Primary/Secodary defences Flashcards
What are the 8 primary defences?
Skin Mucous membranes Cilia HCl Tears Scabs Ear wax Expulsive reflexes
Are primary/secondary defences specific or non-specific? Why?
Non-specific
They stop any pathogen.
How does the skin prevent disease?
Stops pathogens entering the body
How does the mucous membrane prevent disease?
Have goblet cells that make mucus which traps pathogens.
How does cilia prevent disease?
Wafts mucus and trapped pathogens up to throat where they are swallowed
How does HCl prevent disease?
In stomach, kills pathogens
How do tears prevent disease?
Contain the enzyme lysozyme that destroy bacteria
How do scabs prevent disease?
Creates a barrier if skin is broken, blood clots and then heals. Fibrinogen clots the blood. Blood clotting factors activate an enzyme cascade.
How does ear wax prevent disease?
Sticky so traps pathogens
How do expulsive reflexes prevent disease?
Coughing/sneezing expel the pathogens
What is the secondary response?
Phagocytosis
When a pathogen enters the body what do B lymphocytes do?
Release specific antibodies that have complementary shapes to the antigens on the pathogen.
What are some examples of phagocytes?
Neutrophil, macrophage
How do phagocytes recognise a pathogen?
They recognise the constant region of the antibodies attached to the pathogen’s antigens.
What does the phagocyte do when it comes across a pathogen?
It engulfs and ingests them and then expels unwanted things. It can keep antigen so it recognises it next time.
What is it called when the membrane of the phagocyte seals around the pathogen.
Phagosome
How do phagocytes ingest pathogens?
They contain lots of lysosomes (acid and enzymes break down the pathogens)
What is it called when a phagosome and a lysosome fuse together?
Phagolysosomes
Why do histamines increase the temperature around a site of infection?
More difficult for human pathogens to reproduce as they have a preferred temperature that is normally the same as humans core body temperature.
How does blood clot?
Platelets are activated by damaged tissue
Thromboplastin is released into the area around the wound
This enzyme causes prothrombin to be converted into thrombin
Thrombin activates fibrinogen
Fibrin produces a layer of fibres over the wound
New skin is created under the protein mesh.
What happens to the breakdown products of the pathogen in the phagocyte?
The soluble breakdown products are absorbed into the cytoplasm.
The insoluble products are released
The antigens can be kept and sometimes presented.
What can T helper cells produce to signal various other immune cells.
Interleukins
