PowerPoint® Lecture Slides prepared by Jason LaPres C h a p t e r 23 The Lymphoid System PowerPoint® Lecture Slides prepared by Jason LaPres North Harris College Houston, Texas Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Introduction The lymphoid system Lymphatic vessels Lymph (fluid connective tissue) Lymphoid tissues Lymphoid organs Plays central role in body’s defenses against viruses, bacteria, and other microorganisms Lymphatic vessels originate in peripheral tissues and deliver lymph to the venous system. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

An Overview of the Lymphoid System Lymph consists of: Interstitial fluid, which resembles blood plasma, but with a lower concentration of proteins Lymphocytes, cells responsible for the immune response Macrophages of various types Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

An Overview of the Lymphoid System Primary functions of the lymphoid system: Produce, maintain, and distribute lymphocytes Maintain normal blood volume and eliminate local variations in the chemical composition of the interstitial fluid Provide an alternative route for the transport of hormones, nutrients, and waste products Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

An Overview of the Lymphoid System Figure 23.1 Lymphoid System Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Lymphatic capillaries Lymphatic vessels (or lymphatics) carry lymph from peripheral tissues to the venous system. Lymphatic capillaries (or terminal lymphatics) form a complex network within peripheral tissues. Lymphatics contain internal valves that prevent backflow of lymph/ Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Two sets of lymphatic vessels: Superficial lymphatic vessels travel with superficial veins The subcutaneous layer next to the skin The loose connective tissues of the mucous membranes The loose connective tissues of the serous membranes Deep lymphatic vessels are large lymphatic vessels that accompany the deep arteries and veins. Collect lymph from skeletal muscles and other organs of the neck, limbs, and trunk, as well as visceral organs in the thoracic and abdominopelvic cavities Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Figure 23.2a Lymphatic Capillaries: (a) Association of Blood Capillaries, Tissue, and Lymphatic Capillaries Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Figure 23.2b Lymphatic Capillaries: (b) Sectional View Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Figure 23.3 Lymphatic Vessels and Valves Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Figure 23.4 Lymphatic Ducts and Lymphatic Drainage Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Structure of Lymphatic Vessels Figure 23.5 Major Lymphatic Vessels of the Trunk Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphocytes Lymphocytes are the primary cells of the Lymphoid system, and they are responsible for specific immunity. They respond to the presence of Invading organisms, such as bacteria and viruses Abnormal body cells, such as virus-infected cells or cancer cells Foreign proteins, such as the toxins released by some bacteria Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphocytes Three different classes of lymphocytes in the blood: T cells (thymus dependent) Cytotoxic T cells Helper T cells Suppressor T cells Memory T cells B cells (bone marrow derived) Plasma cells Memory B cells NK cells (natural killer) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphocytes Figure 23.6 Lymphocytes and the Immune Response Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphocytes Figure 23.7 Derivation and Distribution of Lymphocytes Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Tissues Any tissue containing an abundance of lymphocytes Diffuse lymphoid tissues—loosely packed lymphocytes within connective tissue Lymphoid nodules—densely packed lymphocytes within loose connective tissue Tonsils Aggregated lymphoid nodules (Peyer’s patches) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Tissues Figure 23.8a Histology of Lymphoid Tissues: (a) Aggregated Lymphoid Nodule (Intestinal Tract) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Tissues Figure 23.8b Histology of Lymphoid: (b) Pharyngeal Tonsil (Respiratory Tract) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Lymphoid tissues that are separated from surrounding tissues by a capsule Lymph nodes Thymus Spleen Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.9 Structure of a Lymph Node Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.10 Lymphatic Drainage of the Head and Neck Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.11a Lymphatic Drainage of the Upper Limb: (a) Male, Anterior View Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.11b Lymphatic Drainage of the Upper Limb: (b) Female, Anterior View Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.12 Lymphatic Drainage of the Lower Limb Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.13 A Pelvic Lymphangiogram Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.14a, b Lymphatic Drainage of the Inguinal Region: (a) Dissection of the Upper Right Inguinal Region in a Male (b) Inguinal Lymph Nodes and Vessels Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.15 Lymph Nodes in the Large Intestine and Associated Mesenteries Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.16 Anatomy and Histological Organization of the Thymus Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.17 Anatomy and Histological Organization of the Spleen Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Lymphoid Organs Figure 23.18 Jan’s X-Ray Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Aging and the Lymphoid System With advancing age, the lymphoid system becomes less effective at combating disease. T cells become less responsive to antigens. The number of helper T cells is reduced. B cells are less responsive. Antibody levels do not rise as quickly after antigen exposure. The net result is an increased susceptibility to viral and bacterial infection, and cancer. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings