Masters of Health Magazine September 2022 | Page 80

Fluid Balance

While supplying oxygen and nutrients to the body, the blood plasma leaks fluid outward at the capillary level into tiny interstitial spaces surrounding the cells.  Lymph capillaries connect these spaces to the lymphatic system.  Since this interstitiel or

extracellular fluid cannot reenter the blood vessels, the lymphatic system provides an accessory return route to the blood to maintain a dynamic equilibrium.

Fluid overload in the interstitial spaces creates hydrostatic pressure, which then drives the fluid into the lymphatic capillaries.  Hydrostatic pressure forces the fluid overload in the interstitial spaces into the lymphatic capillaries.  While in the lymphatic capillaries and collecting vessels, interstitial and lymph fluids are similar at first. 

However, the lymph changes composition along its course as it passes through lymph vessels and mixes with other substances.  Once in the lymphatic system, this extracellular, clear, colorless fluid, now called lymph, drains into lymphatics, which are larger vessels.  This whole process prevents the accumulation of excess tissue fluid or edema.

Lymph contains oxygen, glucose, amino acids, sodium, potassium, chloride, bicarbonate, magnesium, calcium, small amounts of amino acids, vitamins, enzymes, and other nutrients needed by tissue cells.  It also helps regulate hormones.

While on its way back to the bloodstream, lymph fluid passes through tiny lymphatic capillaries that infuse almost every tissue in the body.   A dense amount of these minute vessels enrich the lungs, gut, genitourinary system, and skin dermis.  However, the skin epidermis, mucus membranes, bone marrow, and central nervous system do not contain any lymphatic capillaries.  

Before emptying into the bloodstream, lymph fluid also makes its way through the spleen and thymus to the lymph nodes.  When bacteria enter the lymph channels, it is transported to lymph nodes to be isolated.  Lymph can also transport Metastatic cancer cells.

Lymph nodes, located at intervals, filter the lymph to remove foreign materials such as infectious microorganisms.  Valves prevent lymph from flowing backward.  There are primary valves at the lowest level of the lymphatics vessels and bi-leaflet secondary valves in larger collecting vessels that actively pump the lymph.  Pumping occurs through movement or intrinsic contractility of specialized muscle cells in lymphatic vessel walls.  Circular exercises and muscle contractions pressing on the lymph nodes help transport lymph through the vessels. 

These vessels converge to form larger vessels called lymphatic trunks, connected to veins at the base of the neck.  One trunk connects to the right lymphatic duct to drain the upper right portion of the body and return the lymph to the bloodstream via the right subclavian vein.  The other connects to the thoracic duct, which drains the rest of the body into the left subclavian vein. 

By way of the lymphatic vessels, the lymphatic system removes this remaining fluid and particulate matter (collected from all bodily tissues) via the veins into the bloodstream.  A disruption of fluid processing can result in lymphedema or edema.

The primary lymphoid organs are the thymus which generates lymphocytes from immature progenitor cells, and bone marrow, which manufactures white blood cells (leukocytes).  The different types of white blood cells are granulocytes (neutrophils, eosinophils, basophils, and mast cells), monocytes, and lymphocytes (T cells and B cells).