Phagocytes
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What is phagocytosis?
A form of endocytosis where large particles (e.g. cell debris) are taken up into vesicles and are fused with a lysosome so degraded products are recycled if useful
What is a phagocyte?
Cels which can ingest particles from the surrounding
What is an antigen?
A molecule that stimulates an immune response
What is the immune response?
A specific response to a pathogen which involves lymphocytes and antibodies
What are types of non-specific defences?
Blood clotting, inflammation, wound repair and phagocytes
What is the purpose of blood clotting?
To seal off wound
What is the purpose of inflammation?
Histamine causes cells to release cytokines messenger molecules that increase inflammation and fever
What is the purpose of wound repair?
To regenerate tissues using collagen
What are types of phagocytes?
Neutrophils and macrophages
What are the goals of secondary defences?
Neutralise any toxins produced by pathogens, prevent pathogen multiplying, kill pathogen and remove any remains of pathogen
What are the 3 types of phagocytes?
Monocytes, macrophages and granulocytes
What are monocytes?
Not mature phagocytes
What are macrophages?
They are free or fixed
What are granulocytes?
Basophils, neutrophils and eosinophils
Where are neutrophils made?
In bone marrow
How do neutrophils move?
They travel in the blood and squeeze through tissues through capillaries so can rapidly exit into tissues
What is the lifespan of neutrophils?
They are short lived and are released in large names when an infection occurs and form pus when they die
What is the structure of neutrophils?
They have lysosomes and a very effective cytoskeleton
What can neutrophils respond to?
Histamine and cytokines
How are neutrophils attracted?
Damaged and infected cells release histamine and capillaries are leakier
What is the result of histamines?
More fluid causes swelling and more tissue fluid which washes pathogens into lymph nodes where macrophages wait
Where are macrophages made?
In bone marrow
How do macrophages move?
They are stationary or mobile so can travel in monocytes or settle in tissues (especially lymph nodes) and develop into macrophages
What is the lifespan of macrophages?
They are long lived