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Cards In This Set
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Understand the general functions and characteristics of the lymphatic system.
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Consists of 2 semi-independent parts: a meandering network of lymphatic vessels & lymphoid tissues & organs scattered throughout the body. Function: Returns interstitial fluid & plasma proteins that have escaped the circulatory system back to the blood (3 L every 24 hours)
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Be able to compare the anatomical structure of veins with that of lymphatic vessels.
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Lymphatic vessels have the same 3 tunics as veins. They have thinner walls, with more internal valves. They anastomose (reconnect) more frequently.
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Understand how lymphatic vessels are able to obtain oxygen and nutrients from the vascular system.
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Collecting vessels in the skin travel with superficial veins. Deep vessels travel with arteries. Nurtients are supplied from branching vasa vasorum.
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Be able to identify the major lymphatic trunks of the body
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Paired lumbar, bronchomediastinal, subclavian, and jugular trunks.
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Understand the mechanisms for moving lymph through lymphatic vessels.
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The lymphatic system lacks an organ that acts as a pump. Vessels are low-pressure conduits. It uses the same methods as beins to propel lymph: skeletal muscle movements, pulsations of nearby arteries, and contractions of smooth muscle in the walls of the lymphatics.
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Which cells, as discussed in lecture, are considered "professional antigen presenting cells," and what do they do?
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T cell lymphocytes: manage the immune response including the detecting and presentation of foreign antigens. They attack and destroy foreign cells.
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Where in the body do we find the major regions of "clusters" of lymph nodes?
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Clustered along lymphatic vessels. Cervical, inguinal, and axillary (armpit).
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Spleen Characteristics
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Largest lymphoid organ, located on left side of ab. cavity beneath the diaphragm. Extends to curl slightly around the anterior aspect of the stomach. Served by splenic artery and vein which enter and exit at the hilus.
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How lymph follicles and nodes are able to function based on their cellular and structural characteristics.
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Nodes- bean shaped and surrounded by a fibrous capsule. Trabeculae- extended inward from the capsule and divide the node into compartments. nodes have 2 histologically distinct regions: cortex & medulla. The cortex contains follicles with germinal centers, heavy with dividing B cells. Dendritic cells nearly encapsulate the follicles. The deep portion of the cortices house T cells in transit. T cells circulate continuously among blood, lymph nodes, and lymphatic sytream. Medullary cords extend from cort. and contain B cells, T cells, and plasma cells. Throughout the node are lymph sinuses crisscrossed by reticular fibers that have macrophages on the fibers.
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Spleen Functions
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Site of lymphocyte proliferation, immune surveillance and response, cleanses the blood, stores RBCs and breakdown products of RBCs for later reuse, site of fetal erythrocyte production, stores blood platelets.
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Thymus Characteristics
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Bilobed organ that secretes hormones (thymosin and thmopoietin) that cause T lymphocytes to become immunocompetent. Size varies with age. Has outer cortex (densely packed lymphocytes and scattered macrophages) and inner medulla (contains fewer lymphocytes and thymic (Hassall's) corpuscles.
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Thymus Functions
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Strictly in T lymphocyte maturation. Does NOT directly fight antigens. Stroma of thymus is star shaped epithelial cells. Thymocytes are released when they become immunocompetent.
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Tonsils Characteristics
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Simplest lymphoid organ; form a ring of lymphatic tissue around the pharynx
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Palatine tonsils
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Either side of the posterior end of the oral cavity
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Lingual tonsils
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Lie at the base of the tongue
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