Learning Objectives
Describe the structure and function of lymphatic cells, tissues and organs
List the body’s nonspecific defenses and describe the components and mechanisms of each
Define specific resistance and distinguish between cell-mediated immunity and antibody mediated immunity
Learning Objectives
Discuss the role of the T cell, B cell and antibodies in specific immunity
Describe the origin, development, activation and regulation of normal resistance to disease
Discuss the effects of stress and aging on the immune system
SECTION 22-1 An Overview of the Lymphatic System and Immunity
lymphatic system
The lymphatic system
Contains cells, tissues, and organs responsible for defending the body
Lymphocytes resist infection and disease by responding to
Invading pathogens such as bacteria or viruses
Abnormal body cells such as cancer cells
Foreign proteins such as toxins
Figure 22.1 The Components of the Lymphatic System
SECTION 22-2 Organization of the Lymphatic System
The lymphatic system consists of
Lymph
Lymphatic vessels
Lymphoid tissues and organs
Lymphocytes and supporting phagocytic cells
Functions of lymphatic system
Primary function is production, maintenance, and distribution of lymphocytes
Lymphocytes must:
Detect where problems exist
Be able to reach the site of injury or infection
Lymphatic vessels include
Lymphatic capillaries
Small lymphatic vessels
Major lymph-collecting vessels
Figure 22.2 Lymphatic Capillaries
Figure 22.3 Lymphatic Vessels and Valves
Major lymph-collecting vessels
Superficial and deep lymphatics
Thoracic duct
Cisterna chyli
Right lymphatic duct
Figure 22.4 The Relationship between the Lymphatic Ducts and the Venous System
Figure 22.4 The Relationship between the Lymphatic Ducts and the Venous System
Figure 22.4 The Relationship between the Lymphatic Ducts and the Venous System
Lymphocytes
Three classes of lymphocytes
T (thymus dependent) cells
B (bone marrow-derived) cells
NK (natural killer) cells
Lymphocyte production (lymphopoiesis)
Involves bone marrow, thymus, and peripheral lymphoid tissue
B cells and NK cells mature in bone marrow
T cells mature in the thymus
Figure 22.5 The Derivation and Distribution of Lymphocytes
Lymphoid tissue
Connective tissue dominated by lymphocytes
Lymphoid nodules
Lymphocytes densely packed in areolar tissue
Found in the respiratory, digestive, and urinary tracts
MALT (mucosa-associated lymphoid tissue)
Collection of lymphoid tissues linked with the digestive system
Figure 22.6 Lymphoid Nodules
Lymphoid organs
Lymph nodes – function in the purification of lymph
Afferent lymphatics – carry lymph to nodes
Efferent lymphatics – carry lymph from nodes
Deep cortex dominated by T cells
Outer cortex and medulla contains B cells
Figure 22.7 The Structure of a Lymph Node
