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
• 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