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Lymphatic System

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“The lymphatic system drains fluid from our tissue spaces”

Herlihy, B & Maebius, N, 2003, P.322

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The lymphatic system contains

lymph, the lymphatic vessels, the

lymphoid organs and lymphatic tissue that is widely distributed throughout the body

…

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How stuff works

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The Lymphatic System has three main functions …

The Lymphatic System returns tissue fluid to the blood

Specialised lymphatic vessels play an important role in the absorption of fats and fat soluble vitamins

The lymphoid tissue helps the body defend itself against disease

(Herlihy & Maebius 2003)

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Lymphatic System

A pathway for the drainage of tissue fluid.

Includes: • Lymph nodes• The Tonsils• The Thymus• The Spleen

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All About Lymph …

Lymph is a clear fluid that resembles plasma

Lymph is composed primarily of:

• Water• Electrolytes• Waste from metabolising cells• Protein that leaks out of systemic

circulation capillaries

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Where does lymph come from?

Lymph is formed from the plasma during capillary exchange …

Herlihy 2007 pg 265

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Where does it go to?

Lymph leaves the tissue space through the lymphatic vessels

The lymphatic vessels carry it to the heart and then empty it into the blood

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Fluid and dissolved substances are continuously filtered out of the blood capillaries into the interstitium to form tissue fluid.

About 90% of this tissue fluid moves back into the capillaries and is carried away as part of the venous blood

Herlihy, B & Maebius, N, 2003, P.323

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What about the other 10% of fluid?

The 10% of fluid that doesn’t re-enter the blood capillaries is drained by the lymphatic capillaries that surround the blood capillaries …

The tissue fluid that enters the lymphatic vessels is what we know as lymph

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Lymph Nodes

Small pea-shaped patches of lymphatic tissue that are strategically located so as to filter the lymph as it flows through the lymphatic vessels

Lymph nodes tend to appear in clusters

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Lymph Nodes

Made of specialized lymphoid tissue. Functions include:

• Removal of impurities• Processing of lymphocytes which aid in combating infection

Are usually massed together. Groups include:

• Cervical• Axillary• Tracheobronchial• Mesenteric• Inguinal

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Some of the larger clusters are:

• Cervical lymph nodes• Axillary lymph nodes• Inguinal lymph nodes

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How stuff works

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Lymph Node Structure

The walls of a lymph node are made from a single layer of epithelium and have large pores.

The pores allow the lymphatic capillaries to drain tissue fluid and protein and so form lymph

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Axillary nodes

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The Lymphatic Vessels

The lymphatic vessels include the lymphatic capillaries and several larger lymphatic vessels.

The lymphatic vessels, like blood vessels, form an extensive network throughout the body

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The distribution of lymphatic vessels is similar to that of the veins …

Every organ has a rich supply of lymphatic vessels that pick up the fluid and transport it to the heart

Herlihy, B & Maebius, N, 2003, P.323

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When the lymph is absorbed by the lymphatic capillaries it flows towards the heart in a series of larger and larger lymph vessels until it reaches the large lymphatic ducts …

Herlihy, B & Maebius, N, 2003, P.323

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The lymph from the right arm and right side of the head and thorax drains into the right lymphatic duct

The lymph from the rest of the body drains into the thoracic duct

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How stuff works

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Both ducts enter into the subclavian veins

The right lymphatic duct drains into the right subclavian vein

The thoracic duct drains into the left subclavian vein

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medicine.ucsd.ed/clinicalmed/head.html

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www.bt.cdc.gov/...trainingmodule/3/03.asp

Swollen axillary lymph node

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How lymph moves through the lymphatic vessels

Blood is pumped around the body by the heart

Lymph requires other mechanisms to move it through the lymphatic vessels

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Lymph moves in response to the following …

• The milking action of skeletal muscles

• The movement of the chest during respiration

• The rhythmic contraction and relaxation of smooth muscles in the lymph capillaries

Herlihy, B & Maebius, N, 2003, P.324

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Lymphoedma

• REF: thenakedscientists.com• “How the Lymphatic system works”• Stephanie Modi.

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The Lymphoid Organs

• Lymph Nodes

• The Tonsils• Thymus

Gland• The Spleen

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Lymphoid Tissue

Tonsils: Mass of lymphoid tissue that filters tissue fluid. Have a function in immunity during early childhood.

Thymus: key role in development of pre and post birth immunity.

Spleen: Lymphoid tissue that filters blood. Destroys worn out RBC . Cleans blood by phagocytosis. Dam for blood.

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The Tonsils …

The Tonsils are partially encapsulated lymph nodes in the throat area

They filter tissue fluid that is contaminated by pathogens that have entered the body through the nose or mouth or both

Herlihy, B & Maebius, N, 2003, P.326

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There are three sets of tonsils …

• The Palatine Tonsils

• The Pharyngeal Tonsils (The Adenoids)

• The Lingual Tonsils

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www.dentsl.mu.edu/...oraltonsil/oraltonsil.htm

Oral Tonsil

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The Thymus Gland

• Located in the upper thorax behind the sternum and below the thyroid gland

• It is most active in early life • Plays a crucial role in the development

of the immune system before birth and in the first months of life

• After puberty it shrinks and is replaced by connective tissue and fat

• It is concerned with the manufacture of T Cells

Herlihy, B & Maebius, N, 2003, P.327

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The Thymus Gland … cont.

The Thymus gland secretes hormones called Thymosins

Thymosins promote the maturation of lymphocytes within that gland

Thymosins also promote the growth and activity of lymphocytes in lymphoid tissue function throughout the body

Herlihy, B & Maebius, N, 2003, P.327

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www.dentsl.mu.edu/...oraltonsil/oraltonsil.htm

Thymus Gland

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The Spleen

• The Largest lymphoid organ in the body

• Located in the upper left quadrant of the abdominal cavity just beneath the diaphragm

• Normally protected by the rib cage• It shape and structure is similar to a

lymph node, only much larger!

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The Spleen … cont

• The Spleen filters blood rather than lymph

• The Spleen has two types of tissue:

- White Pulp- Red Pulp

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White Pulp

• Consists of lymphoid tissue• Lymphocytes that surround

arteries are found here

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Blood enters the spleen through the Splenic Artery

The blood flows through the spleen and is cleansed

Micro-organisms that are trapped in the spleen are destroyed by the Leukocytes

The cleansed blood leaves by the Splenic Vein

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The Spleen has other functions …

• The spleen acts as a storage area for blood

• The blood is released in an emergency

• The Spleen also destroys old worn out red blood cells

• The Spleen plays a role in erythropoiesisas a site of red blood cell production before birth

Herlihy, B & Maebius, N, 2003, P.327

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Red Pulp …

• Contains venous sinuses• The venous sinuses are filled

with blood, lymphocytes and macrophages

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www.ames.kiz.ia.us/...classrooms/21/Human.html

Spleen

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Disorders of the Lymphatic System

• Lymphangitis• Elephantiasis• Lymphadenitis• Lymphadenopathy• Splenomegaly• Hodgkin’s Disease• Lymphoscarcoma.

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References• Brown,D & Edwards,H. (2005) Lewis’s Medical

– Surgical Nursing. Assessment and Management of Clinical Problems. Elsevier , Sydney

• Memmler, R. L. & Wood, D. L. (1987) The Human Body in Health and Disease. (6th ed). J.B. Lippincott company, Philadelphia.

• Mosby’s (2002) Mosby’s Medical Nursing & Allied Health Dictionary. Elsevier, United States of America.

• Tortora, GJ & Grabowski, SR (1990) Principles of anatomy and physiology (6th ed).. HarperCollins Publishers Inc. New York.

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List of References

medicine.ucsd.ed/clinicalmed/head.htmlmedicine.ucsd.ed/clinicalmed/head.htmlwww.bt.cdc.gov/...trainingmodule/3/03.aspwww.cvm.tamu.edu/.../faq/question/cancer02.htmlwww.dentsl.mu.edu/...oraltonsil/oraltonsil.htmwww.dentsl.mu.edu/...oraltonsil/oraltonsil.htmwww.ames.kiz.ia.us/...classrooms/21/Human.html

Herlihy, B & Maebius, N, The Human Body in Health and Illness

2nd Edition,2003, Saunders, United States of America