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Lymphatic System
© Roger Jahnke O.M.D.
The lymphatic system has been much neglected in most Western scientific traditions. Contrasted with the heart, for example, the lymph is relatively unexplored. Perhaps, because lymph and lymph vessels are generally translucent they drew little attention in early anatomical study compared to organs, blood vessels, muscles and bones.
Hippocrates and Aristotle referred to "white blood" and "colorless fluid" but in the Middle Ages medical knowledge declined and the lymph was temporarily forgotten. In 1627 Asellius, in Milan, recovered the knowledge of the lymph.(38) The structure and action of the lymph system was still undefined by 1900(39) and the both the immunological function of the lymph and the actual lymphogenic process are not clearly understood even today.
In general, the lymphatic system is a network of organs, tissues,vessels, nodes and flow potentials. It collects interstitial fluid, infused with the by products of cellular activity, and transports it centrally where it rejoins the blood system. In this role it regulates endogenous metabolites and waste products.(40)
In addition, the lymphatic system is a primary component of the immune system helping to protect the body from a broad range of pathogenic factors.(40) It carries fluids infused with bacteria, virus, fungus into immuno-active lymph nodes where lymphocytes, reticular cells and macrophages kill or neutralize toxic or enemy cells, substances and organisms. In this role it regulates exogenous disease inducing agents.(40)
The lymphatic system also has a nutritional function wherein it assists in bringing nutritional factors into proximity with the tissues. This was noted by Asselius in his original discovery of the chyle filled vessels of a recently fed dog.(38) In the 1970's the broad based nutritional (or trophic) function of the lymph system began to get deeper exploration.(41)
Like the early medical explorers in Europe, the founders of Oriental medicine also did not specifically note the lymph, except non-specifically as a component of the body fluids.(28,29) However, there is an important difference between the empirical science of Asia which did not clearly delineate the lymph and the deductive science of the West that gave the lymph little note.
In Western science, until recently the nearly invisible lymph, received little of the focus it deserves and few if any health generating strategies or modalities were based on its function. In the orient, where science is based on trial and error and the invisible "Qi" is honored, the results of healthy and unhealthy lymphatic function were noted in healthy individuals and contrasted in unhealthy individuals. Even though the lymphatic function itself was unknown and unnamed, its effects were generally ascribed to the proper action of Qi or Prana (energy) and fluids. In Asia an elaborate system for generating and circulating lymph was developed through the self care practices of Qigong and Yoga/Pranayama.
When we look carefully at these practices in relation to what we now know about lymphatic function and its healing role it appears as if much of Qigong and Yoga/Pranayama practice were developed specifically with the enhancement of lymphatic function in mind. Breath, movement and posture all have specific effects on the production and circulation of the lymph.
In the West we have divided the body fluids (blood, lymph, cerebrospinal fluid, synovial fluid, extracellular fluid, intracellular fluid) into specific categories. From the paradigm of the west it seems the Chinese may have overlooked important information with their broad, non specific view of "Qi, blood and fluids". However, the lymph fluid is actually part cellular water and part blood plasma. The blood plasma is actually comprised, in part, from lymph fluid.(38) Some of the cerebrospinal fluid finds its way into the lymphatic system.(42) In this way each of the individual fluids really make up one fluid. Do we miss something by the reduction of integrated systems into a multitude of separate categories and parts? May we learn something by simultaneously embracing or, at least exploring, the more simplified view of the Asian traditions?
Qigong and Yoga/Pranayama practice appear to activate a number of mechanisms associated with the lymphatic system:
- Lymph generation
- Lymph propulsion
- Immune function
- Cerebrospinal fluid circulation
- Nutritive function
The actual generation of the lymph has long been attributed to the filtration
of blood plasma from the capillaries (40). As recently as 1985 this was
recognized as the primary source of the lymph. This idea overlooks a significant
detail that is at the essence of the tremendous health benefits of Qi
Gong. A major portion of the body's lymph is produced by the identical
physiological process that generates the body's chemical energy.(68)
To recapitulate oxidative phosphorylation:
6O2 + C6H12O6 + (BMR) = Ergs + 6CO2 + 6H2
Six molecules of water are generated for each six molecules of oxygen that are metabolized in energy production.
In a moderately active 70 Kg human between 2100 and 2800cc of lymph enters the blood stream daily at the sub-clavian vein through the thoracic duct. Through the calculations of the Krebs cycle the cells are producing approximately 950cc (30) of pure interstitial water daily. In a vigorously active person or one engaging in minimally strenuous exercise, such as walking, Qigong or Pranayama up to1400cc of aerobically generated interstitial water can be produced, circulated and eventually passed into the subclavian vein daily.
Not only is the formula for oxidative phosphoylation the basis of chemical energy production but it is a primary source of lymph fluid production as well. Therefore, Qigong and Yoga practices can increase the amount of lymph which serves as the fluid carrier for endogenous waste products as well as exogenous pathogenic factors. In this context the metabolizing cells are continually contributing pure H2O into the interstitial spaces.
This water, then, is the vehicle of transport for metabolic by-products into the lymph vessels. From the tissue spaces it is propelled, as lymph, to the immunopotent nodal treatment sites and finally to the elimination organs via the blood. Increasing body movement and activating the breath potentially accelerate O2 absorption which generates more H2O and increases the volume of lymph fluid which enhances the removal of the by products of metabolism and pathogenic factors.
The blood circulatory system has the powerful heart muscle to propel it's fluid. The lymph, however, under the same 14.7 pounds per square inch of gravitational pressure, has no distinct heart in humans. The quest for a "lymph heart" added little to the traditional ideas of propulsion until the mid 1900's when studies of birds and reptiles revealed specific lymph hearts.(43). In humans, however, the propulsion of lymph was found to be carried out by an assembly of several mechanisms. The movement of lymph against gravity is accomplished with the help of a system of vessels that are liberally equipped with one way valves. It was known that the lymph was somehow pumped forward and upward enabling the valves to prevent it from flowing back with gravity.
Even as late as 1941 several important aspects of the lymph heart concept in humans remained obscure.(44) By 1949 spontaneous intrinsic pulsatory contraction of the peripheral lymphatic vessels was demonstrated in humans with a rhythm unassociated with either the heart or the breath.(45,46) This intrinsic contractility mechanism of the peripheral lymphatics was seen by many as the long sought after lymph heart.(40)
The subject of the lymph is complex and very much unsettled. The current literature is crowded with a wide range of questions raised by research. What factors might stimulate the intrinsic contractile mechanism, what regulates lymph protein concentration, what effect does passage through the lymph nodes have on the proliferation of immune cells from within the nodes(47) and what is the nutritive role of the lymph(41) are several such questions.
Due to the excitement over the intrinsic pumping mechanism, the effect on the lymph of one of the classic propulsion mechanisms, the activity of the respiratory apparatus, was eclipsed. The breath, through two mechanisms, has a significant effect on the propulsion of the lymph: 1). aerobic production of water and 2). mechanical pumping of the breath apparatus. These will likely gain recognition as primary components of the multiple features of the lymph heart. A number of additional propulsive mechanisms are initiated by body movement and body posture.
Tentative agreement exists on at least five mechanisms for accomplishing the propulsion of the lymph that are stimulated by Qigong and Yoga practices. These include:
- Aerobic Propulsion
- Intrinsic Smooth Muscle Contraction: Autonomic Propulsion
- Striated Skeletal Muscle: Voluntary Propulsion
- Gravitational Propulsion
- Breath Apparatus: Mechanical Propulsion
Aerobic Propulsion
The aerobic production of lymph contributes to lymph propulsion
by the cellular production of water as a by-product of oxygen metabolism.
The liquid holding capacity of the tissue spaces is naturally limited.
As the limit is reached, the presence of additional lymph drives the excess
into the smooth muscle vessels of the lymphatic system.(39,40,43,47)
In Qigong this mechanism is triggered by the coordination of the breath with gentle movement which increases oxygen demand in the cells. In response there is an increased availability of oxygen which fuels chemical energy productivity and consumption. The resultant contribution of water as a by product increases tissue fluid volume and drives the overflow into the vessels to become lymph.(42)
It is noteworthy here that in Traditional Chinese Medical theory it is taught that the "lungs regulate the water passages"(48). To students from the west this seems quite unusual and unfounded. However, we here can see that the lungs and the breath both produce and circulate the water in the body.
Intrinsic Smooth Muscle Contraction: Autonomic Propulsion
The automatic response of the smooth muscle tissue of the peripheral lymphatic
vessels is to contract when filled and stretched to a certain tolerance.(46)
This moves the lymph along in the vessel with the assistance of the one
way valves in much the same way as the heart moves the blood.(42)
In Qigong and Yoga this mechanism is triggered by the breath's contribution to lymph volume, as well as the elevation of interstitial pressure caused by the postures and the movement of the extremities. In addition, this mechanism may be accelerated or enhanced by the shift of autonomic function in the relaxation state that is a feature of Qigong and Yoga.
Striated Skeletal Muscle: Voluntary Propulsion
Even the slight movement of skeletal muscle in a sedentary
individual propels the lymph in the one way vessels. In an active person
the lymphatic pumping of the striated skeletal muscles is greatly multiplied.
The effect of muscle contraction on lymph is one of the classic explanations
for lymph motion.(40,42) In Qigong and Yoga this mechanism is triggered
by both the mechanical action of the musculature of the breath apparatus
and the action of the skeleton through the relaxation and contraction
of the striated muscles in the moving forms of the practice.
Gravitational Propulsion
Because gravity exerts such a substantial force and because lymph
has so far to climb to get to the thoracic duct's entry into the sub-clavian
vein any inversion of the limbs or even the prone body position allows
for a free flow of lymph unencumbered by the effects of gravity. Elevation
of the lower limbs is often prescribed for health problems characterized
by a pooling of interstitial fluids.
In Qigong and Yoga the thousands of different postures and forms, including lying prone and motionless, often create this mechanical dynamic where the lymph is actually propelled centrally by gravity. In many methods of Qigong there are postures and movements that invert the limbs. In certain walking forms the practitioner is constantly but slowly moving all of the limbs in beautiful circular motions that recurrently activate this mechanism. In Yoga many of the asanas (postures) invert the limbs. In the headstand and shoulderstand, the whole body is inverted.
Breath Apparatus: Mechanical Propulsion
The most powerful of the multiplicity of mechanisms that work together
to form the "lymph heart" is the mechanical action of the breathing
apparatus itself(43). The concentration of lymphoid tissue just above and
just below the diaphragm is many times more dense, and contains greater
fluid volume, than any of the lymphoid tissue at the periphery, or even
in the moderately prolific lymphoid areas of the axilla or groin.(40)
Lymph that has been carried from all over the body accumulates centrally
and is then propelled by the breath/diaphragm in a final rush through
the thoracic lymph duct into the blood at the sub-clavian vein where it
leaves behind its identity as lymph and is transformed into blood serum.(49)
Above the diaphragm the thoracic duct of the lymphatic system is a central collecting vessel. Its size is many times that of a peripheral lymph vessel. Below the diaphragm a substantial dilation of the thoracic duct forms a collecting capsule for lymph, called the "cisterna chyli" (cisterna=cavity, receptacle or reservoir) Chyle is a milky fluid infused with nutritional factors absorbed from the small intestine by the lacteals, which is passed into the circulating blood through the thoracic duct. The fluid that fills the cisterna chyli is a mixture of the nutrient rich chyle from the lacteals and the lymph that carries the metabolic by-products from the tissue of the organs, muscles and glands.
When full inspiration of the breath occurs, the diaphragm drops downward and a tremendous negative pressure is generated in the thoracic cavity. As air rushes into fill this negative pressure the lungs are fully expanded. This compresses the thoracic duct. Due to the one way nature of the valvular system lymph is forced upward into the sub-clavian vein.
Simultaneously, when the diaphragm drops downward on full inspiration it compresses the abdominal and pelvic organs including the cisterna chyli which empties under the pressure. The contents of the lymphoid reservoirs and vessels are forced by the same one way system of valves upward toward the thoracic duct. In research done by Dr. Jack Shields (49) moving X-ray films were used to study subjects in various actions and breath patterns. It was demonstrated that deep inspiration pumps the lymph at a rate that is dramatically increased over average resting inspiration and other activities.
The immunoactive aspect of the lymphatic system is well represented in the literature.(42,44,47,50) The bone marrow, thymus, spleen and lymph nodes participate in the interaction of the lymph and immunity. The composition of the lymph fluid itself includes a number of immune active agents such as lymphocytes and macrophages.(47)
Lymphocytes that exit with the lymph fluid from the nodes come from three sources: 1) inflowing with lymph from the tissues in the peripheral vessels, 2) exchanged from the blood that enters the node's own vascular system and 3) formed by local proliferation in the node itself.(42) Lymphocytes naturally collect within the node, especially when flow is sluggish. Greater numbers proliferate when lymph flow is greater and the numbers circulated out of the node increase with flow volume as well.(42)
Excellent recent research has clearly delineated, localized and quantified the development of specific antibody forming cells in lymph nodes.(50) In addition, it has been found that there are neurotransmitter receptor sites on lymphocytes where they actually interface with neurotransmitters.(51) This demonstrates an important link between neurochemistry and immunity through the medium of the lymph system.
The cerebrospinal fluid (CSF) system has classically been perceived as a closed system. One view held that CSF was actually in an open system that allowed the fluid to flow through the aracnoid villi and into the venous blood. However, by the 1970's it was generally acknowledged that the CSF travels along the cranial and spinal nerves and into the perineural lymphatics.(52)
Some recent research using the microinjection of tracers has suggested several possible pathways for the passage of both the CSF and the cerebral interstitial fluid (CIF) to exit the aracnoid space.(42) By 1985 the flow of CSF and CIF into the lymphatics was well documented.(42) Consideration has even been given to the effects of pressure and posture on this flow(42), both of which are primary effects that are enhanced in Qigong and Yoga/Pranayama practice.
The presence of CSF in the lymphatic system and the presence of neurotransmitter receptors on immune cells(53) suggests a powerful association between neurotransmitters and immune function in the reticuloendothelial system. While the effect of Qigong and Yoga/Pranayama on this mechanism is not clearly defined, it is likely that it occurs through lymph propulsion as has been discussed. Research to quantify and delineate this aspect of the lymph system and explore the action of lymph and CSF as a transport system for specific neurochemicals is clearly a priority.
5. Nutritive (trophic) Function
The importance of a broad availability of nutritional factors to the tissues is fully accepted. However, the role of the lymphatic system in this activity was barely understood before 1972.(41) The original findings of Assellius in dogs revealed the route of absorption of nutrients from the small intestine via the lacteals.(40) The effect of the breath apparatus through the action of the diaphragm, during deep inspiration, on the cysterna chyli and the small intestine may enhance the rate or effectiveness of nutrient absorption. This may be an especially important mechanism in the absorption of nutritional factors and the delivery of the pharmacologic potential of herbal formulas that are commonly used in both the Chinese and Indian traditional medical systems.
In addition, free extracellular proteins participate in lymph fluid and as plasma proteins in the blood. They carry constituent amino acids that may be utilized by the tissues. These may become conjugated proteins which carry essential minerals, fats, carbohydrates and enzymes to their respective destinies.(41) The clarification and understanding of the trophic function of the lymph suggests a simple but profound effect of the enhanced lymph volume and flow rate activated by Qigong and Yoga/Pranayama.
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