Primary non-specific defences
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What is non-specific defence?
It doesn’t distinguish on pathogen from another
What is specific defence?
Recognition of a pathogen by lymphocytes and immunity is developed
What are the non-specific defence mechanisms?
First and second line of defence
What is first line of defence?
Skin, mucous membranes and secretions of skin
What is second line of defence?
Phagocytic white blood cell, anti-microbial proteins and inflammatory response
What is the specific defence mechanism?
Third line of defence
What is the third line of defence?
Lymphocytes, antibodies and memory cells
What are the 2 types of disease transmission?
Horizontal and vertical
What is horizontal transmission?
From person to person
What is vertical transmission?
From parent to unborn child
What is the purpose of primary defences?
Stop pathogens from entering body
When is secondary defences used?
If pathogens are in the body
What is direct transmission?
Contact with another person, breaks in skin and ingestion
What is indirect transmission?
Droplets on surface, inanimate fomites and vectors
How does the stomach quickly expel contents?
The vomiting reflex
What is the purpose of vomiting?
To quickly remove harmful substances from the gut
What is function of diarrhoea?
A host defence to eliminate the pathogen or it may be a pathogen microbial adaptation to ease/allow transmission to other hoss
He is the eye adapted as defence?
Tears wash away and blinking drains fluid, lysosome present in tears (degrades peptidoglycan in bacterial cell walls) so is anti-microbial and macrophages present
How is the body adapted defence to airborne transmission?
Trachea contains mucous and epithelial cells which trap particles and beat up to throat to be swallowed and in alveoli, many macrophages phagocytose any particles missed by mucous
How is the skin adapted to defence?
There is a high NaCl concentration in sweat so is osmotically stressful for microbes, antimicrobial substances produced on skin surface and it regenerates
What is the structure of the skin?
It is made of hard layers of dead cells, is very dry and has a pH of 5.5
Why is the nose and mouth adapted to defence?
Gastrointestinal tract is major entry point for pathogens as tears, saliva and lung secretions swallowed
How is the nose and mouth adapted to defence?
Saliva contains the enzyme lysosome and general antibodies, throat restricts airflow so microbes settle out and nose filters air which traps microbes in nasal mucous
How is the stomach adapted to defence?
It has a very low pH, a thick layer of mucous, contains protein digesting enzymes which denature toxins and stomach lining cells are constantly shed as food scrapes past so hard for pathogens to attach