Lymphatic system

KHAIRUL HADI ROZI TEE

(D20141066254)

TUAN HAZLAMI BIN RAJA ABU HASAN

(D20141066248)

IZUN BIN ITHNIN

(D20141066854)

DEFINITION

Introduction of Lymphatic System

Consists of organs, ducts, and nodes. It transports a watery clear fluid called lymph. This fluid distributes immune cells and other factors throughout the body.

It also interacts with the blood circulatory system to drain fluid from cells and tissues. The lymphatic system contains immune cells called lymphocytes, which protect the body against antigens (viruses, bacteria, etc.) that invade the body.

Structure of lymphatic

Main of Structure

MAIN FUNCTIONS

Maintain fluid balance

Defend the body against

disease by producing

Lymphocytes

Absord fats

What is Lymphocytes

A type of blood cell and important part of immune system

Defend the body against infection because they can distinguish the body’s own cell from foreign ones.

They recognize foreign material in the body, they produce chemical to destroy that material.

Type of lymphocyte before birth

Lymphocytes B Lymphocytes T

Stay within the bone marrow untill they are mature.

Once mature, they spread throught the body and concentrate in spleen and lymph nodes.

Leave the bone marrow and mature in the thymus

A gland found in the chest

Only mature Lymphatic can carry out immune responses.

Lymph Nodes

Lymph Nodes are small but very important structure in the lymphatic system, which is part of the larger immune system in the body.

These nodes act as filters, removing harmful particles and fighting off bacteria.

Lymph nodes found at neck, armpits, groin, and behind knees.

LYMPH NODES( ENCAPSULATED MASSES OF LYMPATIC TISSUE )

Lymph nodes are an important component of thebody's immune system and help in fighting infections.

Lymph nodes are located throughout the body, butvisible and palpable only when they are enlarged orswollen.

They are small, soft, round or oval structures that arefound throughout the body.

They are connected to each other in chain-like(lymphatic chains) fashion by channels similar to bloodvessels.

Each individual lymph node is covered by a capsulemade up of connective tissue.

Within the capsule, lymph nodes contain certain kindsof immune cells.

These cells are mainly lymphocytes, which produceproteins that capture and fight viruses and othermicrobes, and macrophages, which destroy and removethe captured material.

Lymph nodes often swell in one location when a problem such as an injury, infection, or tumor develops in or near the lymph node.

Which lymph nodes are swollen can help identify the problem ?

The glands on either side of the neck, under the jaw, or behind the ears commonly swell when you have a cold or sore throat.

Glands can also swell following an injury, such as a cut or bite, near the gland or when a tumor or infection occurs in the mouth, head, or neck.

Glands in the armpit (axillary lymph nodes) may swell from an injury or infection to the arm or hand. A rare cause of axillary swelling may be breast cancer or lymphoma.

The lymph nodes in the groin (femoral or inguinal lymph nodes) may swell from an injury or infection in the foot, leg, groin, or genitals. In rare cases, testicular cancer, lymphoma, or melanoma may cause a lump in this area.

Glands above the collarbone (supraclavicular lymph nodes) may swell from an infection or tumor in the areas of the lungs, breasts, neck, or abdomen.

Lymph nodules( Small unencapsulated masses of lymphatic tissue )

Found beneath the epithelium of all mucous membranes, that is, the tracts that have natural openings to the environment.

Destroy pathogens that penetrate the epithelium of the respiratory, digestive, urinary, or reproductive tracts.

Tonsils are the lymph nodules of the pharynx ; peyer’s patches are those of the small intestine.

Example of lymph nodes

Tonsils The tonsils (palatine tonsils) are a pair of soft tissue

masses located at the rear of the throat (pharynx)

Each tonsil is composed of tissue similar to lymph nodes, covered by pink mucosa (like on the adjacent mouth lining)

Running through the mucosa of each tonsil are pits, called crypts

The tonsils are part of the lymphatic system, which helps to fight infections.

removal of the tonsils does not seem to increase susceptibility to infection.

Tonsils vary widely in size and swell in response to infection.

Example of tonsils

SPLEEN

The spleen is a brown, flat, oval-shaped lymphatic organ that filters and stores blood to protect the body from infections and blood loss.

Protected by our ribs, the spleen is located between the stomach and the diaphragm in the left hypochondriac region of the abdominal body cavity. The splenic artery branches off from the aorta and the celiac trunk to deliver oxygenated blood to the spleen, while the splenic vein carries deoxygenated blood away from the spleen to the hepatic portal vein. A tough connective tissue capsule surrounds the soft inner tissue of the spleen

SPLEEN

Spongy inner tissue within the spleen contains many tiny blood vessels and hollow sinuses that store blood. The spleen can release its stored blood into circulation to replace blood lost during a traumatic injury. Many platelets are also stored with the blood in the spleen to help form blood clots to prevent further blood loss.

Around the vessels and sinuses of the spleen are regions of red pulp and white pulp with a marginal zone in between.

The red pulp regions contain many net-like reticular fibers that filter worn-out red blood cells from the blood flowing through the spleen. Captured red blood cells are digested to recycle the iron and protein components of hemoglobin.

The marginal zone between the red and white pulp acts as a filter to capture pathogens in the blood and pass these pathogens on to the white pulp.

White pulp regions of the spleen are made of lymphatic tissue containing macrophages, T lymphocytes, and B lymphocytes that destroy pathogens in the blood and produce antibodies. The spleen may enlarge during certain infections due to an increase in the number of white blood cells, captured pathogens and antibodies inside the spleen.

Inside the spleen

The spleen is not a vital organ – its functions are useful but not essential for life.

Red bone marrow, the liver, and lymph nodes can complete the filtration and blood recycling functions of the spleen in its absence.

Because it is not a vital organ and is so soft, spongy, and vascular, damage to the spleen is almost always treated by its complete removal.

Untreated damage to the spleen can quickly lead to massive internal hemorrhaging and eventual death.

Thymus gland The thymus gland, despite containing glandular tissue

and producing several hormones, is much more closely associated with the immune system than with the endocrine system. The thymus serves a vital role in the training and development of T-lymphocytes or T cells, an extremely important type of white blood cell. T cells defend the body from potentially deadly pathogens such as bacteria, viruses, and fungi.

The thymus is a soft, roughly triangular organ located in the mediastinum of the thoracic cavity anterior and superior to the heart and posterior to the sternum It has two distinct but identical lobes that are each surrounded by a tough, fibrous capsule. Within each lobe is a superficial region of tissue called the cortex and a histologically distinct deep region called the medulla. Epithelial tissues and lymphatic tissues containing dendritic cells and macrophages make up the majority of both regions of the thymus.

Image of Thymus

The function of the thymus is to receive immature T cells that are produced in the red bone marrow and train them into functional, mature T cells that attack only foreign cells. T cells first reside within the cortex of the thymus where they come in contact with epithelial cells presenting various antigens. The immature T cells that respond to the antigens corresponding to foreign cells are selected to survive, mature, and migrate to the medulla while the rest die via apoptosis and are cleaned up by macrophages. This process is known as positive selection.

Upon reaching the medulla, the surviving T cells continue to mature and are presented with the body’s own antigens. T cells that bind to the body’s own antigens test positively for autoimmunity, whereby they attack the body’s own cells instead of only foreign cells. Autoimmune T cells are eliminated by apoptosis in a process known as negative selection, resulting in only around 2% of the immature T cells reaching maturity.

Several hormones produced by the thymus promote the maturation of the T cells prior to their release into the bloodstream. The now mature T cells circulate through the body where they recognize and kill pathogens, activate B cells to produce antibodies, and store the memory of past infections.

Unlike most organs that grow until the age of maturity, the thymus enlarges throughout childhood but slowly shrinks from the onset of puberty and throughout adulthood.

As the thymus shrinks, its tissues are replaced by adipose tissue.

The shrinking is due to the reduced role of the thyroid in adulthood – the immune system produces most of its T cells during childhood and requires very few new T cells after puberty.

Unlike most organs that grow until the age of maturity, the thymus enlarges throughout childhood but slowly shrinks from the onset of puberty and throughout adulthood.

As the thymus shrinks, its tissues are replaced by adipose tissue. The shrinking is due to the reduced role of the thyroid in adulthood – the immune system produces most of its T cells during childhood and requires very few new T cells after puberty.

Thanks for your attention