Lymphatic system and its diseases

Structure, Functions and Common Disorders of Lymphatic System

By the end of this session students are expected to be able to:

Define Lymphatic System

• Explain the Organization of Lymphatic System
• the Structures Lymphatic System
• Describe Functions of Lymph System

List the Common Disorders of the Lymphatic System

What is lymphatic system?

Definition and Organization of Lymphatic System

Lymphatic system: A network of tissue, organs, and vessels that help to maintain the body‘s fluid balance, cleanse the body fluid of foreign matter and provide immune cells (lymphocytes) for defence

Composition of Lymphatic System

Lymph, the fluid corrected by the system from the interstitial spaces of the tissue and returns to the bloodstream.

Lymphatic plexuses, networks of small lymphatic vessels, lymphatic capillaries, that originate in the extracellular spaces of most tissues.

Lymphatic system and its diseases

Lymphatic vessels (lymphatics), a nearly body wide network of thin-walled vessels with valves, originating from lymphatic plexuses along which lymph nodes are located.

Lymph nodes, small masses of lymphatic tissue through which lymph is filtered on its way to the venous system.

Lymphocytes, circulating cells of the immune system that react against foreign materials/microbes.

Lymphatic system and its diseases

Lymphoid tissue, sites that produce lymphocytes, such as that found in the walls of the digestive tract; in the spleen, thymus, and lymph nodes; and in myeloid tissue in red bone marrow.

Lymphatic system and its diseases

The lymphoid tissue is primarily involved in immune responses, and consists of lymphocytes and other white blood cells enmeshed in connective tissue through which the lymph passes.

Lymphatic system and its diseases

The lymphatic system differs from the circulatory system in the way that, the lymphatic do not form a closed ring or circuit.

Instead, it begins blindly in the intercellular spaces of the soft tissues of the body.

The Specialized organs of the lymphatic system are tonsils, thymus, bone marrow and spleen.

Tonsils

Masses of lymphoid tissue located in a protective ring under mucous membranes in the mouth and back of the throat.

Help protect against bacteria that may invade tissues in the area around the openings between the oral and nasal cavities.

They are:

• Palatine tonsils; located on each side of the throat.
• Pharyngeal tonsils; are near the posterior openings of the nasal cavity.

Lingual tonsils; located near the base of the tongue

Lymphatic system and its diseases

The tonsils serve as the first line of defence from the exterior and as such are subject to chronic infection (tonsillitis).

Thymus

• The thymus is located inferior to the thyroid gland.

In the foetus and infant, the thymus is large and extends under the sternum

Lymphatic system and its diseases

The thymus hormones are necessary for immunological competence by enabling the T-cells to participate in the recognition of foreign antigens and provide immunity.

This capability of T cells is established early in life and then is perpetuated by the lymphocytes themselves.

Lymphatic system and its diseases

The new-born‘s immune system is not yet fully mature, and infants are more susceptible to certain infections than are older children and adults.

Usually by the age of 2 years, the immune system matures and becomes fully functional

Spleen

A soft, elongated wedge shaped purple organ Spleen is located in the left hypochondrium directly below the diaphragm, above the left kidney and descending colon, and behind the fundus of the stomach

…

The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries.

The red pulp consists of venous sinuses filled with blood and cords of lymphatic cells, such as lymphocytes and macrophages.

Arteries leading into each compartment are surrounded by dense masses (nodules) of developing lymphocytes

Lymphatic system and its diseases

Near the outer regions of each compartment is tissue called red pulp made up of fine reticular fibres submerged in blood that comes from nearby arteries.

Lymphatic system and its diseases

After passing through the reticular meshwork, blood collects in venous sinuses and then returns to the heart through Subclavian veins.

Bone marrow

Bone marrow is responsible for the production of blood cells: red blood cells, white blood cells, and platelets. Bone marrow stem cells play an important role in immunity as they generate lymphocytes

Functions of Lymph System

Maintenance of fluid balance in the body It returns excess fluid and proteins from the tissues that cannot be returned through the blood vessels.

Lymphatic system and its diseases

The fluid is found in tissue spaces and cavities, in the tiny spaces surrounding cells, known as the interstitial spaces. These are reached by the smallest blood and lymph capillaries

Proteins that accumulate in the interstitial spaces can return to the blood only via lymphatic vessels.

Plasma filters into the interstitial spaces from blood flowing through the capillaries.

Much of this interstitial fluid is absorbed by tissue cells or reabsorbed by the blood before it flows out of the tissue.

A small amount of interstitial fluid is left behind.

Lymphatic system and its diseases

Loss of the lymphatic system would be fatal within a day. Without the lymphatic system draining excess fluid, our tissues would swell, blood volume would be lost and pressure would increase

If this would continue over even a brief period of time, the increased interstitial fluid would cause massive oedema.

This oedema would causes tissue destruction or death.

Lymphatic system and its diseases

This problem is avoided by the presence of lymphatic vessels that act as “drain’’ to collect the excess fluid and return it to the venous blood just before it reaches the heart.

Absorption and transport of dietary fat,

In which special lymphatic capillaries (lacteals) receive all absorbed fat (chyle) from the intestine and convey it through the thoracic duct to the venous system(left subclavian vein).

Lymphatic system and its diseases

Lacteals (lymphatics in the villi of the small intestine) serve an important function in the absorption of fats and other nutrients(salts,proteins,water, glucose)

Immunity

Production of lymphocytes which are necessary for fighting against pathogens When foreign protein drains from an infected area, antibodies specific to the protein are produced by immunologically competent cells and/or lymphocytes and dispatched to the infected area.

Common Disorder of the Lymphatic System

• Includes;
• 1.enlargement of the lymph nodes (lymphadenopathy)

2.swelling due to lymph node blockage (also known as lymphedema)

3.cancers involving the lymphatic system,

Lymphadenopathy

• An enlargement of the lymph nodes

Usually caused by infection, inflammation, or cancer.

Lymphatic system and its diseases

Infections that cause lymphadenopathy include; bacterial infections such as streptococcal throat infection, locally infected skin wounds, or viral infections such as mononucleosis or HIV infection.

Lymphatic system and its diseases

Inflammatory or autoimmune conditions occur when a person's immune system is active, and can result in enlargement of lymph nodes. This can happen in lupus.

Lymphedema

swelling due to lymph node blockage

It occurs when a person has had surgery and/or radiation to remove a cancer, the lymphatic flow back to the heart.

• Lymphangitis

-Inflammation of lyphatic vessels

This most commonly occurs in women who have had surgery to remove a breast cancer.

Part of the operation to remove the breast cancer involves removing lymph nodes in the armpit

Infectious causes of lymphangitis

Elephantiasis/ filariasis

Lymphoma

• cancer of the lymph nodes.
• It occurs when lymphocytes grow and multiply uncontrollably.

Eg Hodgkins lymphoma

Lymphatic system and its diseases

https://www.livescience.com/26983-lymphatic-system.html#:~:text=The%20most%20common%20diseases%20of%20the%20lymphatic%20system,oncology%20and%20hematology%20at%20Kaiser%20Permanente%20in%20Atlanta.

Key Points

Lymphatic system is a network of tissue, organs, and vessels that help to maintain the body‘s fluid balance, cleanse the body fluid of foreign matter and provide immune cells for defence.

Lymphatic system is composed of lymph, lymphatic plexus, lymphatic vessels, lymph nodes, lymphocytes and lymphoid tissue.

The main structures of lymphatic system are tonsils, thymus and spleen Functions of the lymphatic system are maintenance of fluid balance in the internal environment and immunity Common disorders of the lymphatic system are: lymphadenopathy, lymphedema and lymphoma

Evaluation

• What is lymphatic system?
• What are the components of the lymphatic system?
• What are the functions of lymph system?

What are the common disorders of the lymphatic system?

Assignment

Explain structure and functions of lymphatic system

Common Disorder of the Lymphatic System

• Includes;
• 1.enlargement of the lymph nodes (also known as lymphadenopathy)

2.swelling due to lymph node blockage (also known as lymphedema)

cancers involving the lymphatic system,

Lymphatic system and its diseases

Infections that cause lymphadenopathy include; bacterial infections such as strep throat, locally infected skin wounds, or viral infections such as mononucleosis or HIV infection.

Eg elephantiasis, filariasis