The Structure and Functions of the Lymphatic System

The above video details an overview of the Lymphatic System. It covers the following information.

The main functions of the lymphatic system are:

1. Removal of bacteria and any abnormal material
2. Helps prevent infection
3. Drains away excess fluids which are then eliminated from the body

Lymph is colourless, clear, and similar to a watery fluid resembling blood plasma which it supplies to tissues for their metabolism. It is filtered through the walls of the capillaries. In the spaces between the cells where there are no blood capillaries lymph provides nourishment.

It also carries lymphocytes; these are a type of white blood cell. There is also another type of white blood cell present which lines the inside walls of the lymph nodes. Macrophages destroy and engulf any debris, bacteria or foreign bodies carried in the lymph. They also manufacture antibodies to fight bacteria, which pass into the blood stream along with the circulating lymph. When we suffer from an infection, the lymph nodes that are nearest to the infectious site will swell (oedema) and as the white cells fight the bacteria the area tends to become tender.

The lymphatic system has no muscular pump (heart) as does the blood circulation. The lymph moves through the vessels and gets around the body through the movements of the large muscles contracting. Lymph travels in one direction, from body tissue back towards the heart.

Through massaging the body, the lymph flow is stimulated, the flow is assisted and the removal of waste products increased.

Lymph vessels and Nodes

Lymph vessels contain valves along their vessels to prevent lymph flowing backwards. The vessels run very close to the veins around the body, and are very similar in structure to veins.

The vessels join to form larger lymph vessels, until they eventually flow into one or two large lymphatic vessels; these are the thoracic duct (or left lymphatic duct) and the right lymphatic duct. The thoracic duct receives lymph from the left side of the head, neck, chest, abdomen and lower body. The right lymphatic duct receives lymph from the right side of the head and upper body.

These large lymph vessels then empty their contents into a vein at the base of the neck, which then empties into the vena cava. The lymph is then mixed into the venous blood as it returns to the heart. It is extremely important when massaging to ensure the movements are directing the blood and lymph flow back towards the heart.

Oedema is the swelling of the tissues. This can occur when fluids accumulate instead of returning to the blood stream.

Lymph nodes are usually called glands. They are tiny oval structures usually between 1mm and 25mm in length, which filter the lymph, extracting the bacteria, and defending the body by fighting against infection, destroying any harmful bacteria. Lymphocytes are found in the lymph glands, and produce the antibodies which fight against the invasion of any micro-organisms.

Lymph nodes of the head

• Buccal group: these drain the eyelids and the nose, skin and face.
• Mandibular group: drains the lips, chin, nose and cheeks.
• Mastoid group: drains the temple area and skin of the ears.
• Occipital group: drains the back of the scalp and upper neck area.
• Sub-mental group: drains the lower lip and chin.
• Parotid group: drains the ears, eyelids and nose.

Lymph nodes of the neck

• Superficial cervical group: drains the back of head and neck.
• Lower deep cervical group: drains the back area of neck and scalp.

Lymph nodes of the neck and chest

These nodes are in the armpit: Axilla glands drain the various areas of the chest and arms.

When massaging, the direction applied is to move the lymph towards the nearest lymph nodes, this then encourages the fast removal of waste products.