It induces thermal change in the body.This event is a thermal discomfort,a thermal eustress.This heat stress precipitates a decreases in cardiac output which sends massages to medullary Cerebro vascular control center which in turn effect muscle and skin vasoconstriction.This increases in the internal circulation by which the cardiac output is optimized.Thermal comfort rests primarily upon the following six factors- air velocity,air humidity,mean rediant heat, metabolism, insulation and air temperature.These thermal comfort factors are individually or severely manipulated Swedan to effect theo thermal eustress .The conduction of heat depends upon the calorific value of the material used.
FOMANTATION and SUDATION:
Are anscient methods of ward off pain or atleast to lessen the suffering due to pain.Application of heat by various methods at a diseased site or through the entire body such that it causes perspiration is called sweda vidhi,in Ayurveda.Many of means and methods.Heat canbe applied directly or indirectly; it can be applied dry or moist; with or without instruments.
Heat is a form of energy associated with chaotic ionic movement,the temperature of a material being an index of its internal energy.It expressed in kilojules,but we usually expressed in centigrade. The rate of heat transfer is indicated in Watts .Heat effects melting, dissolution, evaporation,drying and sterilization of an area from microbes etc in the. Ody.
Heat is transferred by one of the following methods- conduction, convection and radiation.Heat is conducted in solids, liquids and gases. Gases are better conductors at high temperature than most liquid except water.Mettalic solida are good conductors than non metaliic because due to heat transfer electron movement is generally greater in the former than in the later due to vibration in the latticein conduction molecules donating the heat energy will gradually cool down,but that recieving heat energy will vibrate to a greater extent and increase in temperature.Heat transfer by conversation is seen in fluids only,set up as convection currents between differential densities.Heat transfer by radiation can best be understood by energy emitted by the sun, being transmitted in the form of electromagnetic waves.
These waves can be reflected
, Transmitted and can be absorbed.
1) duration of heat,
2) calorific value of material used
3) medium of heat transfer
The medium is selected depends upon the calorific value of material used as per ability to heat transfer and retaining the heat, depending upon these factors the duration and period is chalk out.
The effect of heat can be superficial or deep,wax bath , infrared,hydrocollateral pack etc.supply heat superficially only., where as shock wave dithermy , ultrasound etc used frequently in physiotherapy clinics provide deep heat.Superficial heat is applied in case of chronic effect of injury, which application helps to reduce muscle spasm by reducing tone and again muscle relaxation thereby improving the joint function. It brings vosodilatation also .In acute injury heat application is containdicated in Ayurveda.
Shock wave dithermy radiates heat used; the body need not be touched by instrument but can cause radiation hazards in the long run and hence no longer used in the advanced countries; ultrasound heat the Inside of the Articular spaces, ligament; is safe and can be used to joint immobility in cases of stiffi,contractures etc.
As a rule, superficial heat can be employed in diseases of Bahya rog marg( external pathway of diseases) and deep heat is indicated in diseases of Madhyam rog Marg( middle pathways of diseases).In diseases of Abhyantar( internal) rogmarg , sudation is not necessary,as the diseases is in GIT tract intract itself and the doshas can be mobilised and channelized by as simple procedures as drinking water.It is also to be emphasized that the methods of heat transfer usually use of Ayurvedic therapies like pottalis,parishek etc impart deep heat by virtue of not only the medicated oils which we use helps deliver the exact medicine ,targated to the exact side needed- this being unique to Ayurveda.Deep heat is to be applied most of the conditions as most of them are madhyam Rog marg , afflicting joint and nerves.
The heat retention ability of materials are also to be taken into consideration.Svedan can be objectively assessed by at least the following seven parameters:
Effective stress index,predicted sweat loss, psychological strain index, Modified discomfort index, Environmental stress index
,,Skin wettend- ness and of course for those who are involved in boxing and gymnastics,Fighter index of thermal stress.The entire wastes to be eliminated may be divided into two : water soluble and fat soluble.By doing sudation,water soluble wastes of the body ( especially in Amavastha / accumulation of toxins on cellular level) are dissolved in water ( extra cellular body fluids) propelled by the heat and brought to the nearest port of the elimination. In the process of elimination of water soluble wastes,the role of unction is less appreciated.On the contrary unction may be determined as it may prevent dissolution of water soluble wastes. On the other hand in the case of fat soluble wastes,sneha ( oil based medicine) dissolved in fat medium,these are propelled by by sweda t the nearest port of elimination. Dissolution of wastes and toxins in fat is slower,hence it is not a once - far- all programme and had to be repeated daily till the desired effect is achieved.
The primary requirements of SWEDAN is to reduce the pain and stiffness ad per ongoing study with regards to pain pathways, neurotransmitters like substance-p,and Glutamate ,analgesia pathway, control theory and it's subsequent applications in release of endogenous pain relievers etc. Are to be revisited in the backdrop of massage with sneha- sweda.The efficiency of human skin as the most sensetive' touch screen ' working by 'touch flow soft wares' is a million times more sophisticated than the present day ' resitive' and ' capacitive' touch screens touch screens or 'Displax skin' screens involving the most advanced nano - wire technology on polymer films.
Temperature is a form of energy, which brings about a change in the internal environment,a stimulus; it indicates excitability by its intensity and duration. The receptor a for warmth at the skin are Raffine's end bulb and for cold Krause's end bulb.These are tonic receptores which adopt only slowly .The sensation after transduction passes through posterior nerve root ganglion and substantia gelatinosa consisting of fibers from lateral spino thalamic tract of spinal cord,then passes through ventral, posterior,lateral nucleus of the thalamus to end in the somesthetic cortex It is further to be noted that through the receptors for kinasthetic cortex.It is further to be noted that though the resceptersfor kinasthetic sensations - both conscious and subconscious,are also resceptors for pressure,crude touch, vibration and even pain involved in the firm massage
,Are distinct and separate ( Refference:
Muller's law of specificity of response)
The first order neurone,third order neuron and the broad area of the cerebral interpretation are essentially same for all these sensations,thus it can be seen that the traiad of external unction, massage and increased temperature; the hallmarks of Sarvangadhara act by stimulation of varying centers of sensory cortex. The thermal range of nerve fibres activity 0-50 degree Celsius and would be inactive below 0 degree Celsius,but this happens only on ditect stimulation of nerve .When external unction using warm oil is applied,the upper temperature range differs slightly as it has to pass through skin .the patient tolerates upto 52 degree Celsius of heat of oil used- depending upon the room temperature and the individual. The normal heat coefficient of nervous impuls is that, with every 10 degree Celsius rise of temperature,the velocity of the impulse is doubled.
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