Question

Describe the general flew of lymph from lymphatic capillaries through return to three circulatory system. Include relevant structures and functional aspects of this journey.

Answer 1

The circulatory and lymphatic systems interact with each other. When the blood flows through the capollaries, due to the high pressure, some plasma and white blood cells ooze out through the thin walls of the capillaries. This fluid which is the lymph, moves into the interstitial space , taking nutrients and other essential materials to each and every cell. They also collect the waste from these cells. Now, this fluid needs to be returned back to the blood so that the cardiovascular system continues to function normally, and this is what the lymph vessels do.

The lymphatic system contains three parts-- * lymphatic vessels

* lymph fluid and

* and lymph nodes which cleanse the lymph as it passes through it.

Lymphatic vessels are one way vessels i.e. through it, the flow of fluid [lymph] is only towards the heart.

They are like drainage vessels which are extremely important because otherwise the fluid might have collected in the interstitial space causing different types of problems.

Lymph transport begins at the very tip of microscopic lymphatic capillaries which are present in almost all the tissues except in the bones, teeth and the central nervous system where excess tissue fluid is drained into the cerebrospinal fluid.

The high interstitial fluid pressure makes the fluid enter the lymph capillaries. Now this fluid is known as lymph. As the lymph passes through the lymph nodes , any pathogen that might have entered our body is dealt with. A special set of lymphatic capillaries called lacteals transports absorbed fats from the small intestine to the blood stream.

From lymphatic capillaries the lymph flows through larger and thicker walled channels into the collecting vessels , then the trunks , and finally into the largest vessels called 'ducts'.

The larger collecting vessels unite to form lymphatic trunks, which drain fairly large areas of the body. The major trunks , which are named after the area of the body they drain lymph from are paired. They are :

* Lumbar

* Bronchomediastinal

* Subclavian ,and

* Jugular

Only the Intestinal trunk is single.

The lymph is eventually delivered to one of the two large ducts in the thoracic region.

The right lymphatic duct drains lymph from the right upper limb and the right side of the head and thorax.

The thoracic duct ,which is much larger receives lymph from the rest of the body. It arises as a large sac called called the cisterna chyli, that collects lymph from the two large lumbar trunks that drain the lower limb and from the intestinal trunk that drains the digestive organs.

The thoracic duct receives lymphatic drainagr froom the left side of the thorax, left upper limb and the left side of the head.

Each terminal duct empties its lymph into the veinous circulation at the junction of the internal jugular vein and sub clavian vein in its own side of the body.

The lymphatic system lacks a pump and the same mechanism which works for the veins as they bring back blood to the heart , works for the lymph also. Besides this , the pulsations in nearby arteries help in lymph flow. Added to thi the walls of the lymphatic walls, which are made of smooth muscles, throb rhythmically to pump the lymph inside them.