Immune System. Means of Defense (3 categories). First two are Nonspecific A. Barriers Doesn’t distinguish between agents Helps Prevent Entry into the body Includes skin and mucous membranes which provide a mechanical and chemical barrier
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The immune system learnsto distinguish “self” from “non-self”
Detects “antigens”- foreign substances . These cause an increase in the cells that attack or produce antibodies. They may be things like molecules on surfaces of viruses and bacteria or marker molecules on transplanted organs.
The immune response must be activated by the presence of an antigen
The response is specific for a particular foreign substance or invader
The system remembers the antigens after the initial contact. There is a quick response the second time. This is memory.
Vaccination- immune response is prevented with a nonvirulent or weakened form of a pathogen-initiates long term capability to respond quickly to real infective agent.
-Active immunity- body produces antibodies
-Passive immunity- body acquires antibodies from other sources such as placenta, injection, immunity is temporary