University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2022
Views:

326

Pages:

45
Author:

Campbell Wagner

LYMPHOID TISSUE PART 2 SPLEEN AND THYMUS Objectives Lymph node Describe the structural organization of lymphoid tissue in general and of the thymus, lymph nodes, lymph nodules (follicles) and spleen. Detail how antigens are removed from the lymph and the blood via the sinuses and reticular cells of the lymph nodes and the spleen. Trace the movements of cells and fluid through the lymph node and the spleen. Part 1 Lymph nodes and gut-associated lymphoid tissue Part 2 Spleen and thymus Spleen Functions of the spleen are the filtration of blood; destruction of aged erythrocyte; pitting of reticulocytes, production site of lymphocytes and antibodies from differentiated plasma cells, and activated lymphocytes. Open circulation involves the dumping of blood into splenic cords from penicillar arterioles. From here the formed elements of blood must reenter circulation by passing through narrow slits through endothelial stave cells. This steps filters the blood. The filtered blood passes into the venous sinusoids and returns to circulation, but macrophages destroy the old and dead cells. Function of the thymus is to produce T lymphocytes in an antigen free environment blood thymus barrier in cortex of thymus. SPLEEN OVERALL STRUCTURE VASCULAR ARRANGEMENT WHITE PULP • CENTRAL ARTERY • PERIARTERIOLAR LYMPHATIC SHEATH • FOLLICLES - B LYMPHOCYTES RED PULP • VENOUS SINUSES • PULP CORDS (BILLROTH’S STRANDS) • MARGINAL ZONE SPLEEN OVERALL STRUCTURE VASCULAR ARRANGEMENT Spleen Spleen (reticulum stain)- capsule and reticulum fibers Spleen 122 WHITE PULP SPLEEN • CENTRAL ARTERY • PERIARTERIOLAR LYMPHATIC SHEATH • FOLLICLES - B LYMPHOCYTES RED PULP • VENOUS SINUSES • PULP CORDS (BILLROTH’S STRANDS) • MARGINAL ZONE Spleen: 1. Central artery 2. Periarteriolar lymphatic sheath 3. Red pulp Spleen 122 Marginal zone Spleen central artery 122 Spleen central artery PENICILLARY ARTERIES Marginal zone 122 Splenic red pulp: 1. Venous sinus 2. Littoral cell 3. Billroth’s strand 218 Spleen reticulum: 1. Reticulum fiber 2. Billroth’s strand 3. Sinuses SPLEEN RETICULAR FIBER FRAMEWORK • RETICULUM CELL - MESODERM BLOOD FLOW SPLEEN • PENICILLARY ARTERIES macrophages BLOOD FLOW cells = picketSPLEENLittoral fence type endothelial • PENICILLARY ARTERIES BILLROT (splenic)’S STRANDS cells of vascular sinus Litteral cells of spleenic venial Spleen #19752 (UT117?) 117 Litteral cells of spleenic venial Spleen # 19752 (UT117?) 117 SPLEEN BLOOD FLOW • FILTRATION • REMOVAL OF OLD RED BLOOD CELLS Littoral cells = picketfence type endothelial cells of vascular sinus SPLEEN BLOOD FLOW • FILTRATION • REMOVAL OF OLD RED BLOOD CELLS Blood flow in spleen Slide 47: Spleen Capsule Trabeculae Red pulp White pulp Slide 47: Spleen White pulp Central artery surrounded by peri-arterial lymphatic sheath Red pulp Splenic cords (Billroth’s strands) Venous sinuses Blood flow in spleen SPLEEN BLOOD FLOW • FILTRATION • REMOVAL OF OLD RED BLOOD CELLS SPLEEN BLOOD FLOW • FILTRATION • REMOVAL OF OLD RED BLOOD CELLS THYMUS GROWTH PATTERN - REGRESS AFTER CHILDHOOD RETICULUM FRAMEWORK – EPITHELIUM (from endoderm) CORTEX - ABSENCE OF EXOGENOUS ANTIGENS • EPITHELIAL MICROENVIRONMENT • LYMPHOPOIESIS • BLOOD-THYMUS BARRIER MEDULLA Thymus maturation THYMUS GROWTH PATTERN - REGRESS AFTER CHILDHOOD THYMUS RETICULUM FRAMEWORK - EPITHELIUM EPITHELIUM THYMUS CORTEX - ABSENCE OF EXOGENOUS ANTIGENS • EPITHELIAL MICROENVIRONMENT • LYMPHOPOIESIS • BLOOD-THYMUS BARRIER (cortical barrier only) MEDULLA THYMUS CORTEX AND MEDULLA Slide 48: Thymus (1 yr old child) Medulla Cortex Capsule Septae Medulla with lymphocytes and reticular cells Cortex with tightly packed lymphocytes Hassall’s corpuscle THYMUS CORTEX EPITHELIUM THYMUS CORTEX Mitosis Mitosis THYMUS CORTEX T cell death THYMUS CORTEX AND MEDULLA CORTEX MEDULLA THYMUS MEDULLA Hassall’s corpuscles Clinical Correlation Infections often cause enlargement of lymph nodes that receive lymph from the infected area. Malignant tumor cells can also "metastasize" via the lymph vessels as well. http://swollenlymphglands.wordpress.com/ Copyright McGraw-Hill Companies Copyright McGraw-Hill Companies thymus Bone marrow STRUCTURE OF LYMPHOID SYSTEM COMPONENTS