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Immunity
Chapter 40 Section 2
Lymphatic System
Types of White Blood Cells
• Formed in Bone Marrow, Thymus,
spleen, and / or lymph system
–Lymphocytes (B and T Cells)
–Monocytes
–Neutrophils
–Basophils: secret histamines
–Eosinophils
White Blood Cells
• Neutrophils
–phagocytic cells
–Damaged cells release chemicals
that neutrophils recognize
(chemotaxis)
–Use phagocytosis to destroy
invading cells
–Life span: few days
White Blood Cells
• Macrophages (Monocytes)
–Largest phagocytic cells
–Effective and long – lived
–Engulfs invading cell and merges
it with a lysosome. Needs helper
T cells.
–Some migrate and others are
fixed.
Other White Blood Cells
• Eosinophils
–Attacks larger parasitic invaders
–Limited phagocytic activity
–Attack by sending destructive
enzymes to the cell wall of
invader.
NK Cells
• Natural Killer Cells
–Not phagocytic
–Destroys virus infected cells and
abnormal body cells
–Causes cells to lyse by breaking
down the membrane.
Antimicrobrial Proteins
• 20 serum protiens known as
compliment system
• Leads to lysis of microbes
• Other protiens include interferons:
Inhibit viruses from invading
neighboring cells interupting
replication (above 2 interferons)
The Inflammatory Response
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Localized
Triggered by tissue damage
Blood supply to area increases
Chemical signals are released
The Inflammatory Response
• Basophils and mast cells secret
histamine
• Prostaglandins released
• Neutrophils, then Macrophages
arrive
The Inflammatory Response
Self VS. Nonself
• Immune system can recognize
antigens of organism as well as
foreign cells.
• During development if a lymphocyte
has receptors for naturally occuring
molecules, the cell will be destroyed.
Self VS. Nonself
• Only lymphocytes that recognize
forgein antigens will be left.
Leading to specific immunity.
• Failure to do this leads to
autoimmune disease.
Specific Immunity: 3rd line of Defense
• B lymphocytes and T lymphocytes:
–Circulate through blood and
lymph system
–Concentrated in the spleen,
lymph nodes, and lymph tissues
Specific Immunity: 3rd line of Defense
• B lymphocytes – mature in bone
marrow
• T lymphocytes – begin in bone
marrow and mature in thymus
Specific Immunity: 3rd line of Defense
–Respond to specific microbes by
their antigens (chemical markers
on invading materials)
–B cells secrete antibody proteins
–T cells destroy infected cells
Specific Immunity: 3rd line of Defense
• Both B and T cells can form:
–Effector Cells – short lived cells
to combat same antigen
–Memory Cells – long lived cells
containing receptors for same
antigen
Primary Immune Response
• The first time the body is exposed
to a specific antigen.
• 10-17 days are required from initial
exposure until antigen specific
lymphocytes can be produced.
Primary Immune Response
• While effector B cells and T cells
are developed the individual may
become ill.
• Memory Clone cells of both will
form.
Secondary Immune Response
• When the same individual is
exposed to the same antigen at a
later date.
• Response is faster - 2 to 7 days.
• Greater magnitude and more
prolonged
• Antibodies have a greater affinity
for the antigen.
• Immunological memory.
Time of Antibody Production
Humoral Immunity
• B cell activation results from the
production of antibodies that
circulate in the blood plasma and
lymph fluids.
• Defenses against: free bacteria,
toxins, and viruses in body fluids.
Humoral Immunity
• Antigen specific B cell binds to
antigen
• B cells grow and divide into:
plasma cells which secret
antibodies and memory B cells.
With aid of Helper T cells.
Humoral Immunity
• Antibodies released in the blood
stream destroy the pathogen.
• Once defeated plasma cells die
out and antibodies are no
longer produced.
Humoral Immunity
• Antibodies attach to membrane /
cell wall of pathogen
• Can cause clumping of pathogen
(agglutination) or neutrilization
• Macrophage will consume by
phagocytosis.
• OR
Hummoral Immunity
• Antibodies attach to membrane /
cell wall of pathogen
• Compliment protiens attach to two
antibodies
• Compliment proteins are activated
and attach to membrane forming a
pore.
• Causes cell to lyse
Humoral Immunity
Cell Mediated Immunity
• Depends on the action of T Cells
• Defends against: viruses and
bacteria in infected cells, fungi,
protists, and parasitic worms. As
well as transplanted tissue and and
cancer cells.
Cell Mediated Immunity
• Types of T lymphocytes:
–Killer (cytotoxic): Lysis infected
cells
–Helper : increase responses of B
lymphocytes and killer T
lymphocytes.
–Suppressor: decrease responses
of B lymphocytes and killer T
lymphocytes
Cell Mediated Immunity
• Helper T Cells bind to a specific
receptor site on a macrophage.
• A chemical message sent for the
production of Killer T Cells and the
plasma cells of hummoral immunity.
Cell Mediated Immunity
• Killer T cells attack
infectes/abnormal cells or form
memory T cells
• Killer T cells bind to infected /
abnormal cell to a specific receptor.
Cell Mediated Immunity
• A specilized protien (perforin) is
discharged from Killer T cell.
• Proteins form pores in the cell
membrane.
• Water and ions enter through
pores.
• Cell lyses
Cell Mediated Immunity
–Suppressor T Cells:
–Release chemicals that inhibit the
active killer T cells.
–They also inhibit the helper T
cells.
–Memory T cells last, other T cells
die.
Both hummoral and cell
mediated immunity occur at
the same time.
Immunity Overview