pathogen
a disease causing organism
transmissible disease
a disease in which a pathogen can be passed from one host to another
How can pathogens be transmitted?
Direct contact:
Indirectly:
direct contact
the physical transmission of pathogens through direct, person-to-person interaction
indirect transmission
when a pathogen is transmitted without touching an infected person
direct contact example
touch, kiss or body fluid
indirect contact
-contaminated surface
-contaminated food
-air
features of the virus
Have a protein coat
Contain genetic
material (DNA or RNA)
body defense against pathogens
Skin:
Hairs in the nose:
Mucus:
Stomach acid:
White blood cells:
skin
acts as a physical barrier to prevent entry
hairs in the nose
trap dust and microorganisms
mucus
traps pathogens in the respiratory system
stomach acid
kills pathogens in food
white blood cell
destroy pathogens by engulfing them or producing antibodies
Importance of controlling disease spread
Hygienic food preparation:
Good personal
hygiene:
Waste disposal:
hygienic food preparations
reduces contamination and prevents food poisoning
good personal hygiene
(e.g. handwashing) stops pathogens spreading between people
waste disposal
removes sources where pathogens can grow and spread
active immunity
the defense against a pathogen by antibody production in the body.
antigen
molecule on the surface of a pathogen that has a specific shape and triggers the production of antibodies in the body.
key idea about antigen
Each pathogen has its own antigens, which have specific shapes.
antibodies
are proteins produced by the body that bind to specific antigens, helping to destroy pathogens or mark them for destruction by phagocytes.
vaccination process
Weakened pathogens or their antigens are introduced into the body.
Antigens stimulate an immune response, and lymphocytes produce antibodies.
Memory cells are produced, giving long-term immunity.
