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Spleen, thymus Organs of the Lymphatic System

The lymphatic system has both primary and secondary organs. The primary organs, where lymphocytes are generated, include the bone marrow and thymus gland. The bone marrow produces B lymphocytes and plasma cells, while the thymus gland helps mature T lymphocytes. The secondary organs, where adaptive immune responses are initiated, include the lymph nodes, spleen, and other mucosa-associated lymphatic tissues like Peyer's patches and tonsils. The spleen filters the blood and removes old red blood cells, bacteria, and foreign matter. The thymus gland plays a key role in developing T lymphocytes from childhood through adolescence.

Health & Medicine◦
Lymphatic System part. II BY: Amen Ullah Lecturer: Surgical 12/25/2018 studyforum911@hotmail.com 1
Organs of the Lymphatic System Primary organs Red bone marrow Thymus gland Secondary organs Lymph nodes Lymph nodules Spleen 12/25/2018 studyforum911@hotmail.com 2
1. Primary lymphoid organs: Where lymphocytes are generated a. Bone marrow B lymphocytes are mature in bone marrow. Produce plasma cells, which secrete antibodies. Antibodies immobilize antigens and “tag” them for destruction by leukocytes (WBCs) b. Thymus gland T lymphocytes are mature in thymus. Manage the immune response. Attack and destroy foreign cells. 12/25/2018 studyforum911@hotmail.com 3
2. Secondary lymphoid organs : Initiate adaptive immune responses Lymph node Spleen Appendix Peyer’s patches Tonsils 12/25/2018 studyforum911@hotmail.com 4
Spleen  Location  Left epigastric region  between 9th-11th rib  in line of 10th rib • Largest lymphatic organ in the body. Function  The spleen helps body fight infection  Contains lymphocytes and macrophages Macrophages engulf and destroy bacteria, dead tissue, and foreign matter  The spleen removes these elements from the Bloodstream 12/25/2018 studyforum911@hotmail.com 5
THYMUS THYMUS ANATOMY o The thymus is a two-lobed structure that is positioned in the upper chest cavity. o The thymus is situated above the pericardium of the heart, in front of the aorta, between the lungs, below the thyroid, and behind the breastbone. o The thymus has a thin outer covering called a capsule. Features o Consists of two elongated lobes o Is a large organ in the fetus o Occupies the thoracic cavity behind the sternum o Secrete lymphopoietin 12/25/2018 studyforum911@hotmail.com 6
THYMUS 12/25/2018 studyforum911@hotmail.com 7
THYMUS  Functions at peak levels only during childhood  Produces hormones (like thymosin) to program lymphocytes  The thymus gland is the main organ of the lymphatic system. Located in the upper chest region.  The primary function of this gland is to promote the development of specific cells of the immune system called T lymphocytes.  T lymphocytes (T-cells) are white blood cells that protect against foreign organisms (bacteria and viruses) that have managed to infect body cells. They also protect the body from itself by controlling cancerous cells.  From infancy to adolescence, the thymus is relatively large in size.  After puberty, the thymus begins to decrease in size and continues to shrink with age 12/25/2018 studyforum911@hotmail.com 8
THYMUS HISTOLOGY  Thymus consist of three cells: Epithelial cells - tightly packed cells that give shape and structure to the thymus. Lymphocytes - immune cells that protect against infection and stimulate an immune response. Kulchitsky cells { neuroendocrine }- hormone- releasing cells. 12/25/2018 studyforum911@hotmail.com 9
Conti…  Each lobe of the thymus contains many smaller divisions called lobules.  A lobule consists of an inner area called the medulla and an outer region called the cortex.  The cortex region contains immature T lymphocytes. The medulla region contains the larger, mature T- lymphocytes.  While T lymphocytes mature in the thymus, they originate from bone marrow stem cells.  Immature T-cells migrate from the bone marrow to the thymus via the blood.  The "T " in T lymphocyte stands for thymusderived. 12/25/2018 studyforum911@hotmail.com 10
Mucosa-Associated Lymphatic Tissue (MALT) Includes: • Peyer’s patches • Tonsils • Other small accumulations of lymphoid tissue 12/25/2018 studyforum911@hotmail.com 11
Tonsils • Definition : The tonsils are small masses of lymphoid tissue that ring the pharynx (the throat) • The function: Their job is to trap and remove any bacteria or other foreign pathogens entering the throat. • Disorder : sometimes they become congested with bacteria and become red, swollen, and sore,a condition called tonsillitis 12/25/2018 studyforum911@hotmail.com 12
Tonsils 12/25/2018 studyforum911@hotmail.com 13
Lymphadenitis (adenitis) • Swelling (enlargement) of lymph glands • Occurs when infection present and body making WBCs to fight infection 12/25/2018 studyforum911@hotmail.com 14
Peyer’s Patches “Tonsils of the intestine” • Found in the wall of the small intestine • Capture and destroy bacteria in the intestine 12/25/2018 studyforum911@hotmail.com 15
THANK YOU 12/25/2018 studyforum911@hotmail.com 16