Introduces the lymphatic system as vessels and organs that return lymph to the bloodstream, regulate fluid balance and filter pathogens, then covers its definition, structure, functions and a clinical link to cancer spread. Goes on to describe how lymph forms from plasma and interstitial fluid, the superficial and deep vessel groups, lymph nodes, and organs such as the tonsils, thymus and spleen, and the main cellular and fluid components of lymph.
Topic 20 of 104 in the MU Sofia syllabus for Physiology (Dental Medicine, Year 2). The free AceMed note covers it in 2 sections, about 604 words (4 min of reading), with 21 flashcards.
In this note
Introduction
Lymphatic System: Formation and Composition
Introduction
The lymphatic system is a system of specialized vessels and organs whose main function is to return the lymph from the tissues back into the bloodstream.
Lymphatic system is considered as a part of both the circulatory and immune systems. The functions of the lymphatic system complement the bloodstream functions, as it regulates the balance of fluids in the body and filters the pathogens from the blood.
Definition
The lymphatic system is a network of vessels and organs that regulates the amount of fluid in the human body and defends it against infections.
Structure
Lymphatic capillaries; lymphatic vessels, ducts and tracts; primary and secondary lymphoid organs,
Function
Fluid regulation; immune surveillance; transport of large molecules
Clinical relations
Cancer spreading
Anatomy
The lymphatic system begins with the lymphatic capillary meshwork that collects the excessive fluid from the tissues.
The lymph travels from the tissues through larger lymph vessels until it reaches its destination point; the bloodstream. On the way, it traverses lymphoid organs filled with immune cells that monitor if there are any pathogens in the incoming lymph.
Lymph is a clear, yellowish fluid present in most tissues of the body. It is created as a result of the filtration of the plasma. The plasma from the blood diffuses through the porous capillary wall into the tissues to deliver nutrients. After feeding the hungry cells on the periphery, the majority of fluid gets reabsorbed back into the blood vessels, while around 10% of the fluid stays in the tissue.
Lymphatic capillaries are the smallest lymphatic vessels that collect the interstitial fluid from the tissues. They are organized in networks called lymphatic plexuses. Plexuses converge to make larger lymphatic vessels that carry the lymph away from the tissues and into the bloodstream.
The lymphatic vessels are divided into two large groups; superficial(skin) and deep lymphatic vessels (organs).
The lymph nodes are secondary lymphoid organs distributed throughout the whole body, grouped according to the body regions they are in (e.g. axillary, pelvic, mediastinal lymph nodes).
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