Exam 3: Lymphatic Tissue Flashcards
lymphatic system
consists of cells, tissues, and organs that form part of the body’s immune system - protects body from harmful substances
Classified as primary or secondary
Primary lymphatic tissue
Bone Marrow, Thymus
Sites of development and maturation of lymphocytes into immunocompetent cells
Donor of lymphatics
Secondary lymphatic tissues
lymph nodes
MALT (mucosa-associated lymphatic tissue) - GALT (gut), BALT (bronchus), GU tract, tonsils
Spleen
Sites of formation of immunological defense against antigens or pathogens. Confrontation with antigens or pathogens occur here
Receiver of lymphatics
Diffuse Lymphatic tissue (MALT)
loose lymphatic tissue, simplest organization (may be loosely arranged or have more prominent basophilic structure), not sharply delineated
mostly lymphocytes, but also monocytes, acidic macrophages, and plasma cells
Reticular fibers support suspended cells
Diffuse lymphatic tissue is located in
lamina propria of some other organ - wall of GI tract (GALT), respiratory tract (BALT), or GU tract - places infection may be
Lymphatic Nodules (follicles)
Non-encapsulated, spherical, dense aggregations of lymphocytes with some organization
May be primary or secondary
May be solitary or aggregate
Primary lymphatic nodules
appears homogenous throughout, has mostly small lymphocytes
Spherical structure, no capsule
Suspended with reticular fibers
Secondary lymphatic nodules
Has 2 distinct zones
Corona (mantle) zone - outer, dark staining zone containing mature (small) lymphocytes
Germinal center - inner, light staining zone containing immature (medium or large) lymphocytes
Antigens cause germinal center to swell
Solitary lymphatic nodules
temporary structures
May appear, disappear, and reappear at a particular site
Lymphatic aggregates
permanent nodules
Peyer’s patches (B & T lymphocytes) - permanent aggregations in ileum
Lymphatic tissue in appendix - permanent aggregations in lamina prpria and submucosa of appendix
BALT in respiratory tract
Lymphatic nodules in tonsils, lymph nodes, and spleen
Tonsils
Aggregates of lymphatic nodules with B-lymphocytes (escape into lumen of pharynx and oral cavity)
Form a ring surrounding entrance to oropharynx
Have partial CT capsule - sends septa into interior of tonsil for protection from spread of tonsilar infections
Pharyngeal, Palatine, and lingual tonsils
Pharyngeal Tonsil (Adenoid)
Located in nasopharynx
Covered by pseudostratified columnar epithelium with cilia
No crypts, has pleats instead
Palatine Tonsils
Pair, each tonsil located in lateral wall of oropharynx between palatoglossal and palatopharyngeal arches
Covered by stratified squamous nonkeratinized epithelium with B-lymphocytes
Has many epithelial-lined pits - crypts that divide tonsil
Contain many lymphatic nodules with germinal centers (where B lymphocytes are produced)
Lingual Tonsils
Small bumps on dorsal surface of posterior 1/3 of tongue
Covered by stratified squamous nonkeratinized epithelium
Has crypts
Lymph Nodes
lymphatic organs located along path of lymphatic vessels to filter lymph before it passes into blood vascular system
