Transcript Bio Immune System 2013

Immune System
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What It’s All About – the BASICS
• Defend the body against pathogens
• Recognize self from non-self
• Specific and Non-specific
“Bottom line”:
Fight infection through the production of cells
that inactivate foreign substances/cells
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Protection
• Pathogens
– Infectious disease
– Toxic
– Reproduce in the host
– GERMS
• Koch’s postulate
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4 ways of getting sick
• Contact an infected person directly
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4 ways of getting sick
• Contact an infected person INdirectly
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4 ways of getting sick
• Eat infected food or drink infected water
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4 ways of getting sick
• Get bitten by an infected animal
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Bubonic Plague
Bubonic plague is an infectious disease, circulating mainly among small rodents
and their fleas. Without treatment, the bubonic plague kills about two thirds of
infected humans within 4 days. Swollen lymph glands are typical symptoms of the
plague. During the 14th century, 25 million people in Europe were belived to have
died (around 40% of the entire population).
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Immune System Anatomy
• Lymphatic System
–Lymph (fluid with WBCs)
–Lymph nodes (store WBCs)
–Tonsils, thymus, spleen, appendix, red
bone marrow, adenoids
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Line up the Troops
• First line of defense is non-specific
– Blocks anything from entering body system
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First Line of Defense Examples
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Skin: wall that blocks pathogens
Sweat: acidic, salty, contains enzymes
Mucus: coats openings to body
Tears: wash out pathogens entering eye
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If that didn’t work….
• Second line of defense: Inflammatory Response
When the pathogen enters the body
– Injured cells release HISTAMINE
• Capillaries expand so blood flow increases
• Fluid leaks out into space between cells
– Swelling, redness, pain, heat
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SPECIFIC DEFENSE
IMMUNE RESPONSE
– Specific for pathogen
– Most effective if you’ve been infected
before
– Through entire body
– Triggered by substance in pathogen =
antigen
– Can be defense in body fluids (humoral) OR
defense against abnormal cells or
pathogens (cell-mediated)
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Cells Involved
White Blood cells = LEUKOCYTES
They are made in the bone marrow
Some develop in bone marrow, others in the
thymus
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Cells Specifics
Non-specific:
Phagocytes: engulf (eat) and
digest pathogens
Macrophages are the biggest
Specific:
Lymphocytes: B-cells and Tcells
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Humoral Immunity –
Immunity against pathogens in body fluids
 Some B cells recognize specific pathogen
• B cells mature in Bone marrow
• Antibodies from B-cells
• Some B cells remember specific antigens &
will produce antibodies whenever the
pathogen reappears (memory cells)
• Antibodies:
– Attach to antigen and attract macrophages
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10 to 17 days for full response
B cell immune responseY
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release antibodies
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recognition
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plasma cells
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captured
invaders
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“reserves”
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memory cells
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B cells + antibodies
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invader
(foreign antigen)
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tested by B cells
(in blood & lymph)
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clone
1000s of clone cells
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Lymphocytes: B-cell
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Cell-Mediated Immunity
• Cells directly attack and destroy Ag (antigen)
– Cancer cells, infected body cells, invading cells
• T cells involved
– Born in bone marrow but mature in Thymus
– 3 types: killer, helper, suppressor
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T cells
• Killer T cells
– Attack Ag (puncture cell membrane)
• Helper T cells (aka T4)
– Stimulate Killer Ts to divide, stimulate B cells to
divide and release Antibodies
• Suppressor T cells
– Stop the activity of other T cells
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T cell response
infected cell
killer
T cell
helper
T cell
or
activated
macrophage
activate
killer T cells
helper
T cell
helper
T cell
stimulate
B cells &
antibodies
helper
T cell
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helper
T cell
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Lymphocytes From Stem Cells
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Lymphocytes: T-cell
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Memory Cells
Primary response: new pathogen,
new response (5-10 days until max production
of B and T cells)
Secondary Response: same pathogen,
old response (1-2 days, so you don’t even get
sick!)
Memory cells can last your entire life!!
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Vaccinations
• Immune system exposed
to harmless version of pathogen
– triggers active immunity
– stimulates immune system to produce
antibodies to invader
– rapid response if
future exposure
• Most successful
against viral diseases
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Immune response
pathogen invasion
antigen
exposure
skin
free antigens in blood
humoral response
memory
B cells
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Y antibodies
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macrophages
(APC)
cellular response
T cells
memory
T cells
cytotoxic
T cells
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plasma
B cells
antigens on infected cells
helper
T cells
B cells
skin
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HIV and AIDS
• HIV attacks T4 cells (Helper T cells)
• Body can’t defend against any Ags!
• Known as an STD: transported in semen, blood,
breast milk
• Once T4 count is so low that body can’t fight
disease, we say the person has AIDS
• Takes about 10 years to develop AIDS
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AIDS Infection
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Huge Outbreak in Africa
African Children Orphaned by AIDS
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Allergies
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Allergies
• Histamine released even though
antigen is harmless
• If blood vessels dilate too much:
ANAPHYLACTIC SHOCK
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Autoimmune Disorders
• Immune system attack SELF cells
• Multiple Sclerosis: T cells destroy nerve cells
• Maybe Type 1 Diabetes is attack on pancreas
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Multiple Sclerosis
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