Читать книгу Compendium of Dr. Vodder's Manual Lymph Drainage - Renato Kasseroller - Страница 9
Оглавление1 The Foundations of Manual Lymph Drainage in Chemistry, Physics, Physiology and Histology
1.1 The Basics of Manual Lymph Drainage's Mode of Operation
1.1.1 The Autonomic Nervous System
The autonomic nervous system is made up of two subsystems: the sympathetic and the parasympathetic. The active sympathetic energizes us, while the parasympathetic sees to relaxation, resting, recuperation. One can find the fibers of the parasympathetic system in all parts of the human body, including connective tissue.
Normally, the reactive state is in equilibrium. Hectic activity, stress and other external factors increase sympathicotonia. This leads to disharmony, which results in negative states, complaints and ailments. The autonomic nervous system's activity is not subject to our will and cannot be directly influenced by us. Consciousness resides in the cerebral cortex, whereas the unconscious is found in the autonomic centers in the spinal cord and other parts of the brain.
There are two kinds of cells in the central nervous system. The actual organ cells are the ganglion cells, with the glial cells forming the supportive framework. They actively take in nutrients from the blood stream and transport them through their cell bodies to the ganglion cells. Because of their specialized construction, they only take up certain specific substances from the blood and pass them on; this is known as the blood-brain barrier.
Transmission of stimuli takes place via the ganglion cells. Simplifying somewhat, they consist of cell membrane, protoplasm, nucleus, endoplasmic reticulum (protein synthesis), Golgi body and numerous mitochondria for energy production. These structures are an integral part of the cell body.
In addition, a ganglion cell has one or two long extensions (axons) and numerous shorter ones (dendrites).
Fig. 1: Functional diagram of a ganglion cell
A peripheral nerve is composed of a number of axons bundled together. Myelinated nerves are coated with a myelin sheath. Axons can be low-myelin, amyelinic or high-myelin. This is decisive for stimulus quality and propagation speed. Motor and sensory tracts consist of myelinated axons, the nerve tracts are amyelinic.The axon terminates in club-shaped expansions called synaptic knobs, which are surrounded by a presynaptic membrane. The impulse receptors are located in the dendrites, from which the impulses are transmitted to the synaptic knobs. The variously-constructed ganglion cells determine the type of impulse and its transmission. The entire unit is also called the axon. Impulse transmission in this axon is an electrical process. Axon length varies, and can exceed a yard in length.
The synaptic knobs (presynaptic portion) are in indirect contact with the dendrites of the next nerve cell (postsynaptic cell), separated by the synaptic cleft, or synapse. Here various potentials are formed of a chemical or electrical nature. The synapses are variously formed, depending on which part of the nervous system they belong to. Synaptic transmission is sometimes a chemical process, sometimes electrical, sometimes both. The principal chemical neurotransmitters are acetylcholine, noradrenaline, adrenaline and - in the CNS - dopamine and serotonin. Synapses can be inhibitory or excitatory.
Impulse transmission in the axons is strictly a one-way process. Differences in construction and transmission mechanism determine the various effects at the target organs.
We distinguish between stimulating or excitatory synapses and restraining or inhibitory synapses. Stimulation of the receptors is likewise effected by many different kinds of stimuli.
Thus, there are photoreceptors, chemoreceptors, thermoreceptors, pain receptors and mechanoreceptors, depending on whether they are activated by light, chemical or temperature stimuli, or mechanical influences such as stroking or jabbing, etc. Since more and more receptors are affected by a (continuing) stimulus, this makes possible a great variety of reactions. Depending on the kind of stimulus, the impulses in the CNS are either transmitted to higher centers (e. g. pain sensations) or processed in autonomic centers, which can then trigger involuntary reactions (e.g. reddening of the skin). This variety in the various component units accounts for the manifold impulse types. [2, 32]
1.1.2 Reflex Arc
A reflex is a response to a stimulus. Simply put, the stimulus is received by the axon via the receptor and passed on to the reflex center, where it is re-routed. Another axon then transmits a fresh impulse to the target organ. A reflex arc does not necessarily consist of just two neurons. Various neurons form a network of lateral interconnections. Because of this, a stimulus can end up at both an inhibitory as well as an excitatory synapse. A pain stimulus secondarily triggers swelling and reddening. The preceding gives just a hint of the complexity of reflex arcs. Reflexes can also be accompanied by emotional reactions, which once again illustrates the complexity of the excitation.
Reflexes are categorized into various reflex groups, such as fight-or-flight or affection reflexes. Manual Lymph Drainage triggers pleasure reflexes which give the patient a feeling of well-being. Basal muscular activity is reduced, which has a relaxing effect.
The activation of an inhibitory cell can dampen or even extinguish a parallel excitatory process. There are receptors that react to a stimulus for as long as the stimulus persists (pain stimulus), whereas others only react to a change in some aspect of the stimulus (mechanoreceptors). The varying pressure of Manual Lymph Drainage is first transmitted to the CNS as a touch sensation, but other (inhibitory) neurons are also activated via collateral connections. These can have a moderating effect on pain situations. Every stimulus should be regarded as a complex, which helps make the various possible reactions comprehensible.
The fact that nerve tracts get re-routed in the spinal cord explains why, in most indications, treatment of the opposite (contralateral) side is also effective.
See Fig. 2.
1.1.3 The Immune System
This is man's defensive system, which not only attacks infectious germs, but also foreign (non-self) substances, especially proteins. However, defensive mechanisms can also develop against inorganic materials. The human immune system distinguishes between [non-self] and [self] signals which are carried by protein bodies, polysaccharides and lipids. The human organism recognizes its own proteins, namely the ones present in the body at the time of birth. Under special pathological conditions, it can come about that the body identifies its own tissue as non-self and produces antibodies against it; this is known as an autoallergic disease.
The immune system works with two mechanisms: humoral immunity, for which certain proteins (gamma globulins) are responsible; and cellular immunity, which is carried out by certain cells (lymphocytes, plasma cells, macrophages).
1.1.3.1 Humoral Immunity
Antigens are the various foreign substances which can trigger an immune reaction. They react specifically with antibodies or sensitized lymphocytes. Antigens can be foreign protein bodies, polysaccharide-polypeptide complexes (e. g. the blood-type agglutinogens on the surfaces of erythrocytes), but also low-molecular-weight chemical compounds bound, for example, to albumin. Antibodies are present in all bodily fluids: blood, lymph, connective tissue. They are produced primarily in the lymph nodes. Chemically, they are globulins, divided into five major groups:
Fig. 2: Reflex arc schematic, with an inhibitory neuron in the circuit
Immunoglobulin A (IgA) - Used primarily to fight viruses, bacteria and altered forms of the body's own cells. It is formed from plasma cells and is mostly found in the mucous membranes. The highest concentrations are found in saliva, lachrymal fluid, colostrum, mother's milk and gastrointestinal and urogenital excretory products. Its function is to confront antigens at their point of entry into the body.
Immunoglobulin G (IgG) - Also known as gamma globulin, it is present in the greatest amounts and is most concentrated in the plasma. It is a part of most humoral immune reactions.
Immunoglobulin M (IgM) - This is the largest immunoglobulin molecule. In humoral defense reactions, it is the first one to be produced. IgA and IgG come later but are effective over a longer period of time.
Immunoglobulin D (IgD) - Present only in low concentrations in the serum, it is mostly to be found on the cell membranes of the circulating B lymphocytes.
Immunoglobulin E (IgE) - It, too, is present in relatively low concentration in the serum; its main involvement is with allergic reactions.
Immunity weakens with time, but it can be reinvigorated by renewed contact with an antigen.
Lymphostasis can - for whatever reasons - restrict the transport of immunoglobulins, which has a deleterious effect on the defensive system. Immunoglobulins are stored in various kinds of cell systems (plasma cells, lymphocytes, macrophages, thymus, spleen) and in the connective tissue.
The humoral defense system begins to develop in the third month in the Peyer's patches and similar structures in the intestinal tract. The antibodies react with antigens and form complexes which are in turn eliminated by cellular elements. At the same time, all defense mechanisms activate proteolytic enzyme systems and release histamine, which can be found in all allergic and pain reactions as they develop. Nonspecific humoral immunity is effected by interferons and pyrogens. [3, 4, 5]
1.1.3.2 Cellular Immunity
Numerous human cells are capable of phagocytosis. These cells can ingest foreign bodies and disease germs and break them down enzy-matically.
Besides these nonspecific defense cells, there are others that enable the body to mount a specific defense as well. They are called lymphocytes and are produced in the bone marrow. They are especially concentrated in the lymph nodes, spleen and Peyer's patches of the small intestine. During their maturation, they are equipped for immunological defense in the thymus. When a lymphocyte comes in contact with an antigen, it can be sensitized to it - i. e., all of its descendant cells will carry an antibody specific to that antigen.
The development of cellular immunity in the thymus takes place earlier than that of the humoral defense system, namely in the embryonic stage.
Not all lymphocytes take this developmental route. One kind, the T lymphocytes, are to some extent also able to ward off and destroy tumor cells. The T lymphocytes are responsible for direct cellular defense.
The B lymphocytes comprise the second group. These carry the immunoglobulins on their surface. However, the two lymphocyte types cannot be distinguished morphologically; the distinction is purely functional, and visible only under the electron microscope.
In the course of cell division, the lymphocyte becomes a plasma cell, which then produces immunoglobulins.
If antibody formation does not take place when an antigen invades the body, this is called immune tolerance. This is a sensible arrangement, since not every invader is pathogenic enough to warrant initiating a disease state. Thus, the individual organism is capable of deciding for itself.
Manual Lymph Drainage supports immune reactivity by stimulating lymph flow in order to drive the disease-causing substances more quickly into the lymph nodes, where they can be neutralized. Successfully warding off a microbe-based infection does not depend on its pathogenicity, but rather primarily on the reactive situation, the resistance of the affected organ system. Resistance is the overall defensive capability, and is not antigen-specific, but is influenced by genetic and general conditions (diet, stress). This is definitely aided and promoted by Manual Lymph Drainage. [3, 6]
1.2 Connective Tissue
The human organism consists on the one hand of symplasms and of fluid compartments on the other, which in turn have a fluid and a cellular component. Every cell then has its own specific share of fluids. Thus, we distinguish between extracellular fluid volume (ECF), intracellular fluid volume (ICF) and interstitial fluid volume. Since the human organism is partly an open system, there is an exchange of numerous components among the individual compartments, whereby various forces work in a regulatory capacity.
Of primary importance for Manual Lymph Drainage are the fluids of the blood, the lymph and organ connective tissue. Besides the hard supporting substances bone and cartilage and taut connective tissue such as tendons, fascia and ligaments, there is loose connective tissue, which is richer in cells than the other. It combines cells into tissue groups, tissue into organs, organs into an organism. The vascular structures of blood capillaries are integrated with connective tissue, as well as lymph capillaries and the nerve fibers of the autonomic nervous system. Connective tissue is made up of cells, fibers, the ground substance and fatty tissue. It is an organ.
1.2.1 The Cellular Portion of the Connective Tissue
The cellular portion is composed of mobile and fixed cells. The fixed cells are the fibrocytes or their precursors, the fibroblasts. Fibroblasts are much more active than fibrocytes and possess various differentiation options. They form the ground substance and the three kinds of connective tissue fibrils. They exude tropocollagen (a collagen precursor) in soluble form into their environment. Collagen fibrils, the basic structure of connective tissue, form by aggregation onto these molecules (fibrous structure).
The mobile cells are introduced into connective tissue via the blood. Mast cells are present everywhere in loose connective tissue, especially in the immediate vicinity of the vessels. This cell type contains copious amounts of histamine, which is released by the cell during inflammatory processes. This dilates the small vessels and increases their permeability. In addition, histamine stimulates the pain receptors in the tissue. The mast cells can carry immunoglobulin E. Histamine is also released in antigen-antibody reactions - which gives rise to the familiar symptoms of the allergic reaction.
Granulocytes: In connective tissue, there are neutrophilic and eosinophilic granulocytes. The latter turn up primarily during allergic reactions in the tissue. They are able to take up antigen-antibody complexes and break them down. The neutrophilic granulocytes appear during inflammatory reactions and are capable of phagocytosis.
Lymphocytes: This cell type (and the plasma cell, too) appears in strength in cases of immunological reactions in the tissue.
Histiocytes: These cells are related to the monocytes of the blood. They are especially numerous around fresh edemas, and are responsible for the proteolytic decomposition of proteins in the tissue. These smaller tissue components can then be carried off by the venous limb of the blood's vascular system.
Phagocytosis is the ability of a cell to ingest and digest foreign cells or cell fragments. [1]
1.2.2 Fibers
Fibrous tissue is differentiated, depending on its location, into collagen fibers, reticulin fibers and elastic fibers. They have a common origin in all having been formed from fibroblasts. A number of polypeptide chains are combined to make a tropocollagen molecule.
Collagen fibers: Tropocollagen molecules are laid together to create protofibrils, which are then joined to form a microfibril. The filaments lie in the interior of these microfibrils in an amorphous ground substance. The ground substance also functions as a lubricant and additionally allows the collagen fibrils to bend. Collagen fibers are a tensile element and are very inelastic. They are found in bones, cartilage, tendons and fascia, as well as in the subcutis. They are also combined with elastic fibers, protecting the elastic fibers from overextension and tearing.
Reticulin fibers: These are similar to collagen fibers, but much more finely formed. They are to be found in numerous organs as a connection to parenchymal cells (liver, kidney), but also in loose connective tissue. In vascular basement membranes, they form a fibrous network.
Elastic fibers: these consist of fibrillary scleroproteins and always form a network. They age over time, gradually losing elasticity. They are also subject to hysteresis, which means that, after being stretched, there is a delay before they return to their original length. After a certain age, or after longer-term extension, they can no longer return to their original state.
Elastic fiber networks can be found in the skin, vessels, lungs, elastic cartilage and in the capsules of various organs. Pregnancy stretch marks are a result of overextension and tearing of elastic and collagen fiber networks. [7]
1.2.3 Ground Substance
The ground substance is also formed from fibroblasts. It is the transmigration area of the individual nutritive substances from capillary to cell. Besides water, it contains electrolytes, amino acids, peptides, hormones, vitamins and various albuminous substances. Proteins are present in a saline state. The ground substance behaves thixotropically, i.e. it reacts to temperature and mechanical shear by liquefying. This thixotropy gives the system a degree of inertia which needs to be taken into account in Manual Lymph Drainage. The macromolecules of this substance are linked together into network structures, which can then be dissolved by heat and motion. Rapid application of pressure with inadequate warm-up can tear these substances (muscle tears caused by athletic exertion without prior warm-up).
But the proteins can also bind to other substances such as mucopolysaccharides and hyaluronic acid. Hyaluronic acid acts as a mortar material, which also binds the filaments on the basement membrane of the lymph capillaries. Hyaluronidase, an enzyme also found in connective tissue, breaks down hyaluronic acid, thus liquefying the ground substance. Normally, there is a balanced relationship between continuous breakdown and re-synthesis of this substance.
Like proteins, mucopolysaccharides also have a great affinity for water; they are present in the ground substance in a gel state.
In addition, axons of the autonomic nervous system run through the ground substance, thus establishing a connection with all other regions of the human body.
Manual Lymph Drainage is a form of massage adapted to this kind of tissue, normalizing the function and composition of connective tissue. Fluids and dissolved substances can be shifted about extravascularly in any direction in the connective tissue.
The ground substance is the connective tissue's space-filling, semi-gelatinous, semi-fluid mortar mass.
Materials transport, which carries nutritive substances from the blood capillaries to the cells and waste and decomposition products back from the cells to the capillaries, takes place via the connective tissue. The connective tissue cells contain all the necessary enzymes for the production of collagen, elastin and polysaccharide proteins. They thus need to be properly nourished, a process in which the ground substance is involved. The ground substance is also the environment of the parenchymal cells. [8]
1.2.4 Adipose Tissue
Adipose tissue is simply another form of connective tissue. Fat is present in liquid form in the fat cells. The fat cells are fixed in place by elastic and collagen fibers.
A functional distinction is made between buffer fat and storage fat. Buffer fat has a static function and is not at first broken down for nutrient purposes during times of reduced food intake. Storage fat is found in subcutaneous tissue, the greater momentum and the peritoneum of the large intestine. It also protects the organism from hypothermia. This depot stores excess calories and makes them available to the organism in times of low nutritional intake.
Connective tissue regulates energetic processes, as well as physio-chemical and electrical sequences of events. Unconscious and undifferentiated vital functions such as water, mineral and energy balance take place in the connective tissue. As a storage depot, it takes up salts, vitamins, fats, water and hormones. The human body's general nonspecific defensive measures are based in connective tissue.
It is the physical nutrient depot for fats in the fat cells and for carbohydrates in the polysaccharides. This storage function of the polysaccharides is significantly greater than that of glycogen in the liver.
Water is present in the blood and lymph systems and is hydrodynami-cally active in the connective tissue. But it is also stored inactively and bound by the fibrils of mucopolysaccharide molecules.
Connective tissue has tremendous regenerative capacity. When organ tissue dies, fibroblasts multiply and function as stopgaps. Vitamins and minerals are also stored in connective tissue. Connective tissue is distributed throughout the entire organism and can thus fulfill its double role as transport medium and storage depot for all the body's cells. Thus, the necessary nutrients are available to all cells at all times. If metabolic waste products accumulate, the tissue's function is impaired. In the early stages, this leads to cosmetic defects; in more advanced cases, it causes pathological health disorders.
1.3 Dynamic Tissue: Blood, Lymph
The human body is two-thirds fluid. Water content is 60 % of body weight, plus or minus a few percentage points depending on age and gender. The fluids are distributed throughout various regions of the body.
Blood, for its part, has a liquid and a cellular component, and makes up about 6 % of body weight.
The extracellular fluid volume consists of the transcellular region (composed of cerebrospinal fluid, joint fluid and glandular secretions, comprising about 20 % of body weight) and an additional 20 % interstitial component.
The intracellular fluid volume, found in the individual cells, makes up about 50 % of human body weight.
These figures are all approximate, since it is very difficult to measure the individual components accurately, due to the continual exchange taking place among them.
Nutrients can only be transported in a fluid environment. To a certain extent, the state of the transport system is a mirror of our health. All substances transported by the blood must traverse the connective tissue to get to the cells; contrariwise, the cell's waste products are sent for elimination to the blood or lymph via the connective tissue. Manual Lymph Drainage works directly with and on this transport mechanism.
1.3.1 The Cardiovascular System
Starting in the left chamber of the heart, blood is pumped through the aorta, then via arteries and arterioles to the precapillaries and finally the capillaries in the periphery. The capillary system is the transition region between the arterial and the venous system. From the venous capillaries, the blood goes to the venoles and then the veins and finally, via many intermediate destinations, to the heart's right chamber.
This is now where the “small” circulatory cycle begins, as the right chamber of the heart pumps the blood into the lungs. As in the capillaries, oxygen exchange takes place in the pulmonary alveoles, as C02 is released and fresh oxygen is taken up. More precisely, oxygen reacts with hemoglobin to form oxyhemoglobin, which is transported to the capillaries. There, the oxygen is released and diffuses into the tissues. C02, on the other hand, is taken into the watery portion of the blood as a dissolved gas. Thus, the arteries are the inflow to the tissues, while the veins are the outflow of this transport system.
But the veins carry off more than just oxygen-poor blood from the connective tissue, such as low-molecular-weight substances, salts, gases and minerals.
We also possess another drainage system, namely the lymphatic system, in which the lymph-obligatory load is carried away. These are large-molecule substances such as proteins and large-molecular fats, as well as immobile cells, cellular detritus, waste products, bacteria, viruses, excess water and inorganic materials.
1.3.2 The Blood
The fluid part of the blood, the plasma, contains dissolved ions, inorganic and organic molecules, which either are transported to the various organs or serve as a means of transportation for yet other substances. The plasma proteins include albumin, globulin and fibrinogen. The globulins are subdivided into alpha, beta and gamma globulins. The gamma globulins are responsible for the immune reactions, the alpha and beta globulins primarily for the transport of other substances.
In the plasma, protein substances are present mostly as anions, representing about a sixth of the plasma's buffer capacity.
They exert a pressure on the capillary barrier of about 25 mm Hg, where the permeability of the walls is very low for plasma proteins. On the other hand, in the venous part, water is removed from the tissues and brought back into circulation via this pressure.
Albumin and fibrinogen are produced in the liver, the globulins for the most part in the spleen and lymph nodes.
But the approximately 5.5 liters [6 quarts] of blood in an adult body are not all fluid; there are also the red and white corpuscles.
1.3.2.1 The Red Blood Count
Erythrocytes measure about 7.5 u and thus have a larger diameter than the capillaries, which means that they must be pushed through the capillaries, since they are not capable of motion on their own. Their life span is about 120 days. Males have about 5 million of them, females somewhat fewer. Their most important function is transporting hemoglobin, which in its turn transports oxygen. They shrink in hypertonic solutions and swell up in hypotonic ones, at which point hemoglobin can be released. They are manufactured in the bone marrow.
Thrombocytes are small blood platelets with a diameter of about 2 p. They originate in the bone marrow's megakaryocytes, contain numerous hormones and carry the clotting factors.
Fig. 3a: The blood's primary physiological cell types
1.3.2.2 White Blood Count
The white corpuscles (leukocytes) only spend part of their life in the blood. They spend much more time in the bone marrow, lymphatic tissue or connective tissue. Morphologically, there are various forms:
• Granulocytes: neutrophils, basophils, eosinophils
• Lymphocytes, plasma cells
• Monocytes
Neutrophilic granulocytes: These originate in the bone marrow and have a life span of about 30 hours. Normally 55–60 % of these cells are found in the blood. They are capable of phagocytosis and are attracted to bacteria and general inflammatory reactions, leaving the bloodstream through the vessel wall at the site of the disturbance. These are the nonspecific cellular defense cells. They carry enzymes which enable them to perform phagocytosis, i. e., they can ingest and digest foreign bodies. They can penetrate bodily membranes.
Eosinophilic granulocytes: These comprise about 2–3 % of the white blood count. Their numbers increase during allergies, and they can ingest and digest antigen-antibody complexes.
Basophilic granulocytes: These are rich in histamine and heparin (an anticoagulant substance). They make up about 1 % of the white blood count.
Lymphocytes: These measure about 8 u and make up about 30 % of the white blood count. Depending on their function, they have a life span of from a few days to a year. They have the most varied tasks in the immune reactions. They are produced in the bone marrow.
They also come in different sizes depending on function. During inflammatory reactions, their numbers increase in the white blood count.
They are sensitized by contact with antigens and become capable of dividing. This gives rises to a specific defense, a characteristic which is passed on to all descendant cells. A functional distinction is made between B lymphocytes and T lymphocytes.
B lymphocytes appear clumped together as lymph follicles in the lymph nodes. In the context of confrontations with antigens, there is a distinction made between primary and secondary follicles.
T lymphocytes are individually distributed throughout the lymph nodes. They can remain there for several days, but not for more than 24 hours in the blood. The difference between B and T lymphocytes can only be perceived using an electron microscope.
Plasma cells: These make up only 1 % of the blood, but are quite numerous in lymph nodes and tissue. Morphologically, they are quite similar to lymphocytes. Their cell bodies include vacuoles containing gamma globulin, which they can release into the blood plasma.
Monocytes: These have a diameter of 20 u and are thus larger than the others mentioned above. They are also capable of phagocytosis, in addition to which they can move about like amoebas.
1.4 Materials Transport
The transport of individual nutrients from the blood to the cells makes use of various mechanisms. This is due to the varied composition of the fluids in their respective compartments. The individual substances are present in varied concentrations; the quantity of molecules and their electric charge also varies.
1.4.1 Diffusion
Diffusion is the main factor in water distribution. The particles (molecules, ions) of a gas or dissolved substance tend, due to their own motion, to fill the available space. They spread out from locations of higher concentration to those of lower concentration, eventually attaining an even distribution. Of course, there is movement in the opposite direction as well, but in the end, the average movement toward locations of lower concentration prevails. The magnitude of this tendency is proportional to the concentration differential of a given substance between two locations.
However, the diffusion of ions depends on their electrical charge as well. In the presence of a partial differential between two locations in a solution, positively-charged ions drift towards areas of higher negative charge, whereas negative ions drift in the opposite direction.
The engine of diffusion is the thermal motion of molecules. In the body, diffusion takes place not only within fluid compartments, but also from one compartment to another, as long as the intervening barrier is permeable to the diffusing substance. Diffusion is temperature-dependent, with higher temperatures accelerating diffusion.
Fig. 3b: The blood's primary physiological cells
An additional factor is particle size: the larger the particle, the slower the diffusion rate. Diffusion time is proportional to the square of the distance, which is why it is only effective over short distances. Oxygen transport from the capillaries to the cells and C02 transport in the opposite direction both function according to this principle. [2]
1.4.2 Filtration
Filtration is when a fluid is forced through a membrane by a pressure differential between the two sides of the membrane. The amount filtered is proportional to the pressure differential and the surface area of the filter. The molecules to be filtered must be smaller than the membrane pores. Small particles filter through capillary walls into tissues when the hydrostatic pressure in the blood vessels is greater than that in the extracellular fluid volume.
But since we are always dealing here with complexly structured compartments, there is always some resorption. Fluids and small molecular substances thus work their way through capillary walls into tissues and vice-versa. The amount of filtrate depends on the surface area and permeability of the capillary walls, and on the blood capillary pressure.
The sum total filtrate amount in the body is almost insignificant relative to diffusion. [2]
1.4.3 Osmosis
If a semipermeable membrane separates two solutions of differing concentration, then the solvent will drift in the direction of higher concentration. The membrane is impermeable to the higher solvent concentration. This drift can be prevented by means of pressure on the more highly concentrated solution. The amount of pressure needed to bring the osmotic drift to a stop is known as the effective osmotic pressure. Osmosis is the water attraction of salts and sugars, oncosis the water uptake power of proteins. The current term for the latter is now colloid osmosis. The cause of this phenomenon lies in the activity of the solvent, which is reduced by dissolving a substance in a solvent. It is necessary that the membrane be permeable for the solvent but not the solute.
Osmotic pressure
N = number of particles, R = the gas constant, T = temperature, V = volume
Ionization of individual electrolytes also influences the number of actually available osmotically effective particles. The term “tonicity” serves to indicate the effective osmotic pressure of a solution relative to the plasma. If the pressures are equal, it is termed isotonic; hypertonic refers to a higher and hypotonic to a lower pressure.
All of these transport processes are passive; the particles involved move “downhill”. However, in many situations it is necessary to move “uphill” toward a region of higher concentration, or against osmotic pressure or an electrical gradient. This is known as active transport, and requires energy from cellular metabolism.
1.4.4 Homeostasis
The interstitial part of the extracellular fluid is the environment of body cells. Normal functioning of the cells is dependent on the constancy of this fluid. There are numerous physiological regulatory mechanisms whose purpose is to restore normal conditions after a disturbance. Most of these mechanisms work on the feedback principle. Numerous sensors located all over the body register deviations from the norm and trigger compensation mechanisms in order to return the system to normal. [1, 9]
Summarizing, one can say - simplifying somewhat - that the following forces are active in transporting materials out of the blood: the blood pressure in the capillaries and the oncotic suction of the tissue proteins exert the filtering force; the tissue pressure and the oncotic suction of blood proteins exert the resorptive force. In the current literature, oncotic suction is designated as colloidal osmotic pressure. Under physiological conditions, this generates an equilibrium in the region of the terminal vessels, i. e. the perfusion forces in the capillaries are the same in both directions. This was ascertained around the turn of the century by the physiologist Starling.
However, one should always keep in mind that, due to the complexity of the feedback mechanisms, the alteration of one factor can change numerous other substances and conditions on a continuous basis, and that the various bodily regions will each react differently. If the filter forces outweigh the resorptive forces, then a portion of the filtrate will not be returned to the capillaries, but will instead remain in the tissues.
From there it can be taken up by the lymphatic system, which can carry it on. For Manual Lymph Drainage to succeed, it is necessary to know (among other things) whether and to what degree resorption at the venous limb of the blood capillaries can be strengthened.
In this context, the following factors are influential: the blood pressure exerts a force on the vessel walls from within and.thus keeps the vessel filled out. In this manner, fluid is forced - i. e. filtered - through the permeable vessel walls. The plasma's protein components bind water and thereby also fill the vessel. However, this water attraction also works through the capillaries and thus draws water out of the tissues. Thus, besides filtration, resorption takes place at the same time. But since the other side of the capillary walls, the connective tissue, also contains protein substances, additional water molecules are induced to migrate out of the capillaries. This is yet another filtration factor. The more proteins and water in the tissues, the greater the pressure exerted on the vessels. This tissue pressure acts as a compensatory force on the capillaries and thus induces resorption. The pressure of any manual massage works with this tissue pressure, which compresses and re-sorbs.
The most important prerequisite for filtration and resorption is flow in the vessels. If a vessel is pinched shut by external pressure, then the flow stops. The region around the vessel then suffers from a lack of nutrients, and waste products pile up. If the external pressure lets up, the capillary opens up again and blood flow resumes, with elevated pressure at first - which results in increased filtration. Since the blood pressure would also have risen in the venous part, resorption is reduced. The filtering arterial power limb of the capillaries becomes longer, the resorbing venous limb of the capillaries shorter. The correct -i.e. the ideal - massage pressure for Manual Lymph Drainage works together with the tissue pressure and thus has a resorbing effect. Increasing the massage pressure thus sets clear limits to the effect(iveness) of the massage. The best resorption results are obtained by that pressure which does not quite cause compression (of the vessels).
Fig. 4: Starling's equilibrium
The construction of the vessel walls, their permeability, as well as the size relationship of the respective arterial and venous capillary limbs -all of these also influence the relationship between resorption and filtration.
Current scientific terminology refers to effective filtration pressure, which consists of the blood pressure in the capillaries minus the tissue pressure, and effective colloidal osmotic pressure consisting of the colloidal osmotic pressure in the blood minus that in the tissues. If the effective filtration pressure exceeds the effective colloidal osmotic pressure, then this leads to build-up of fluid in the tissues, the net ultra-filtrate is elevated, leading to what is termed an elevated lymph-time-volume. The lymph-obligatory load is increased.
But in addition to filtration, diffusion and osmosis, there is the factor of active transport or proteins and other substances. Only the smaller proteins (albumin) can seep through the large pores of the capillaries and thus end up in the tissues.
Active transport takes place via the vascular endothelial cells. The membrane of the endothelial cell everts itself into the vessel's lumen and takes up the protein molecule: it is enclosed in a vesicle. This vesicle drifts through the cell and releases the protein on the far side. In this manner, the protein moves from blood to tissue. This process is called cytopempsis. When other substances are transported through cells in this manner, it is termed pinocytosis. However, since there is always a drive toward homeostasis, protein is able to be transported back into the blood and the lymph by this route as well. In this form of cytopempsis, the molecular structure of the protein is not altered. This is a physiological process, an active performance on the part of the endothelial cell.
See Fig. 5.
But proteins can also enter the inner part of the cell and permeate through the plasma, whereby their molecular structure is altered by being changed into water-insoluble mucopolysaccharides and excreted onto the basement membrane. They can be stored there, or passed on to the connective tissue, after undergoing yet another structural alteration.
The endothelial cells have a special sensitivity to the body's own substances with high blood level, but also to foreign substances. In physiological permeation, protein binds with the basement membrane, causing it to become thicker and changing its permeability. The basement membrane shifts outward. On the outer wall, the water-insoluble mucopolysaccharide complex is restructured by the epithelial cell into water-soluble protein and passed on to the tissues. The outward shifting of the basement membrane also displaces the stored protein. Foreign protein substances are turned into euprotein and returned to the blood or turned into mucopolysaccharide complexes and deposited on the basement membrane.
Under special circumstances, the endothelium and epithelium will not be able to metabolize or restructure all of the protein. The surplus is then deposited on the basement membrane as well, which can cause pathological reactions. Thus, the basement membrane is, along with the connective tissue, an extra protein depot. It is considered pathological for the basement membrane to swell to more than 1400 A (Angstrom units) as a result of protein deposition. Optimal filtration and diffusion becomes disrupted. To ensure cellular nutrition, regulating forces spring into action. Blood pressure rises reflexively to guarantee diffusion and filtration.
The basement membrane's permeability to nutrient substances depends on how swollen it is, which in turn depends on the acid-base balance.
When the basement membrane protein depot is overstuffed with protein, the next step is a reflux of protein into the bloodstream. The proteins can be resorbed by the vascular endothelium and excreted at the intima of the arteries. This in part explains the genesis of arteriosclerosis.
Fig. 5: Cytopempsis-pinocytosis
Normally, after eating, the nutrient substances are driven through the blood capillaries and the basement membrane into the connective tissue by the high diffusion pressure which is generated by the high level of nutrients in the blood - thus satisfying, for the time being, the cell's nutritional requirements.
Excess nutrients are stored in connective tissue depots: protein in collagen and mucopolysaccharides, glucose in the sugar part of mucopolysaccharides, fat in fat cells, water in mucopolysaccharide molecules. By this means, the tissue becomes thicker in various spots. As long as the basement membrane is healthy, all nutrients for cell supply and storage go through it. The overfed parts may get thicker, but they are still healthy. This can turn pathological with an unbalanced diet, especially an excess of animal protein, since the basement membrane eventually becomes overtaxed.
The basement membrane gets thicker if protein deposits become excessive, which causes its permeability to decline.
Protein molecules leave the bloodstream in 24 to 48 hours, wind up in the tissues and are returned to the blood via the lymphatic system. The most important transport protein is albumin, with a molecular size of about 70 A. It transports vitamins, enzymes, hormones and metals. The gamma globulins, with a molecular size of over 100 A, also travel this route.
Plasma protein circulation is a transport mechanism for vital substances to the cells and for metabolic products from the cells. This protein cycle takes place in part via the lymphatic system, since some of it cannot get into the venous limb due to size. Therefore, protein metabolism requires a functioning lymphatic system. If proteins stay in the connective tissue too long because the transport system is not working, then it alters its molecular structure, giving rise to a new pathological factor.
The volume of extracellular fluid depends on the total amount of osmotically active substances. The most important factor here is the acid-base balance, particularly the extracellular fluid's sodium content. Numerically, the sodium ion and the chlorine ion are the dominant osmotically active mineral substances.
Regulating the sodium ion concentration takes place via a number of mechanisms. The most important organ in this is probably the kidney, but always working in concert with other organs.
The lymphatic system comes to the rescue by carrying off substances in order to maintain (or reestablish) the optimal state. However, in many pathological situations, this may not be enough. The activity of the lymphatic system can carry off substances, thus maintaining capillary permeability - or improving it before damage can occur or before other regulatory mechanisms are forced to spring into action. [2, 10]
