Lymph Definition
This system is present in the body of vertebrates. Vessels, tissues, and organs are responsible for the composition of lymph. The lymph tissue fluid helps in maintaining fluid balance. It does so by collecting the excess fluid from tissues and then deposits it into the bloodstream. The lymph circulatory system also generates lymphocytes that help in fighting against the diseases. The fluid that runs through the lymphatic system is known as lymph tissue fluid. Further, we will understand more about the composition and function of lymph.
Lymph Structure
The lymphatic system in the human body is made up of lymph, lymphatic vessels, lymphatic nodes, and lymphoid tissue. Lymph fluid is a colourless, watery fluid that mainly consists of white blood cells and is carried by the lymphatic system. The lymph vessels are the site of fluid drainage. They pump the lymph fluid with the help of skeletal and smooth muscles. To prevent the backflow the larger lymph vessels are present with valves. A lymph node is nothing but a mere collection of lymphoid tissue. They are located at regular intervals in the lymphatic system. Lymphoid tissue is composed of lymphocytes along with other specialized cells and tissues. The chief function of the lymph nodes is that it helps in maintaining the immune system functions. The lymphatic system diagram is shown below.
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Lymph Circulation
After reading about the chief function of lymph nodes you must be thinking about that where does lymph drain? Well, the answer to this question will be covered under this topic. The lymphatic system can be thought of as a drainage system that is needed by the body because blood circulates and its plasma is leaked into the thin walls of the capillaries. Extracellular fluid is the portion of the blood plasma that escapes and it contains oxygen, amino acid, and other useful nutrients that are needed by the body and tissue cells. Almost all of the fluid gets back into the bloodstream but a small percentage of it along with the particulate matter is left behind. Here then comes the role of the lymphatic system which helps in removing these fluids and materials from tissues which thus prevents the fluid imbalance in the body. This imbalance can lead to the death of the organism. This lymph gets drained into larger vessels that are known as lymphatic vessels and these vessels converge to form the lymphatic trunk. These lymphatic trunks are connected to the veins and thus the excess materials or the infectious microorganisms are removed via this pathway. These lymphatic vessels are punctuated at intervals by small masses of lymph tissue which are known as lymph nodes.
Lymphoid Organs
The body lymph system is divided into primary lymphoid organs and secondary lymphoid organs. The primary lymphoid organs are the sites of B and T cells maturation sites and the secondary lymphoid organs are where these cells are further differentiated and perform their functions. The thymus, bone marrow, fetal liver are the primary lymphoid organs. Thymus and bone marrow are the major key players in immune function. The cells that mature in the bone marrow are termed B cells and the cells that migrate from bone marrow to thymus are called T cells. When these B and T cells mature they are migrated to the secondary lymphoid organs via the bloodstream where they are activated by coming in contact with the foreign materials which are termed as antigen. Lymph nodes, spleen, tonsils are termed secondary lymphoid organs. This is where these matured cells perform their function.
Composition and Function of Lymph
We will learn about the composition and function of lymph in these two paragraphs. The lymph plasma is almost similar to the blood plasma. Globulin proteins along with antibodies are present in lymph. Floating amoeboid cells are known as lymph corpuscles and the white corpuscles are known as lymphocytes.
Chief Functions of Lymph Nodes
Here we will understand the function of lymph in our body. The functions are:
It helps to transport oxygen, nutrients, hormones, etc.
The lymph nodes are responsible for producing lymphocytes. It transports these lymphocytes from the lymph nodes to the blood.
They help in destroying the foreign particles that invade the human body.
They help in absorbing the fat from the intestines.
FAQs on Lymph Tissue Fluid
1. What exactly is lymph, and what is it made of?
Lymph is a clear to pale-yellow fluid that circulates throughout the lymphatic system. It is essentially blood plasma that has leaked out of blood capillaries to surround body cells. Once this fluid, known as interstitial fluid, enters the lymphatic vessels, it is called lymph. Its composition is similar to blood plasma but with far fewer proteins and no red blood cells. It primarily contains water, salts, and a high concentration of white blood cells, especially lymphocytes.
2. How is lymph formed in our body?
Lymph formation is a continuous process. As blood flows through tiny capillaries, high pressure forces some of the watery plasma out into the spaces between body cells. This fluid is called interstitial fluid. While most of this fluid seeps back into the blood capillaries, a portion of it is collected by a network of even tinier vessels called lymphatic capillaries. The moment this interstitial fluid enters the lymphatic capillaries, it is officially known as lymph.
3. What are the main functions of the lymphatic system?
The lymphatic system has three primary functions that are vital for the body:
- Fluid Balance: It drains excess fluid from body tissues and returns it to the bloodstream, which prevents swelling (edema).
- Immune Defence: It is a major part of the immune system. Lymph nodes filter the lymph, trapping and destroying pathogens like bacteria and viruses using specialised white blood cells.
- Fat Absorption: It absorbs digested fats and fat-soluble vitamins from the small intestine and transports them into the bloodstream.
4. How is lymph different from blood?
While both are circulatory fluids, lymph and blood have key differences. Blood is red because it contains red blood cells, whereas lymph is clear or yellowish as it lacks them. Blood contains platelets and a high concentration of proteins, which are mostly absent in lymph. Furthermore, blood circulates in a closed loop pumped by the heart, while lymph flows slowly in one direction in an open system, eventually draining into the bloodstream.
5. What happens if lymph does not drain properly from the tissues?
If the lymphatic system fails to drain excess fluid from the tissues, the fluid accumulates in the spaces between cells. This condition is called edema, which leads to swelling in the affected body part. Edema can occur due to blockages in lymphatic vessels or damage to lymph nodes and is a sign that the fluid balance in the body has been disrupted.
6. Why is it so important that lymph gets filtered through lymph nodes?
Filtering lymph through lymph nodes is a critical step in the body's immune defence. As lymph travels from the tissues, it can pick up debris, cancer cells, and pathogens like bacteria and viruses. The lymph nodes act as biological filters, packed with immune cells (like lymphocytes and macrophages) that trap and destroy these harmful substances before the cleaned fluid is returned to the bloodstream. This process helps prevent infections from spreading throughout the body.
7. Is interstitial fluid the same thing as lymph?
They are almost identical in composition, but their name changes based on their location. When fluid seeps out of blood capillaries and bathes the body's cells, it's called interstitial fluid. As soon as this same fluid enters a lymphatic vessel, its name changes to lymph. So, the main difference is not what they are, but where they are.
