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12.2 Notes – The Immune System
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Immune system – a combination of body
defenses made up of cells, tissues, and
organs that fight off pathogens
5 major protective barriers:
1. Tears – have chemicals that kill and/or wash away
pathogens
2. Saliva – destroys harmful organisms in your
mouth
3. Skin – protective barrier unless your blood is
exposed by a cut
4. Stomach acid – destroys pathogens in the
stomach
5. Mucous membranes – they trap pathogens
12.2 Notes – The Immune System
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What does your body do when a pathogen
enters the body?
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Blood supply increases
Circulation slows down
Raises the blood pressure
Fluid leaks from blood vessels
Tissues swell
Phagocytes attack the pathogens and “eat” them
inflammation – body’s response to injury or
disease, resulting in a condition of swelling,
pain, heat, and redness
12.2 Notes – The Immune System
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interferon – a protein that defends the body by
fighting the infection and stopping viruses
lymphatic system –a secondary circulatory
system that helps the body fight pathogens
and maintain its fluid balance
lymphocytes – special white blood cells in the
lymph
3 types of lymphocytes:
1. B – in the bone marrow
2. T – in the thymus gland
3. NK (natural killer cell) – attacks cancerous
growths
12.2 Notes – The Immune System
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antigens – sends the immune system into
action
antibodies – proteins that attach to antigens,
keeping them from harming the body
immunity – the body’s ability to resist the
pathogens that cause a particular disease
vaccine – (a shot) a preparation of dead or
weakened pathogens that is injected into the
body to cause the immune system to produce
antibodies