The Lymphatic Syste m

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The Lymphatic System

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The Lymphatic Syste m. What is the lymphatic system?. A n extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections . Together with lymphoid organs and tissues, provide the structural basis of the immune system. Lymphatic characteristics. - PowerPoint PPT Presentation

Transcript of The Lymphatic Syste m

Page 2: The Lymphatic Syste m

What is the lymphatic system?

An extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections.

Together with lymphoid organs and tissues, provide the structural basis of the immune system

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Lymphatic characteristics One way system to the heart

Carries clean fluids back to the blood

Drains excess fluid from tissues Lymph is a clear, watery fluid that

contains protein molecules, salts, glucose, urea, and other substances — throughout the body.

Removes antigens from the body and exposes antigens to the immune system Lymph may contain macrophages,

viruses, bacteria, cellular debris and even traveling cancer cells.

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What type of vessels make up the lymphatic system?

Vessels are called lymphatics Thin walled and analogous to

veins

2 large ducts Right lymphatic duct Thoracic duct Both empty into the right and

left subclavian veins

Drained by the right lymphatic duct

Drained by thoracic duct

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Lymphatic Organs Lymph nodes Spleen Thymus Tonsils Peyer’s patches

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Lymph nodes Principal lymphoid organs of the body

Most are bean shaped organs along lymphatic collecting vessels Up to 1 inch in size

Grouped together at various parts of the body Clusters of both superficial LNs deep

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Lymph nodes Superficial

Cervical Axillary Inguinal

Deep Tracheobronchial Aortic Iliac

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Circulation in the lymph nodes Lymph

Enters via afferent lymphatic vessels

Travels through large subcapsular sinus and smaller sinuses

Exits the node at the hilus via efferent vessels

Afferent vessels

Efferent vessels

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Critical Thinking Question Why are there more afferent lymphatic vessels carrying

lymph to the lymph nodes than there are efferent lymphatic vessels?

Answer: Fewer efferent vessels, causing flow of lymph to stagnate,

allowing lymphocytes and macrophages time to carry out functions

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What function do lymph nodes have? Filter lymph

macrophages destroy microorganisms and debris

Immune system—lymphocytes are activated and mount an attack against antigens

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Lymphangiogram

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Spleen Largest lymphoid organ

Filters blood (lymph nodes filter lymph) Filters blood of bacteria, viruses, and other debris (blood-borne

antigens “white pulp” Removes and destroys worn out red blood cells (RBCs)

Stores platelets

Site of lymphocyte production and immune surveillance and response

In fetus only: RBC are made in the spleen

Susceptible to injury; splenectomy increases risk of bacterial infection

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Spleen

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Thymus Differs from other lymphoid organs in important

ways It functions strictly in T lymphocyte maturation

T cells become Immunocompetent It does not directly fight antigens

Size with age In infants, it is found in the inferior neck and extends

into the mediastinum, where it partially overlies the heart

Increases in size and is most active during childhood

Stops growing during adolescence and then gradually atrophies

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Critical Thinking Question Why does the thymus increases in size and is MOST active during

childhood, stops growing during adolescence and then starts getting smaller?

Answer: The thymus produces a large amount of T cells so by the time a person

reaches puberty, the body has a lot of lymphocytes. The thymus also produces a variety of hormones and plays an important role in the development of immunologic competence in fetus and child.

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Tonsils Simplest lymphoid organs

Form a ring of lymphatic tissue around the pharynx

Crypts trap and destroy bacteria and particulate matter

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Mucosa-associated lymphoid tissue (MALT)

Mucosal surfaces within the body are protected by the mucosal immune system consisting of the mucosa-associated lymphoid tissue or MALT

An extensive diffuse system of small concentrations of lymphoid tissue found in various sites of the body such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin to protect from foreign matter.