Response To Infection topic 6 Flashcards
Physical barriers
- lysozyme in tears
- skin surface (flora)
- digestive system (gut flora)
- mucus lining trachea
Non specific responses
- inflammation
- phagocytosis
- interferons
- lysozyme
Specific responses
T cells
B cells
(Lymphocytes)
WHITE BLOOD CELLS- Lymphocyte
Involved in specific immune response
- type of leukocyte
- in blood and lymph nodes
- recognise antigen molecules on surface of pathogen and co ordinate response
- large nucleus
WHITE BLOOD CELLS- neutrophil
Lobed nucleus- diapedesis Phagocytosis: 1. Migration and diapedesis 2. Opsonisation (tagging as foreign) and recognition 3. Ingestion
WHITE BLOOD CELLS- Macrophage
Phagocytosis
- activation of lymphocytes
- tumour killing
- fever and inflammation
- tissue repair by collagenase
- arrives at infection later than neutrophils as live longer
- involved in antigen presentation
WHITE BLOOD CELLS- monocytes
Become macrophages
WHITE BLOOD CELLS- basophils
Produce histamine- allergic response
WHITE BLOOD CELLS- Eosinophil
Allergic response or in response to parasites
Process of inflammation
- Pathogens enter damaged tissue. Damaged cells release chemical substances that act as inflammatory mediators- histamine.
- Chemicals cause increase in blood flow and permeability of capillary. =Flooded with fluid and blood clotting elements causing swelling and redness.
- Tissue cells release chemicals that attract phagocytic white blood cells such as neutrophils and macrophages.
- Phagocytosis begins when wbc recognises pathogen as foreign
- The cell membrane of the macrophage fuses around bacterium trapping it inside a phagosome.
- Phagosome fuses with a lysozyme= phagolysosome. Bacterium is broken down and digested
- Macrophage absorbs useful material and expels the rest
- Anti inflammatory factors reduce swilling and skin heals
What are the 2 main specific responses?
Cell mediated- targets pathogens inside cells
Humoral- target pathogens in body fluid with antibodies
Cell mediated specific response process
- When a macrophage destroys the pathogen it displays the pathogens antigen on it’s cell-surface out of the MHC that signals it is part of the body. It is an antigen presenting cell.
- Release of interleukin 1 attracts T helper cells. One T helper will be complimentary to the displayed antigen and bind.
- T-helper cell will release interleukin 2 stimulating the growth and development antigen-specific T killer cells. It will make copies of itself.
- T killer cells detect the antigen on infected body cells and produce perforin which target the cell membrane allowing water in which causes cell lysis.
- Some of the cells developed will be T memory cells in case the body is infected again.
Humoral immune response process
- When a macrophage destroys the pathogen it displays the pathogens antigen on it’s cell-surface out of the MHC that signals it is part of the body. It is an antigen presenting cell.
- Release of interleukin 1 attracts T helper cells. One T helper will be complimentary to the displayed antigen and bind.
- T-helper cell releases interleukin 2 stimulating effector B cells to become plasma cells
- Plasma cells divide and produce antigen-specific antibodies which are released and attach to pathogens
- Some of the B effector cells develop into B memory cells instead of plasma
How is fever produced
Pyrogens
When a pathogen infects the body the hypothalamus rests the temp to higher than 37
Advantages of fever
Pathogens reproduce better below this
Specific immune response works better higher temperature
Body temperature following bacterial infection
Temperature rises steadily and remains high until infection ceases
Body temperature following viral infection
Temperature spikes shooting high every time viruses lyse cells
How antibodies inactivate pathogens- neutralisation
They bind to antigens and prevent pathogens from attaching to and entering host cells. This encourages macrophages to destroy the pathogen.
How antibodies inactivate pathogens-agglutination
They bind to antigens on many pathogens clumping them together so they are too big to enter cell. Macrophages can recognise and destroy them.
Types of adaptive immunity
Natural-active (infection) passive (maternal)
Artificial-active (vaccination) passive (Ab transfer)
What is herd immunity
Indirect protection from infectious disease that occurs when a large percentage of the population are immune so the chains of infection are destroyed
When do you need to increase the percentage of immunity for herd immunity
It’s a pathogen has a higher reproduction number which is how many people one infected person will infect
Why is the MMR vaccine more effective than single vaccinations
The uptake was increased if people got them done all at once
Pros of the MMR vaccination
One. Individual protection from harm and death.
Two. Benefit to society-herd immunity
Three. Reduction on treatment cost as less cases are developed.
Cons of the MMR vaccination
One. Allergy to eggs.
Two. Reaction to the vaccination some brain damaged/ died in early development.
Three. Link to rise and asthma and allergies?
Four. vaccinating for the benefit of society over individuals.
