25.7
Estructura y funciones detalladas de los ganglios linfáticos
Los ganglios linfáticos son estructuras con forma de frijol que se agrupan a lo largo de los vasos linfáticos en las regiones inguinal, axilar y cervi…
Los ganglios linfáticos son pequeñas estructuras en forma de frijol que se agrupan a lo largo de los vasos linfáticos. Se localizan principalmente en las regiones inguinal, axilar y cervical.
Estos ganglios tienen una cubierta externa llamada cápsula, que extiende las trabéculas hacia adentro, dividiendo el ganglio en compartimentos.
Desde el punto de vista histológico, cada ganglio linfático se puede dividir en corteza superficial y médula profunda.
La corteza está formada por células dendríticas, macrófagos y folículos densamente empaquetados de linfocitos B. Tras la presentación del antígeno por parte de las células dendríticas, los linfocitos B maduran y se convierten en células plasmáticas productoras de anticuerpos y células B de memoria.
La corteza interna está formada principalmente por linfocitos T migrados desde la corteza. También contiene células dendríticas, que pueden activar los linfocitos T.
La linfa ingresa a los ganglios linfáticos a través de los vasos linfáticos aferentes y fluye a través de los senos paranasales llenos de fibras reticulares, linfocitos y macrófagos.
La linfa se filtra dentro de estos senos paranasales. Los macrófagos eliminan las sustancias extrañas a través de la fagocitosis, mientras que los linfocitos destruyen los patógenos mediante respuestas inmunitarias.
La linfa filtrada sale del ganglio linfático a través de los linfáticos eferentes y emerge del otro extremo del ganglio en el hilio.
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Q1: What are the main structural regions within a lymph node?
Lymph nodes contain two primary histological regions: the superficial cortex and the deep medulla. The cortex houses dendritic cells, macrophages, and densely packed B lymphocyte follicles. The inner cortex consists mainly of T lymphocytes and dendritic cells. The medulla contains activated B and T lymphocytes that distribute throughout the body after immune activation.
Q2: How do B lymphocytes mature within lymph nodes?
When dendritic cells present antigens to B lymphocytes in the cortex, the B cells mature into antibody-producing plasma cells and memory B cells. These activated cells then enter the medulla, where they are distributed throughout the body. This process enables the adaptive immune response to foreign substances.
Q3: What is the path lymph takes through a lymph node?
Lymph enters via multiple afferent lymphatic vessels at the node's convex surface and flows into the subcapsular sinus beneath the capsule. It then travels through trabecular sinuses parallel to the trabeculae and into medullary sinuses. Finally, lymph exits through one or two broader efferent lymphatic vessels at the hilum.
Q4: How do lymph nodes filter pathogens and foreign substances?
Sinuses within lymph nodes contain reticular fibers, lymphocytes, and macrophages that trap foreign substances. Macrophages eliminate pathogens through phagocytosis, while lymphocytes destroy them using immune responses. The slow lymph flow through multiple sinuses allows extended filtration time before lymph returns to the blood.
Q5: Why does lymph flow slowly through lymph nodes?
Multiple afferent vessels bring lymph into each node, but only one or two efferent vessels carry it out. This structural arrangement creates a bottleneck that slows lymph transit through the node. The reduced flow rate allows more time for immune cells and macrophages to filter and eliminate pathogens before lymph returns to circulation.
Q6: Where are lymph nodes located in the body?
Lymph nodes are small, bean-shaped structures that cluster along lymphatic vessels in three major regions: the inguinal nodes in the groin, axillary nodes in the armpits, and cervical nodes in the neck. These strategic locations allow lymph nodes to monitor and filter lymph from different body areas.
Q7: What role do dendritic cells play in lymph node function?
Dendritic cells in the cortex present antigens to B lymphocytes, triggering their maturation into plasma cells and memory B cells. In the inner cortex, dendritic cells activate T lymphocytes. These antigen-presenting functions enable lymph nodes to coordinate adaptive immune responses against pathogens.