3.5 Flashcards
what is a pathogen
any organism that can cause disease
what is immunity
the ability of the body to resist infection by a pathogen or to destroy the organism if it invades the body
summarise non specific immune responses
not targeted at a specific pathogen
summarise specific immune responses
targets a specific pathogen
give an example of a physical defence
skin - epithelial cells are a barrier
give an example of a chemical defence
tears lysine enzyme breakdown cell walls
mucus traps pathogen
skin and stomachs secretions kill pathogens
what do mast cells do
activate and release histamine
what to phagocytes do
engulf pathogens
what does histamine do
causes blood vessels to dilate and become more permeable
what do clotting factors do
seals the wound
describe the prices of inflammation
• injury activates mast cells which release histamine
• area becomes red and inflamed, capillaries leak fluid into neighbouring tissue
• increased blood flow leads to an accumulation of phagocytes , clotting factors arrive
what do phagocytes release
cytokines
what do cytokines do
proteins which act as a signal attracting more phagocytes
describe phagocytes
- phagocyte recognises pathogen
- engulfs pathogen and vacuole forms in the cell that contains pathogen
- bacterium is trapped some lysosomes move towards the vacuole and fuse
- bacterium is digested by enzymes
