Lymphatic System Study Guide PDF

DR. Amany Abdelfattah Lymphatic system 1ry lymphatic organs 2ry Lymphatic organs * Bone Marrow * Lymph node * Thymus * Spleen...

DR. Amany Abdelfattah Lymphatic system 1ry lymphatic organs 2ry Lymphatic organs * Bone Marrow * Lymph node * Thymus * Spleen * Tonsils Thymus A flattened bilobed organ lying behind the sternum. ❑ Structure: I. Stroma: capsule & trabeculae. II. Parenchyma: formed of thymic lobules. ❑ Each lobule is formed of: 1) Cortex: outer dark part (high content of lymphocytes). 2) Medulla: central pale part of the thymus lobule (due to low content of lymphocytes). ❑ Function: Production of T- lymphocytes → Cell-mediated immunity. Lymph follicle The structural and functional unit of most lymphoid organs Rounded basophilic mass formed of small lymphocytes (mainly B lymphocytes & few T lymphocytes).  DR. Amany Abdelfattah Lymph Node ❑ Lymphatic organ that is widely distributed all over the body. ❑ Structure: I. Stroma: capsule & trabeculae II. Parenchyma: cortex & medulla. 1. The cortex: formed of lymphatic follicles 2. The medulla: formed of irregular medullary cords (as follicles but arranged in the form of cords). ❑ Function: filtration of lymph Spleen ❑ Structure: Stroma: capsule & trabeculae Parenchyma: white bulb & red bulb. 1) White pulp: lymphatic follicles containing follicular artery. 2) Red pulp: formed of blood sinusoids & splenic cords (lymphatic tissue mixed with blood). Tonsil ❖ Masses of lymphatic tissue present in the lamina propria of a mucous membrane. ❖ Types: 1. Palatine tonsil 2. Pharyngeal tonsil 3. Lingual tonsil  DR. Amany Abdelfattah Palatine tonsil ❑ Two masses of lymphatic tissue embedded in the C.T. under the mucous membrane of oro-pharynx. ❑ Structure: Non-keratinized stratified squamous epithelium. Lymphatic tissue: lymph follicles & diffuse lymphocytes Capsule. ❑ Function: Quick defense against infective agents taken with food through formation of antibodies