Body Defences Flashcards
What are body defences?
- non-specific (innate) 1st and 2nd line
- specific (adaptive) - 3rd line of defence
What are self cells?
- recognised by the immune system as being a normal part of the body by unique markers
What are non-self cells?
- eg. pathogens, cancer cells, transplant tissue)
- contains markers or antigens that result in an immune reaction
What is an antigen?
- anything that are recognised as ‘non-self’ by the immune system and so can cause a response
- eg. pathogens or part of the pathogens that are considered ‘antigenic’
What are the general properties of non-specific?
- do not distinguish between threats
- react same each time as first time
- present at (before) birth
- 2nd line defences respond to tissue damage by pathogens or mechanical means
Skin and skin glands.
- sebum inhibits growth of bacteria
- sweat can feed bacteria
- sensible perspiration contains an antibiotic agent
- CO2 changes pH of skin to acidic
Interferons (IFNs).
- cytokines
- small proteins from macrophages and tissue cells infected by viruses
- signal other cells to defend themselves
- can be drugs - alpha-interferon
Complement.
- proteins which kill bacteria
Fever.
- high body temp (>37.2)
- speeds up defences
- slows down bacterial growth and viral replication
Phagocytes.
- 2nd line of defence
- inside tissues
- fixed phagocytes reside in tissues
- free phagocytes move through blood (macrophages)
Lymphatics.
- phagocytes travel through lymph vessels to lymph nodes
Inflammation.
- non-specific defence mechanism
Adaptive (specific) defence system
- 3rd line of defence - mounts attack against particular foreign substances
What protects the body against antigens?
T cells and B cells
What are T cells?
- manage the immune response
- attack and destroy foreign cells and infected cells
What are B cells?
- produce plasma cells which secret antibodies
- antibodies immobilize antigens
What are interleukins?
- increases T cell sensitivity
- stimulate B cell activity, plasma formation, antibody production
- enhance non-specific defences
- moderate the immune system
What is TNF?
- tumour necrosis factors
- slows tumour growth
What is CSF?
Colony Stimulating Factors
What are 2 ways to activate B cells?
- phagocytes (APC) engulfs bacteria and presents antigens to helper T cells
- antigen attaches to antibodies on surface of B cells
What is antibodies?
- made against antigens
- stay in blood and lymph nodes or attached to B cells
- can be measured in blood - titer
- 1 antibody type for each antigen
What is IgG?
- major immunoglobulin in the blood
- able to enter tissue spaces; works efficiently to coat pathogens speeding destruction by other cells in immune system
What us IgD?
- found inserted into the membrane of B cells where it somehow regulates the cell’s activation
What is IgE?
- normally present in only trace amounts, but is responsible for the symptoms of allergy
