The Lymphatic System and Body Defenses 12 The Lymphatic System and Body Defenses

The Lymphatic System and Body Defenses I. Introduction– Functions Transports: White Blood Cells: Body Defences II. Parts Lymph Fluid Lymphatic Vessels Lymph Nodes Lymphoid Organs Have WBC

III. Physiology– Body Defences A. Introduction-- 2 Systems or Processes Innate, nonspecific General Defense: 1st and 2nd lines of Defense involve non-specific processes: Adaptive, specific Specific Defence: Immunity = 3rd Line of Defense involves lymphocytes

Figure 12.6

B. Innate (Nonspecific) Body Defences 1. FIRST LINE OF DEFENCE. a B. Innate (Nonspecific) Body Defences 1. FIRST LINE OF DEFENCE a. Surface Membrane Barriers i) Skin and mucous membranes Physical barrier Tissues Protective secretions pH of the skin: Sebum: Vaginal secretions:

b. Internal Membranes (Serous) i) Stomach mucosa ii) Saliva and lacrimal fluid: iii) Digestive & Respiratory System Mucus:

2. SECOND LINE OF DEFENCE: Cells & Chemicals NK Natural killer (NK) cells - Not specific Lyse Cancer ii) Virus-infected cells iii) Release perforin: Bacteria

b. Phagocytes Neutrophils and Monocytes Phagocytosis: Lysosomes:

Figure 12.9a

Second Line of Defense … c. Inflammatory response i) Injured cells: ii) Four indicators: Redness Heat Swelling Pain

iii) Process: Neutrophils migrate: Diapedesis: Phagocytosis: Blood Vessels Leaky-- Fibrinogen Basophils

iv) Functions: Prevents spread of damaging agents Disposes of cell debris and pathogens

iv) Functions: Prevents spread of damaging agents Disposes of cell debris and pathogens d. Fever = Abnormally high body temperature Cause: Pyrogens secreted by WBC Function: (1) Inhibit the release of iron and zinc needed by bacteria (2)Increases the speed of tissue repair

C. THIRD LINE OF DEFENCE = Adaptive/Specific Defence System 1. INTRODUCTION a. Produced by cells and chemicals b. Immune response is the immune system’s response to: c. Immunity occurs after: d. Antibodies: 14

e. Cells of the adaptive defence system Lymphocytes respond to specific antigens B lymphocytes (B cells) T lymphocytes (T cells) Macrophages help lymphocytes 15

2. Role of T cells Coordinate Immune Responses

3. Antibody-Mediated Immune Response Role of B Cells Antigen a. Primary Response Body finds the specific B lymphocytes with the correct antibodies that bind to a specific antigen B lymphocytes are cloned Antibodies released to destroy antigen Activity lasts for 4 or 5 days Primary Response (initial encounter with antigen) Receptor 1-2 weeks Proliferation to form a clone Activated B cells 17

Some B cells become long-lived memory cells b. Secondary responses: when same pathogen encountered for 2nd time Memory cells become active Rapid response: hours to 1or 2 days Stronger and longer lasting Secondary Response (can be years later) Subsequent challenge by same antigen results in more rapid response Clone of cells identical to ancestral cells Plasma cells Memory B cells Secreted antibody molecules 18

4. Result of Secondary Response Is Active Immunity a. Naturally acquired during 1st response to specific bacteria and viruses b. Vaccines: Artificially acquired Vaccine exposes immune system to pathogen parts with the antigens First Humoral response is initiated Memory B cells are saved If pathogen ever encountered do 2nd response 19

Secreted antibody molecules Figure 12.12 Vaccine Primary Response (initial encounter with antigen) Vaccine binding to a receptor on a specific B cell (B cells with Proliferation to form a clone Activated B cells Plasma cells Memory B cell Secreted antibody molecules Secondary Response (can be years later) Subsequent challenge by the real pathogen results in more rapid response Clone of cells identical to ancestral cells Plasma cells Secreted antibody molecules Memory B cells Secreted antibody molecules Figure 12.12 20

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