Immunity Flashcards
3 physical defences to infection:
.Skin (protein keratin)
.Trachea and Bronchi (mucus production)
.Stomach and gut (HCl acid)
2 types of phagocytes and their roles:
-Neutrophils : Smaller and involved initiating immediate response
-Macrophages : Bigger and involved in specific immune response
2 types of lymphocytes and what form can they be in:
-T lymphocytes, could be helper, cytotoxic, killer or memory cells
-B lymphocytes, could be memory or plasma cells
Two specific responses to pathogens:
.Cellular (cell mediated) - highly specialised cells that target pathogens inside cells, T cells, T helper cell recognizes antigen of virus presented by macrophage
These activate T killer cells which will destroy infected host cells.
Also activates B cells to be an antigen presenting cell (to self), B plasma cells that produce antibodies.
.Humoral (antibody mediated) - targets pathogens in body fluids with antibodies, B cells
Body’s non specific responses to pathogens:
.Inflammation = Histamines released by mast cells that cause vasodilation, Increased permeability of capillaries that helps bring white blood cells to affected site, leave the blood and enter the tissue.
Cytokines released.
.Phagocytosis = Phagocyte engulfs pathogen, forms phagosome
Lysosome fuses with phagosome and Lysozyme enzymes break down pathogen
.Fever = Inhibits replication of virus
What is antigen presenting cell?
When white blood cell engulfs pathogen and present antigens on the surface
What are interleukins?
T helper cells produce these in cell mediated and humoral response to stimulate more T cells as well as B cells to be produced.
Cell mediated = stimulates production of both
Humoral = stimulates production of B cells
In humoral immunity what cell engulfs pathogen?
B cells
What binds to antigen of B cell to produce interleukins?
T helper cells
What do immunosuppressant drugs do?
Prevent immune system from attacking ‘self’ antigens, prevents organ and stem cell transplant rejection.
Pathogens are coated in opsonins, what is their role?
Help phagocyte bind to pathogen in phagocytosis
How does HIV virus create infection at T Helper cell?
1)Attach to CD4 receptor on host cell membrane
2)Viral RNA and reverse transcriptase released inside and used as template to produce complementary strand of DNA
3)Uses host cell’s enzymes to produce more viral components
How does HIV develop into AIDS?
HIV particles replicate inside T helper cells,
killing or damaging them.
AIDS develops when T helper cell levels are low.
Individual unable to kill other pathogens.
How can mutations in HIV affect body’s specific immune response?
1)Mutation will happen that will change antigen (glycoprotein) in
surface of virus
2)Memory cells won’t recognize new antigen
3)Secondary immune response not possible so another primary response needed, to present new antigens
What engulfs TB bacteria when it’s inhaled?
Macrophage
Stages of TB?
1)Primary Infection
2)Latent TB infection
3)Active TB infection
What happens in primary infection?
Bacteria may be able to survive and reproduce in the macrophage, healthy people won’t develop TB at this stage
How do bacteria then become dormant?
When the infected macrophage becomes encased in structures called tubercles
What do the TB bacteria do to damage lung tissue?
Prevents lysosome from forming in the macrophage, so multiplies rapidly
2 ways that HIV evades the immune system:
-Frequent mutations
-Invade host cells so antigens can’t be detected
2 adaptations of gut to prevent pathogens entering body:
1)Acidic conditions which denature enzymes of microorganisms
2)Gut flora (bacteria) will outcompete other microorganisms, inhibiting growth and reproduction of pathogens
Define conjugation:
Exchange of plasmids that allow mutations to pass between bacteria
How do hospitals minimise spread of antibiotic resistant bacteria?
- Quarantine of affected patients
-Antibiotics only prescribed if necessary, course completed to ensure no bacteria left behind to mutate
-Hygiene code of practice including antibacterial gels
Different names given to interleukins:
Cytokine, lymphokine, monokine, chemokine
What is a reverse transcriptase in HIV?
Enzyme used to produce DNA from viral RNA
How can interferon help against viruses?
Cells infected by virus produce interferons, these prevent viruses attaching to uninfected cells
Also reduces replication of viruses by inhibiting production of viral proteins
