Structure and Functions of the Lymphatic System

Functions of the Lymphatic System Fluid balance When blood moves through the capillaries fluid from the blood plasma leaks into the interstitial spaces Lymphatic capillaries around the blood capillaries absorb this excess fluid and bring it back to the blood Fat absorption Lymphatic capillaries line the small intestine and absorb fat which is then transferred to the blood Defense Pathogens are filtered from lymph nodes and the spleen

Types of Lymphatic Tissue Diffuse Lymphatic Tissue: Dispersed tissue that contains immune cells Found around the lymphatic nodules Lymphatic Nodules: Dense tissue arranged into a compact, spherical structure Found within the lymph nodes and the spleen

Lymphatic Vessels Carry lymph from the tissues to the bloodstream Contain one way valves that push the lymph within them to the bloodstream with the help of surrounding muscles

Lymph Nodes Small, round disks throughout the lymphatic vessels Filter lymph and remove pathogens Contain Germinal Centers which are site of lymphocyte production

External Lymph Node Structure Capsule: Protective covering on the outside with extensions called trabecula that divide the lymph node into sections Afferent Lymphatic Vessels: Carry lymph to the node Efferent Lymphatic Vessels: Carry lymph away from the node

Inner Lymph Node Structure Cortex: outer sections made up of lymphatic nodules, germinal centers, diffuse lymphatic tissue, and lymphatic sinuses Sinus = space between tissues Medulla: inner section made up of diffuse lymphatic tissue and lymphatic sinuses

Lymph Nodes Location Lymph nodes are found all around your body, but they are concentrated in areas where pathogens are most likely to enter the body Ex: Digestive System, Lungs, Reproductive System

Lymph Movement Lymph is moved through the lymph vessels towards the thoracic duct and right lymphatic duct which dump the lymph into the subclavian veins https://www.ck12.org/biology/lymphatic- system/lecture/Lymphatic-System- Animation/?referrer=concept_details

Tonsils Groups of lymph nodes and lymph tissue that protects the pharynx against harmful substances and bacteria

Spleen Has a capsule and trabeculae on the outside with white pulp and red pulp inside White Pulp: produces white blood cells and makes antibodies Red Pulp: filters antigens, microorganisms, and defective/old red blood cells out of the blood Blood moves through the Splenic Artery → White Pulp → Red Pulp → Splenic Veins

Thymus Where T Cells that are made from stem cells in the red bone marrow come to mature