Exercise 38 The Lymphatic System and Immune Response

Exercise 38 The Lymphatic System and Immune Response

Lymphatic System Lymphatic vessels ¢ Lymphatic tissues l Tonsils ¢ Primary lymphatic organs l Thymus and Bone marrow ¢ Secondary lymphatic organs l Lymph nodes, spleen ¢

Lymphatic System

Lymphatic System Lymph l Fluid lost from the capillaries l Edema ¢ Functions of the lymphatic system: l Transport lymph to the blood vessels l Protects the body ¢

Lymphatic vessels Lymphatic capillaries ¢ Lymphatic collecting vessels ¢ Lymphatic trunk ¢ Right lymphatic duct - drains lymph from: l Head right upper extremity l Right thorax l Drains into right subclavian vein ¢

Lymphatic vessels Thoracic duct – drains lymph from: l Rest of the body l Drains into left subclavian vein ¢ Cisterna chyli ¢ Characteristic of the lymphatic vessels l Walls with 3 tunics l Presence of valves l Presence of abundant anastomoses ¢

Lymphatic vessels

Primary lymphoid organs Bone marrow l Contain the stem cell that will give rise to all lymphocytes l Site of B cell differentiation or immunocompetency ¢ Thymus l Site of T cell differentiation or immunocompetency ¢

Thymus

Secondary lymphatic organs ¢ Lymph nodes l Bean-shaped l Numerous l Regional lymph nodes: • Cervical • Axillary • Inguinal, etc l Hilus l Afferent and efferent vessels

Secondary lymphatic organs ¢ Microscopy l Capsule and subcapsular sinus l Trabecula l Cortex • Outer cortex (follicles) • Germinal center containing dividing B cells • Deep cortex or paracortical area • Contain T cells

Secondary lymphatic organs l Medulla • Medullary cords • Medullary sinuses • Contain macrophages and plasma cells

Secondary lymphatic organs ¢ Spleen l Capsule l White pulp • Central artery • Lymphocytes l Red pulp • Venous sinuses • Reticular tissue • Macrophages arranged I splenic cords

Spleen

Lymphoid tissues ¢ Tonsils l One pharingeal l Two palatines l Two linguals l Presence of germinal center l Presence of crypts

Tonsils

The immune response It is a systemic response ¢ Destroys or neutralizes foreign substances ¢ Characteristics of immune responses l Memory • Immunocompetent lymphocytes are monospecific l Specificity l Ability to differentiate self from nonself ¢

The immune response Antigens l Foreign proteins l Polysaccharides l Haptens ¢ Lymphocytes l Responsible for the immune response ¢ Autoimmunity ¢

Organ, cells and cell interaction of the immune response Hemocytoblasts in the bone marrow give rise to lymphocytes ¢ Types of Lymphocytes: l B - will stay in the bone marrow for maturation (immunocompetence) l T - will migrate to thymus for maturation (immunocompetence) l Natural Killers ¢

Organ, cells and cell interaction of the immune response ¢ B and T cell will then leave bone marrow and thymus, enter the blood stream and travel to secondary lymphatic organs l Site for clonal selection

Organ, cells and cell interaction of the immune response B and T cell will bind to specific antigens and then undergo clonal multiplication ¢ B cell may become l Memory l Plasma cell l Humoral immunity ¢

Organ, cells and cell interaction of the immune response ¢ T cell may become l Memory l Cytotoxic l Helper l Suppressor l Cellular immunity

Antibodies and tests for their presence ¢ Characteristics of antibodies or Immunoglobulins (Igs) l Produced only by plasma cells l They are plasma proteins (gamaglobulins) l Found in all body secretions

Antibodies and tests for their presence Classes of antibodies l Ig. M, Ig. G, Ig. A, Ig. D, Ig. E ¢ Structure of the immunoglobulins l 2 heavy chains l 2 light chains ¢

Antibody