Non-Specific Body Defences Flashcards
What is a pathogen?
A pathogen is a bacterium, virus or other organism that can cause disease/harm.
What is an antigen?
Antigens are molecules, often proteins that are located on the surface of cells that trigger an immune response.
What is the difference between a physical barrier and a chemical barrier against diseases?
Physical barrier - physically prevents the entry of infection.
Chemical barrier - destroys pathogens before infection.
What are our physical defences against diseases?
One physical defence are the closely packed epithelial cells that are found in the skin and inner linings of the digestive and respiratory systems.
What are our Chemical defences against diseases?
The chemical defences include secretions like tears, saliva, mucus and stomach acid.
Describe and explain the inflammatory response:
This is when histamine is released by mast cells causing vasodilation and increased capillary permeability. The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.
What are phagocytes?
Phagocytes are white blood cells which recognise pathogens and destroy them by phagocytosis.
What is phagocytosis?
Phagocytosis is the engulfing of pathogens and their destruction by digestive enzymes contained in the lysosomes.
What are the steps of phagocytosis?
- The macrophage begins to surround the pathogen.
- The macrophage surrounds and engulfs the pathogen.
- The pathogen is enclosed in a phagocytic vesicle within the cytoplasm of the macrophage
- The lysosome fuses with the phagocytic vesicle releasing digestive enzymes.
- Products of digestion are released into the cytoplasm of the macrophage.
What are cytokines?
Cytokines are protein molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection.
