Lymphatic System and Immunity

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Lymphatic System

=Lymph =Lymphatic vessels =Lymphatic tissue =Lymphatic nodules =Lymph nodes =Tonsils =Spleen =Thymus

Lymphatic Vessels

--Carry lymph away from tissues -Lymphatic capillaries *More permeable than blood capillaries *Epithelium functions as series of one-way valves

Functions of the Lymphatic System

Fluid balance Excess interstitial fluid enters lymphatic capillaries + becomes lymph Fat abs. Abs, of fat + other substances frm digestive tract Defense Microorganisms + other foreign substances are filtered from lymph by lymph nod + frm blood by spl

Lymphatic Vessels

Carry lymph away from tissues -Lymphatic capillaries= *More permeable than blood capillaries *Epithelium functions as series of one-way valves Lymphatic capillaries join to form Lymphatic vessels *Have valves that ensure one-way flow

Lymphatic Vessels II

Lymph nodes: Distributed along vessels and filter lymph Lymphatic trunks: Jugular, subclavian, bronchomediastinal, intestinal, lumbar Lymphatic ducts: Right and thoracic which connect to large veins

Lymphatic Tissue and Nodules

-Lymphatic tissue *Consists mainly of lymphocytes *Encapsulated or not -Lymphatic nodules *Numerous in loose connective tissue of digestive (Peyer’s patches), respiratory, urinary, reproductive systems

Tonsils

-Large groups of lymphatic nodules in nasopharynx and oral cavity -Provide protection against bacteria and other harmful material Groups *Palatine *Pharyngeal *Lingual

Lymph Nodes

Organized in cortex and medulla Substances removed by phagocytosis or stimulate lymphocytes or both Only structures to filter lymph **Afferent and efferent vessels

Spleen

-Can be ruptured in traumatic abdominal injuries resulting in bleeding, shock, death -Blood flows through at 3 different rates Fast (most), slow, intermediate -Functions: Destroys defective RBCs Detects + responds 2 foreign subst -reservoir for bld

Thymus

-Located in superior mediastinum -Divisions: Cortex and medulla -Site of maturation of T cells