Download Unit 2 Biology Test Chapter 31.2

Saturday, November 8, 2014
Immune System and Disease
Immune System
- The immune system is the body system that fights off infection and pathogens.
- The immune system relies on physical barriers to keep pathogens out.
- Your skin is your body’s first line of defense. The skin physically blocks invading
pathogens.
- The skin is hypertonic and acidic.
- Once pathogens are inside, the immune system relies on the circulatory system to
send chemical signals to coordinate an attack and to transport specialized cells to
infection.
- Once pathogens get past all of your outer defenses, the cell of you immune system
spring into action.
- White blood cells find and kill pathogens that have gotten past eh body’s external
barriers.
- A phagocyte is a cell that engulfs and destroys other cells. It comes from Greek words
that translate to mean “cell eater”.
- T cells destroy body cells that are infected with pathogens.
- B cells produce proteins that inactivate pathogens that have not yet infected a body
cell.
- The
immune
systems
uses
there
types of
proteins
to fight
off
invading
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Saturday, November 8, 2014
pathogens: complement proteins, antibodies, and interferons.
- Complement proteins are made by white blood cells and by certain organs.
- Some complement proteins weaken a pathogen’s cell membrane, allowing water to
enter the cell and cause it to burst. Others attract phagocytes to the infected area.
- Antibodies are proteins made by B cells. Antibodies destroy pathogens in one of three
ways. Antibodies might make the pathogens ineffective by binding to the pathogen’s
membrane proteins. Antibodies might also cause pathogens to clump, making them
easier for phagocytes to engulf and destroy. Other antibodies activate complement
proteins that weaken the pathogen’s cell membrane.
- Interferons are proteins produced by body cells that are infected by a virus. Cells
release interferons, which stimulate uninfected body cells to produce enzymes that
will prevent viruses from entering and infecting them. If viruses cannot enter healthy
cells, they cannot reproduce. Other interferons stimulate an inflammation response.
- There are two types of immunity-passive and active.
- Passive is immunity that occurs without the body’s undergoing an immune response.
- Passive immunity is transferred between generations through DNA and between
mother and child.
- Some viruses can be spread between different species.
- Genetic immunity is immunity that a species has because a pathogen is not
specialized to harming that species.
- Active immunity is immunity that your body produces in response to a specific
pathogen that has infect or is infecting your body.
- Acquired immunity is a type of active immunity that occurs after you immune system
reacts to a pathogen invasion.
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