Lymphatic System and Immunity Chapter 14 PDF

Lymphatic System and Immunity Chapter 14 Copyright © 2016 by Elsevier Inc. All rights reserved. 1  Learning Objectives Lesson 14.1: Lymphatic System and Immunity 1. Describe the generalized functions of the lymphatic system and...

Lymphatic System and Immunity Chapter 14 Copyright © 2016 by Elsevier Inc. All rights reserved. 1  Learning Objectives Lesson 14.1: Lymphatic System and Immunity 1. Describe the generalized functions of the lymphatic system and list the primary lymphatic structures. 2. Discuss the immune system, and compare nonspecific and specific immunity, natural and artificial immunity, and active and passive immunity. 3. Discuss the major types of immune system molecules and indicate how antibodies and complement proteins function. Copyright © 2016 by Elsevier Inc. All rights reserved. 2  Learning Objectives Lesson 14.1: Lymphatic System and Immunity (Cont.) 4. Discuss the development and functions of B and T cells, and compare and contrast humoral and cell-mediated immunity. Copyright © 2016 by Elsevier Inc. All rights reserved. 3  Lymphatic System  Organization of the lymphatic system  Lymph  Fluid in the tissue spaces that carries protein molecules and other substances back to the blood  Lymphatic capillaries: Tiny blind-ended tubes distributed in tissue spaces (Figure 14-2)  Lymphatic capillaries  Permit only one-way movement of lymph  Microscopic in size  Sheets consisting of single cell layer of simple squamous epithelium  Poor “fit” between adjacent cells results in porous walls Copyright © 2016 by Elsevier Inc. All rights reserved. 4  Lymphatic System (Cont.)  Lymphatic vessels  Right lymphatic duct Drains lymph from the right upper extremity and right side of head, neck, and upper torso  Thoracic duct Largest lymphatic vessel Has an enlarged pouch along its course, called cisterna chyli Drains lymph from about three-fourths of the body Copyright © 2016 by Elsevier Inc. All rights reserved. 5 Lymphatic System (Cont.) Drake RL et al: Gray’s anatomy for students, ed 3, Philadelphia, 2015, Churchill-Livingstone. Copyright © 2016 by Elsevier Inc. All rights reserved. 6 Role of Lymphatic System in Fluid Homeostasis Copyright © 2016 by Elsevier Inc. All rights reserved. 7  Lymphatic System (Cont.)  Lymph nodes (Figure 14-3)  Lymph travels from its origin toward the thoracic or right lymphatic ducts and then to the venous blood; filtered by passing through lymph nodes  Located in clusters along the pathway of lymphatic vessels  Lymphoid tissue Mass of lymphocytes and related cells inside a lymphoid organ Provides immune function and development of immune cells  Lymph nodes and other lymphoid organs have functions that include defense and WBC formation Copyright © 2016 by Elsevier Inc. All rights reserved. 8  Lymphatic System (Cont.)  Lymph nodes  Biological filtration Flow of lymph to node via several afferent lymphatic vessels and drained from node by a single efferent lymph vessel The breast has a uniquely extensive network of lymphatic drainage (Figure 14-4) Copyright © 2016 by Elsevier Inc. All rights reserved. 9 Lymphatic Node Function Copyright © 2016 by Elsevier Inc. All rights reserved. 10 Lymphatic Drainage of the Breast From Ball JW, Dains JE, Flynn JA, et al: Seidel’s guide to physical examination, ed 8, St Louis, 2015, Mosby. Copyright © 2016 by Elsevier Inc. All rights reserved. 11  Lymphatic System (Cont.)  Thymus  Small lymphoid tissue organ located in mediastinum  Total weight of 35 to 40 grams; a little more than an ounce  Plays a vital and central role in immunity  Produces T lymphocytes, or T cells  Secretes hormones called thymosins, which influence T-cell development  Thymus tissue gradually replaced by fat and connective tissue (during adulthood) in a process called involution Copyright © 2016 by Elsevier Inc. All rights reserved. 12  Lymphatic System (Cont.)  Tonsils  Composed of three masses of lymphoid tissue around the openings of the mouth and throat Palatine tonsils (“the tonsils”) Pharyngeal tonsils (also known as adenoids) Lingual tonsils  Subject to chronic infection  Enlargement of pharyngeal tonsils may impair breathing Copyright © 2016 by Elsevier Inc. All rights reserved. 13 Location of the Tonsils Copyright © 2016 by Elsevier Inc. All rights reserved. 14  Lymphatic System (Cont.)  Spleen  Largest lymphoid organ in the body  Located in upper left quadrant of abdomen lateral to the stomach  Often injured by trauma to abdomen  Surgical removal called splenectomy  Functions include phagocytosis of bacteria and old RBCs; acts as a blood reservoir (500 mL) Copyright © 2016 by Elsevier Inc. All rights reserved. 15  Immune System  Functions of the immune system  Protects body from pathological bacteria, foreign tissue cells, and cancerous cells  Made up of defensive cells and molecules  Nonspecific immunity (Tables 14-1 and 14-2)  Often called innate immunity because it does not require prior exposure to an antigen  Inflammatory response: Cytokines (chemical mediators) attract immune cells to site of injury, increases local blood flow, increases vascular permeability; promotes movement of WBCs to site of injury or infection (Figure 14-6) Copyright © 2016 by Elsevier Inc. All rights reserved. 16 Nonspecific and Specific Immunity Copyright © 2016 by Elsevier Inc. All rights reserved. 17 Mechanisms of Nonspecific Defense Copyright © 2016 by Elsevier Inc. All rights reserved. 18 Inflammatory Response Copyright © 2016 by Elsevier Inc. All rights reserved. 19  Immune System (Cont.)  Specific immunity (Tables 14-1 and 14-3)  Often called adaptive immunity because of the ability to recognize, respond to, and remember harmful substances or bacteria  Natural immunity: Exposure to causative agent is not deliberate Active: Active disease produces immunity Passive: Immunity passes from mother to fetus through placenta or from mother to child through mother’s milk Copyright © 2016 by Elsevier Inc. All rights reserved. 20  Immune System (Cont.)  Specific immunity  Artificial immunity: Exposure to causative agent is deliberate Active: Vaccination results in activation of immune system Passive: Protective material developed in another individual’s immune system and given to previously nonimmune individual Copyright © 2016 by Elsevier Inc. All rights reserved. 21 Types of Specific Immunity Copyright © 2016 by Elsevier Inc. All rights reserved. 22  Immune System Molecules  Cytokines  Chemicals released from cells to act as direct agents of innate, nonspecific immunity  Antibodies  Protein compounds with specific combining sites  Combining sites attach antibodies to specific antigens (foreign proteins), forming an antigen-antibody complex; called humoral immunity, or antibody-mediated immunity (Figure 14-7)  Antigen-antibody complexes may: Neutralize toxins Clump or agglutinate enemy cells Promote phagocytosis Activates complement proteins Copyright © 2016 by Elsevier Inc. All rights reserved. 23 Antibody Function Copyright © 2016 by Elsevier Inc. All rights reserved. 24  Immune System Molecules (Cont.)  Complement proteins  Group of protein enzymes normally present in an inactive state in blood  May be activated by triggers; process is rapid-fire cascade called complement cascade Important mechanism of action for antibodies Causes cell lysis by permitting entry of water through a defect created in the plasma membrane (Figure 14-8)  Serve other roles in immune system Attracting immune cells to a site of infection Activating immune cells Marking foreign cells for destruction Increasing permeability of blood vessels  Play vital role in producing the inflammatory response Copyright © 2016 by Elsevier Inc. All rights reserved. 25 Complement Cascade Copyright © 2016 by Elsevier Inc. All rights reserved. 26  Immune System Cells  Phagocytes  Ingest and destroy foreign cells or other harmful substances via phagocytosis (Figure 14-9)  Neutrophils: Short-lived phagocytic cells  Monocytes: Develop into phagocytic macrophages and migrate to tissues  Dendritic cells (DCs): Often found at or near external surfaces  Macrophages and DCs act as antigen-presenting cells (APCs) by displaying ingested antigens on their outer surface to trigger specific immune cells Copyright © 2016 by Elsevier Inc. All rights reserved. 27 Phagocytosis of Bacteria Copyright © 2016 by Elsevier Inc. All rights reserved. 28  Immune System Cells (Cont.)  Lymphocytes  Most numerous of immune system cells  Development of B cells: Primitive stem cells migrate from bone marrow and go through two stages of development (Figure 14-12) First stage: Stem cells develop into immature B cells  Takes place in the liver and bone marrow before birth and in the bone marrow only in adults  B cells are small lymphocytes with antibody molecules (which they have synthesized) in their plasma membranes  After they mature, inactive B cells migrate chiefly to lymph nodes Copyright © 2016 by Elsevier Inc. All rights reserved. 29 B-Cell Development Copyright © 2016 by Elsevier Inc. All rights reserved. 30  Immune System Cells (Cont.)  Lymphocytes  Development of B cells Second stage: Inactive B cell develops into activated B cell  Initiated by inactive B cell’s contact with antigens, which bind to its surface antibodies, plus cytokines (signal chemicals) from T cells  Activated B cell, by dividing repeatedly, forms two clones of cells – plasma (effector) cells and memory cells  Plasma cells secrete antibodies into blood; memory cells are stored in lymph nodes  If subsequent exposure to antigen that activated B cell occurs, memory cells become plasma cells and secrete antibodies Copyright © 2016 by Elsevier Inc. All rights reserved. 31  Immune System Cells (Cont.)  Lymphocytes  Function of B cells: Indirectly, B cells produce humoral immunity Activated B cells develop into plasma cells Plasma cells secrete antibodies into the blood Circulating antibodies produce humoral immunity (Figure 14-12)  Development of T cells: Stem cells from bone marrow migrate to thymus gland (Figure 14-13) First stage: Stem cells develop into T cells  Occurs in thymus during few months before and after birth  T cells migrate chiefly to lymph nodes Second stage: T cells develop into activated T cells  Occurs when, and if, antigen binds to T cell’s surface proteins and a chemical signal is received from another T cell Copyright © 2016 by Elsevier Inc. All rights reserved. 32 T-Cell Development Copyright © 2016 by Elsevier Inc. All rights reserved. 33  Immune System Cells (Cont.)  Lymphocytes  Function of T cells: Produce cell-mediated immunity (Figures 14-13 and 14-14) Cytotoxic T cells  Kill infected or tumor cells by releasing a substance that poisons infected or tumor cells Helper T cells  Release chemicals that attract and activate macrophages to kill cells by phagocytosis  Produce chemicals that help activate B cells Regulatory T cells  Release chemicals to suppress immune responses Copyright © 2016 by Elsevier Inc. All rights reserved. 34 T-Cell Function Copyright © 2016 by Elsevier Inc. All rights reserved. 35  Questions? Copyright © 2016 by Elsevier Inc. All rights reserved. 36