The Lymphatic Syste m What is the lymphatic system? - PowerPoint Presentation

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The Lymphatic System

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

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.

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

Lymphatic Organs

Lymph nodes

Spleen

Thymus

Tonsils Peyer’s patches

Lymph nodes

Principal lymphoid organs of the body

Most are bean

shaped organs along lymphatic collecting vessels

Up to 1 inch in sizeGrouped together at various parts of the bodyClusters of both

superficial

LNs deep

Lymph nodes

Superficial

Cervical

Axillary

Inguinal Deep Tracheobronchial

Aortic

Iliac

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

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

What function do lymph nodes have?

Filter lymph

macrophages destroy microorganisms and

debris

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

Lymphangiogram

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 responseIn fetus only: RBC are made in the spleen

Susceptible to injury;

splenectomy

increases risk of bacterial infection

Spleen

Thymus

Differs from other lymphoid organs in important

ways

It functions strictly in T lymphocyte

maturationT cells become

Immunocompetent

It does not directly fight

antigensSize with ageIn 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

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.

Tonsils

Simplest lymphoid organs

Form a ring of lymphatic tissue around the

pharynx

Crypts trap and destroy bacteria and particulate matter

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.

MALT

Examples:

GALT (gut-associated lymphoid tissue, such as the

Peyer's

patches in the lining of the small intestines, as well as the adenoids, tonsils, and appendix)

BALT (bronchial-associated lymphoid tissue in the bronchi)