chapter 24 ~ the immune system. animal immune system
TRANSCRIPT
Chapter 24 ~ The Immune System
Animal immune system
Phagocytic and Natural Killer Cells• Neutrophils
60-70% WBCs; engulf and destroy microbes at infected tissue
• Macrophages
enzymatically destroy microbes
• Natural killer (NK) cells
destroy virus-infected body cells & abnormal cells
The Inflammatory Response • Histamine triggers dilation and permeability of capallarie
• Chemokines: attract phagocytes• Leukocyte-released molecules increase body temperature
The lymphatic system• Involved in innate and acquired immunity.
• Functions are to return fluid from the interstitial spaces to the circulatory system, and to combat infection
Acquired Immunity• Antigen: a foreign molecule that elicits a
response by lymphocytes (virus, bacteria, fungus, protozoa, parasitic worms)
• Antibodies: antigen-binding immunoglobulin, produced by B cells.
• Vaccine : introduction of a harmless variant to stimulate immune system.
• Active immunity: immune system produces antibodies.
• Passive immunity: receiving pre-made antibodies.
Lymphocyte’s dual defense• Types of lymphocytes: B cells develop in
bone marrow, T cells develop in the thymus.
• Humoral immune response is the production of antibodies by B cells. Defend against bacteria and viruses found in body fluids.
• Cell mediated immune response is the production of defensive cells by T cells- phagocytes.
Clonal selection
• Clonal selection: antigen-driven cloning of lymphocytes
• Effector cells: short-lived cells that combat the antigen that secrete antibodies
• Memory cells: long-lived cells that bear receptors for the antigen
Immune Responses• Primary immune response: lymphocyte proliferation and
differentiation the 1st time the body is exposed to an antigen
• Plasma cells: antibody-producing effector B-cells
• Secondary immune response: immune response if the individual
is exposed to the same antigen at some later time~ Immunological memory
Antibodies (Ig)
• Two functions of antibodies: recognize and bind to antigens, and then to neutralize that antigen.
• The antigen binding site is shape specific for antigen.
• Antibodies mark specific antigens for destruction.
Helper T’s role in humoral and cell mediated responses
• Helper T cells release proteins that activate both cytotoxic T cells and B cells
Cytotoxic T cells destroy infected body cells
Summary of acquired immunity• Humoral immunity• B cell activation• Production of antibodies• Defend against bacteria,
toxins, and viruses free in the lymph and blood plasma
• Cell-mediated immunity• T cell activation• Binds to and/or lyses cells• Defend against cells infected
with bacteria, viruses, fungi, protozoa, and parasites; nonself interaction