Download Immune System

Lymphatic System

Lymphatic system:
network of lymphatic
vessels and organs


Returns tissue fluid
to the circulatory
system
Fights infections
Lymphatic System

Lymph nodes key sites for fighting
infection

Packed with lymphocytes and macrophages
Immune System: Nonspecific
Defense

Body’s first lines of defense against
infection


skin, mucous membrane, enzymes, tears,
acids, proteins, macrophages
Nonspecific: do not distinguish one
infectious microbe from another
Immune System: Nonspecific
Defense

Macrophages wander interstitial fluid

“eat” any bacteria and virus-infected cells
they encounter
Immune System: Specific Defense


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Specific Response: immune systems
responds to foreign molecules - antigens
Pathogen: foreign invader
Antigen: piece of pathogen that our white
blood cells recognize
Immune System: Specific Defense

Two kinds of
lymphocytes



B cells - secrete
antibodies, wander
fluid
T cells attack cells
infected with
pathogens
Antigen enters the
body, it activates only
lymphocytes with
matching receptors
Immune System: Primary and
Secondary Response
Immune System: B Cells
Primary vs Secondary Response

B cell differentiates into:


Effector cell (plasma cell) – makes antibodies
Memory cell: remembers for next time
Immune System:
Active vs Passive Immunity

Active: when you’re
cells made antibodies
/ longterm

vaccination

Passive: when given
antibodies


No memory cells made
Short term, ex breast
feeding
Immune System: T Cells


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T cells : when cells have been attacked
Helper T cells and killer T cells
Helper T cells


recognize attacked cell and divide
Killer T cells

destroy infected cell so virus can’t multiply
Immune System:
Disorders

Autoimmune diseases

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Immunodeficiency diseases


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System turns against the body’s own molecules
Immune system compromised
Ex. AIDS virus attacks helper T Cells
Physical and emotional stress may weaken the
immune system