Transcript Immune System

Warm Up:
• What is homeostasis?
• Recall: Homeostasis is the
regulation of an organism’s internal
environment to maintain conditions
needed for life
When homeostasis is disrupted
disease can occur
Immune System
What is a
pathogen?
• Cause of
infectious
disease
Types of pathogens
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Virus
Bacteria
Fungus
Parasites
Protists
These are microbes:
microscopic organisms
What is Cancer?
• Characterized by
abnormal and
uncontrolled cell
growth
Why is cancer an example of the
body not maintaining homeostasis?
• Normally the body controls beginning and
end of the cell cycle
•If control is lost, abnormal or uncontrolled
cell growth can lead to tumors
The Immune System
• Mechanisms in an
organism that protects
body against
disease
Antigen
Substance foreign to the body that
causes an immune response
Body’s 1st Line of Defenses
Barriers
-Skin barrier
-Chemical barriers (saliva, tears,
nasal secretions)
-Hydrochloric acid in
stomach
Body’s 2nd Line of Defenses
Non-Specific Response
-White blood cell
use engulf pathogen
Body’s 3rd Line of Defenses
Specific Response
involves lymphatic system which filters
lymph and blood destroying foreign
microorganisms
Includes B cell and T cell response
Antibodies
• Proteins produced by
B lymphocytes (B cells) that specifically
react with a foreign antigen
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T cells
• Helper T cells activate antibody production
in B cells and activates cytotoxic T cells
• Cytotoxic T cells destroy pathogens and
release chemicals
White blood cells
• Some WBCs mark pathogens for
destruction while others engulf microbes
during an immune response
• And yet others produce antibodies
Why do people rarely get the same
disease twice?
• Memory cells reduce the likelihood of
developing the same disease twice
Vaccine
• Dead or weakened form of a virus used to
stimulate an immune response
Immunity
• 2 Types
– Inborn Immunity: immunity to disease at birth
– Acquired Immunity: develops during lifetime
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Acquired Immunity
Passive Immunity
Active Immunity
Antibodies made by
other people are
transferred or injected
into the body
(temporary)
Ex. Between mother and
child
Immune system
exposed to the disease
antigens and memory
cells are produced
Ex. Vaccination
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Allergies
• Reactions to usually harmless
environmental antigens
• Mast cells release histamines
• Causes a localized inflammatory response
– Swollen, itchy eyes, stuffy nose, sneezing
•Pollen, dust, dust
mites, food
AIDS
• Human Immunodeficiency Virus
• Attacks white blood cells (CD4)
• Weakens patient’s immune system