Immunity Flashcards
What are antigens?
Antigens are surface molecules used to identify cells as ‘self’ or ‘foreign’.
How do lymphocytes defend the body?
Lymphocytes distinguish between self and foreign cells to avoid destroying the organism’s own tissue.
What is a pathogen?
A pathogen is an organism that causes disease
How do viruses harm the body?
Viruses invade host cells to reproduce
How do bacteria harm the body?
Bacteria cause infections
How do fungi harm the body?
Fungi cause infections when they emerge.
How do parasites harm the body?
Parasites live in or on a host
What is the non-specific immune response?
A non-specific response is carried out by phagocytes
What is phagocytosis?
Phagocytosis is the process where a phagocyte engulfs and digests pathogens.
What are the steps of phagocytosis?
- Phagocyte is attracted to the pathogen. 2. Receptors attach to the pathogen’s antigens. 3. Lysosomes move to the phagosome. 4. Lysosomes release enzymes that hydrolyze the pathogen. 5. Products are absorbed and unwanted debris is excreted.
What is the role of neutrophils?
Neutrophils perform phagocytosis and release hydrolytic enzymes to break down pathogens.
What is the role of macrophages?
Macrophages present parts of pathogens as antigens to activate lymphocytes and initiate immune responses.
What is the specific immune response?
The specific immune response is mediated by lymphocytes (B and T cells). It involves clonal selection and clonal expansion.
What is clonal selection?
Clonal selection is the activation of a lymphocyte with a complementary receptor to the antigen.
What is clonal expansion?
Clonal expansion is the division of a selected lymphocyte into identical clones through mitosis.
Where do T cells mature?
T cells mature in the thymus.
What are T helper cells?
T helper cells coordinate the specific immune response by: - Stimulating B cells into plasma cells. - Stimulating phagocytosis. - Activating cytotoxic T cells to kill infected cells.
What are T killer cells?
T killer cells kill abnormal or infected cells by releasing perforin
What are B lymphocytes responsible for?
B lymphocytes are responsible for the humoral immune response and produce antibodies.
How do B lymphocytes produce antibodies?
- Immature B cells divide by mitosis in the bone marrow. 2. Each B cell produces a different antibody receptor. 3. Clonal selection activates the correct B cell
What is the role of memory T cells?
Memory T cells provide long-term immunity by rapidly dividing into plasma cells upon reinfection.
What is the role of plasma cells?
Plasma cells produce antibodies to neutralize or mark pathogens for destruction by phagocytes.
What is the structure of an antibody?
An antibody is a Y-shaped protein with: - A variable region that binds to a specific antigen. - A constant region recognizable by other cells.
What are monoclonal antibodies?
Monoclonal antibodies are identical antibodies produced by dividing hybridoma cells in a laboratory.
How are monoclonal antibodies produced?
- Lymphocytes are stimulated to produce antibodies. 2. Spleen cells producing antibodies are fused with myeloma cells. 3. Hybridoma cells divide and produce monoclonal antibodies.
What are uses of monoclonal antibodies?
Monoclonal antibodies are used in diagnostic tests like pregnancy tests
What is the ELISA test used for?
The ELISA test detects the presence of specific antibodies in a plasma sample.
How does the ELISA test work?
- The antigen binds to the well. 2. A plasma sample with specific antibodies is added. 3. A secondary enzyme-linked antibody binds to the first antibody. 4. Substrate reacts with the enzyme to produce a color change if positive.
What is active immunity?
Active immunity occurs when the immune system produces its own antibodies.
What are the two types of active immunity?
- Natural: After having a disease. 2. Artificial: After a vaccination.
What is passive immunity?
Passive immunity occurs when antibodies are given from another organism.
What are the two types of passive immunity?
- Natural: Antibodies received through breastfeeding. 2. Artificial: Antibodies injected from another source.
What is a live attenuated vaccine?
A live attenuated vaccine uses weakened pathogens that are still alive to stimulate immunity.
What is an inactivated vaccine?
An inactivated vaccine uses virus particles or bacteria that are killed to reduce infectivity.
What are ethical issues surrounding vaccines?
- Animal testing. 2. Prioritization during pandemics. 3. Risk to human volunteers.
How does HIV replicate?
- HIV attaches to T helper cells. 2. Capsid releases genetic material. 3. Reverse transcriptase converts RNA to DNA. 4. Viral DNA integrates into host DNA. 5. Host cell produces viral proteins and assembles new viruses.
How does HIV lead to AIDS?
HIV destroys T helper cells
