Immunology Flashcards
Describe the difference between active and passive immunity.
Active - memory cells
- antibody production by memory
- long term
- takes time to develop
Passive - no memory cells
- antibodies introduced from outside
- short term
- fast acting
How does a vaccine lead to the production of antibodies against a disease-causing organism.
- vaccine contains antigen
- phagocyte presents antigen on surface
- specific t-helper cell with specific receptor binds to complimentary region
- stimulates B cell
- B cell divides by mitosis to form plasma cells
- secretes antibodies
- antibodies remain in blood
What is an antigen?
- molecule that stimulates and immune response that results in the production of a specific antibody
Describe the process of non-specific immunity.
- pathogen engulfed by phagocyte
- phagocyte enters in a vesicle = phagosome
- lysosomes fuse with phagosome releasing hydrolytic digestive enzymes
- hydrolyses pathogen
- waste materials released by exocytosis
- antigens presented on cell surface membrane
- phagocyte becomes antigen-presenting cell
Describe the cell-mediated response.
- T-helper cell with specific receptor molecule binds to APC
- activates and clones by mitosis
- forms memory T-cells
- cytokines released attracting phagocytes to area of infection
- activates cytotoxic killer T (locates and destroyers infected BODY CELLS)
- activates B cells
Describe the Humoral response.
- activated by specific complimentary t-cell
- TH cell releases cytokines that signal B-cells to multiply by mitosis
- produces plasma cells (produces antibodies and release into blood plasma)
- produces memory cells
(Remain in body for a rapid and extensive response upon second infection)
How do antibodies destroy pathogens?
- AGGLUTINATION = clump together
- OPSONISATION = mark pathogens for phagocytes
- LYSIS = destroy membrane
- prevent pathogen replication
Uses of monoclonal antibodies
- research
- testing kits e.g. pregnancy
- killing specific cells
- isolating specific chemicals
Describe the process of HIV replication using TH cells.
- protein on HIV binds to cell surface membrane
- capsid fuses and releases viral RNA into t helper
- HIV’s reverse transcriptase converts viral RNA to cDNA using host nucleotides
- Viral cDNA moves into nucleus of T helper = INFECTION
- transcription of viral DNA to mRNA = HIV proteins
- new virions
- particles break from T helper cell
- reduction in number of t helper cells
What is an antibody?
Protein made in response to foreign antigen with a binding site to specific antigen
How does HIV cause the symptoms of AIDS
- cell mediated immunity compromised
- fewer T cells
How do ELISA tests work?
- uses monoclonal antibodies
- detects certain substance
- monoclonal antibodies fixed to surface of test wall
- second monoclonal antibody with enzyme added and also binds to molecule
- substrate added - chemical colour change
- colour change = positive result
What is herd immunity?
- enough individuals in the population are vaccinated, so little chance of disease spreading
