Immune System Flashcards
Disease
any conidition in which the body or parts of the body do not function properly
Infectious disease
diseases that are caused by pathogens
Main ways disease is spread
direct contact with an infected person, animal or their discharges
Contaminated food and water
Disease-carrying insects
pathogen
harmful disease causing organism
Bacteria infections are treated with
antibiotics
contagious infection
Spread by physical contact
How is death measured
CFR (case fatality ratio) the percentage of infected people that die from it
How is contagiouness measured
the average number of people that an infected person passes the disease to, assuming R0
what is R0
assumption that no-one is protected by vaccination or previous exposure to the disease
Immune system
Special organs, cells and chemicals that fight infection (microbes)
Main parts of immune system
white blood cells
antibodies
complement system (proteins that assist defence e.g. burst open infected cells)
lymphatic system
spleen
bone marrow
thymus
How many lines of defence
3
1st line of defence
physucal barriers to prevent infection
Skin
It forms a physical barrier between the body and the outside environment
Outer layer of skin
he epidermis, consists of dead cells filled with the protein keratin. These cells form a tough, waterproof covering on the body, difficult to get in.
Inside of mouth and nose are lined with
mucous membranes
Other organs that are exposed to substances from the environment are
lined with mucous membranes
mucous membranes produce
mucous
Mucus is
sticky, moist secretion that covers mucous membranes. The mucus traps pathogens and particles so they can’t enter the body.
any mucous membranes are also covered with
cilia
Cilia
tiny, hair-like projections that move in waves and sweep mucus and trapped pathogens toward body openings
Biological 1st line
millions of bacteria that compete with harmful bacteria for food and space. They prevent the harmful bacteria from multiplying
Chemical barriers 1st line
Variety of fluids, including tears, saliva, and sweat.
fluids contain enzymes called
lysozymes which break down the cell walls of bacteria and kill them