Organs of the immune system Primary and secondary

Organs of the immune system - Primary and secondary lymphoid organs. - Histological structure of lymphoid organs. - Function of lymphoid organs. Dr. Iman Thabet & Dr Sultan Alsharif

Dr. Iman Thabet & Dr Sultan Alsharif

Lymphatic System Network of vessels � � � Collects fluid from tissues Return fluid to blood Major cell is lymphocyte Dr. Iman Thabet & Dr Sultan Alsharif

lymphatic vessels Dr. Iman Thabet & Dr Sultan Alsharif

lymph üsimilar to blood plasma üwhite blood cells üdebris/pathogens Dr. Iman Thabet & Dr Sultan Alsharif

Thymus Gland � Lies above heart � Divides into 2 lobes � Development of regulatory T cells � Development Infant – obvious Puberty – maximum size Maturity – decreases in size Dr. Iman Thabet & Dr Sultan Alsharif

Thymus Dr. Iman Thabet & Dr Sultan Alsharif

Dr. Iman Thabet & Dr Sultan Alsharif

Bone marrow Structure Less well defined than thymus Role of stromal cells Function Hematopoiesis � B cell maturation � Dr. Iman Thabet & Dr Sultan Alsharif

Lymph Nodes � Oval structures located along lymphatics � Centers produce lymphocytes � Lymph flows through sinuses before exiting Dr. Iman Thabet & Dr Sultan Alsharif

Lymph Nodes Function 1 st line of response to antigens � Germinal center: is site of B cell proliferation & mutation � Specificity is high � Filter lymph � Help activate the immune system � Dr. Iman Thabet & Dr Sultan Alsharif

Spleen Located between the stomach & diaphragm Largest lymphatic organ Major cell types Lymphocytes Macrophages Dendritic cells RBCs Dr. Iman Thabet & Dr Sultan Alsharif

Spleen Function � Filters out older RBCs � Responds to antigens (Ags) in circulatory system � Produces activated B cells � Site of lymphocyte proliferation Dr. Iman Thabet & Dr Sultan Alsharif

Tonsils Contains lymphocytes & macrophages Germinal centers appear in response to Ags Protective role in the upper respiratory system Dr. Iman Thabet & Dr Sultan Alsharif