Immunology Lecture 2 LO PDF

**Primary Lymphoid Organs** Sites where lymphocytes mature and develop, including the bone marrow (where B cells mature) and thymus (where T cells mature). **Secondary Lymphoid Organs** Organs where immune responses are initiated, including lymph nodes, spleen, and mucosa-as...

**Primary Lymphoid Organs** Sites where lymphocytes mature and develop, including the bone marrow (where B cells mature) and thymus (where T cells mature). **Secondary Lymphoid Organs** Organs where immune responses are initiated, including lymph nodes, spleen, and mucosa-associated lymphoid tissues (MALT). **Tertiary Lymphoid Organs** Ectopic lymphoid structures that form in sites of chronic inflammation or infection, supporting local immune responses. --- **Yellow Bone Marrow** Fatty tissue in the medullary cavities of long bones, involved in fat storage and can convert to red marrow under increased blood cell production needs. --- **Red Bone Marrow** Active hematopoietic tissue in flat bones and the ends of long bones where blood cell production occurs. --- **Medullary Cavity** Central cavity within long bones containing bone marrow responsible for blood cell production. --- **Reticular Cell** Cells in lymphoid tissues providing structural support through a network of reticular fibers. --- **Endosteal Niche** Specialized microenvironment in the bone marrow adjacent to the bone surface, supporting hematopoietic stem cells. --- **Bone Marrow Vascular Niche** Microenvironment in the bone marrow where blood vessels and stromal cells interact with hematopoietic cells, regulating hematopoiesis. --- **Capsule (Thymus)** Outer connective tissue layer encasing the thymus, providing structural support and protection. --- **Subcapsular Space (Thymus)** Area immediately beneath the thymic capsule containing developing thymocytes. --- **Cortex (Thymus)** Outer region of the thymus where thymocytes undergo positive selection and maturation. --- **Medulla (Thymus)** Inner region of the thymus where thymocytes undergo negative selection and mature T cells are released into the bloodstream. --- **Thymic Involution** Gradual decrease in the size and function of the thymus with age, impacting the production of new T cells. --- **MALT (Mucosa-Associated Lymphoid Tissue)** Lymphoid tissues located at mucosal surfaces, including GALT, BALT, and NALT, protecting mucosal surfaces by initiating immune responses. --- **Follicles** Clusters of B cells in secondary lymphoid organs where B cell activation and proliferation occur. --- **Afferent Blood Vessels** Vessels bringing blood to a lymphoid organ, supplying oxygen and nutrients and allowing immune cells to enter. --- **Efferent Blood Vessels** Vessels carrying blood away from a lymphoid organ, allowing the exit of immune cells and waste products. --- **Red Pulp (Spleen)** Tissue in the spleen responsible for filtering blood, removing old or damaged red blood cells and pathogens. --- **White Pulp (Spleen)** Tissue in the spleen containing lymphocytes, involved in immune responses and antibody production. --- **Periarteriolar Lymphoid Sheath (PALS)** Region of white pulp in the spleen surrounding central arterioles, containing T lymphocytes and involved in initiating immune responses. --- **Germinal Center** Specialized microenvironment within lymphoid follicles where B cells proliferate and differentiate. --- **B Cell Corona** Outer layer of a germinal center consisting mainly of B cells, supporting the germinal center. --- **Marginal Zone** Region at the boundary between red and white pulp in the spleen, containing specialized macrophages and B cells. --- **Perifollicular Zone** Area surrounding lymphoid follicles in secondary lymphoid organs, containing T cells and involved in coordinating immune responses. --- **Peyer’s Patches** Aggregations of lymphoid tissue in the ileum of the small intestine, playing a key role in monitoring intestinal bacteria and initiating immune responses. --- Feel free to use these for your study or review sessions! ¡Define & describe the flow of lymph through lymph nodes & how blood enters spleen (DITKI) 1.Lymph fluid passes through the Afferent lymphatic vessel into the sub-capsular space (aka marginal sinus) 2.Travels through the cortical (aka trabecular sinus) to the medullary sinus 3.Exits medullary sinus through Efferent lymphatic vessel 4.Transported in lymphatic vessels to other lymph nodes & eventually returned to the blood