside.
What is humoral immunity?
antibody-mediated immune response
What are the body's own cells described as?
What are foreign cells described as?
Examples of non-self cells
Pathogens, cells from other organisms of the same species, toxins, abnormal body cells e.g cancers
2 types of non specific immune responses
Physical barriers and phagocytosis
2 types of specific immune response
cell-mediated and humoral response
How do lymphocytes distinguish between self and non-self cells?
Self cells have antigens that identify them as so
What are cells that display foreign antigens on their surface called?
Antigen presenting cells (APC's)
Describe the immune response
1) Pathogens invade the body
2) Leave trail of toxins in a conc. gradient
3) Phagocyte goes up conc. gradient
4) Receptors on surface attach to pathogen
5) Shape of phagocyte manipulated to form a phagosome
6) Lysosomes within the cell containing lysozymes move towards the phagosome
7) Lysosomes release lysozymes that hydrolyze the pathogen
8) Insoluble substances ejected via exocytosis, soluble substances absorbed
9) Phagocyte absorbs pathogens's antigen via endocytosis and presents it on cell surface, becomes APC
10) Helper T cell with complementary receptor attach to phagocyte
11) Mass mitosis of that specific TH cell called clonal selection
12) These TH cells can do 4 things:
Become memory T cells
Stimulate B cells to become plasma cells
Increase phagocyte response
Stimulate cytotoxic T cells
Role of plasma cells
cells that produce antibodies. Replicate very quickly
Role of memory cells
Circulate in blood and tissue fluid. When they encounter the same antigen they divide rapidly into more memory and plasma cells
structure of antibody
2 heavy chains, 2 light chains. Binding site called the variable region, there are two of these. Rest of antibody called the constant region
Role of antibodies
Bind two pathogens together - agglutination. Makes it easier for phagocyte to perform phagocytosis. Also stimulate phagocytes to engulf pathogens they're attached to.
What is it called when an antigen binds to an antibody?
What is the binding site of an antibody called?
What is the constant section of an antibody called?
What are monoclonal antibodies?
Antibodies produced from a single group of genetically identical B-cells
How do monoclonal antibodies treat cancer?
Attach to antigens on cancer cells and block the chemical signals that stimulate their uncontrolled growth
What is monoclonal antibody therapy?
Attaching a radioactive or cytotoxic drug to the monoclonal antibody. When it binds to cancer cell it kills it.
How do cytotoxic T cells kill?
secretion of perforin and granzyme; perforin creates pores that allow granzyme to enter the target cell and activate apoptosis
Ethical use of monoclonal antibodies
Production of monoclonal antibodies involves mice, deliberately causing cancer in them. Use in multiple sclerosis had caused death. Testing of the safety of drugs presents dangers.
What is passive immunity?
Introduction of antibodies from an outside source, no direct contact with pathogen. No memory cells produced.
What is active immunity?
Stimulating production of antibodies by the individuals own immune system. Long lasting.
2 types of active immunity
natural and artificial
What is natural active immunity?
Results from an individual becoming infected with a disease under normal circumstances
What is artificial active immunity?
Inducing immune response without suffering symptoms i.e. vaccination.
Features of a successful vaccine
-Economically available in sufficient quantities to even the most vulnerable population
-Little/no side effects
-Means of producing, storing and transporting
-Means of administering
-Possible to vaccinate the vast majority of population to produce herd immunity
What is herd immunity?
immunity in most of a population to protect those that are not vaccinated
In a population, which demographic may no be vaccinated?
Babies and very young children
Why can vaccinations not eliminate a disease?
-Vaccinations can't induce immunity to everyone e.g those with defective immune systems
-May get illness immediately after vaccination but before immune response
-Individuals may have objections to vaccinations e.g. religion
Ethics of vaccinations
-Production involves animals
-Possible long-term side effects
-Who should vaccinations be tested on?
What does HIV stand for?
human immunodeficiency virus
What illness does HIV cause and what does it stand for?
AIDS - acquired immune deficiency syndrome
What type of virus is HIV?
How does the HIV virus replicate?
1) HIV enters bloodstream and circulates around the body
2) Protein called CD4 binds to protein on HIV. This is most frequently on helper T cells
3) Protein capsid fuses with cell-surface membrane
4) RNA and HIV enzymes enter helper T cell
5) HIV's reverse transcriptase converts virus's RNA to DNA
6) New DNA moved into helper T cells nucleus and into it's DNA
7) HIV DNA in nucleus creates mRNA. Has instructions for making new viral proteins
and RNA to go into new HIV virus
8) mRNA passes out of nuclear pore, use cell's protein synthesis mechanisms to make HIV particles
9) HIV particle breaks away from T helper cell with a piece of it's cell-membrane surrounding them - lipid envelope
How HIV causes the symptoms of AIDS
Attacks helper T cells. Without them, immune systems can't B cells to produce antibodies or cytotoxic T cells. Memory cells become infected or destroyed.
Why are antibiotics ineffective against viral diseases like AIDS
One way antibiotics work is preventing bacteria from making normal cell wall. In bacteria, antibiotics inhibit enzymes required for synthesis and assembly of peptide cross-linkages in bacterial cells walls making them unable to withstand pressure so the cell bursts. Viruses rely on host cell to carry out metabolic processes so lack cell structures. Therefore, ineffective as no metabolic mechanisms or cell structures to disrupt. Also, have protein coat not murein cell wall so no sites where antibiotics can work.
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