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