“Principles of Physiology in Ayurveda (Part -1- Basics)”
This is a transcript prepared by Dr. Varsha More,
based on the lecture available at Ayurvedic Principles of Human Physiology
शरीरविचयःशरीरोपकारार्थमिष्यते|ज्ञात्वा हि शरीरतत्त्वं शरीरोपकारकरेषु भावेषु ज्ञानमुत्पद्यते| तस्माच्छरीरविचयं प्रशंसन्ति कुशलाः|| (Ch.Sha 6/3).
In Ayurveda, physiology and anatomy have been not separately explained. In Charak Samhita, the term Sharir Vichay has been mentioned. Sharir Vichay is the branch of science that has been explained for the purpose of the wellbeing of the human being. One will be able to understand the factors that are helpful for the maintenance of health only by understanding the term Sharir. Sharir vichay means analytical knowledge of the human body. Therefore this branch of science which is called Sharir Vichay has been well acclaimed by the experts. Therefore it occupies an important place as long as the understanding of interventions and the lifestyles measures that are intended at the maintenance of health are concerned.
Concept of homeostasis:
Homeostasis is the state of equilibrium or normalcy when all the mechanisms are operating at their optimal level. Currently, the term homeostasis is being often replaced by the term ‘Homeodynamics’, as the equilibrium in human beings is not maintained at a static phase rather it is maintained at a dynamic state, which in turn is maintained by multiple dynamic factors. Homeostasis means the state of equilibrium /normalcy when all the mechanisms operate at their optimal level.
विकारो धातुवैषम्यं, साम्यं प्रकृतिरुच्यते|(Ch. Su.9/3)
Charaka quotes that the equilibrium in the status of Dhatu is called Prakriti (normalcy) while the disequilibrium state is called Vikara. (ch. Su.9/3). Here the term Dhatu is used to indicate all factors that are involved in the maintenance of human health. Dhatu means ‘धारणात धातवः’ the one helps in the sustenance of the human body at its optimal status. Dhatus are often translated as tissues, but all the Dhatu don’t meet the definition required for the term ‘Tissue’ as per the modern biomedicine perspective.
प्रकृतिभूतानां तु खलु वातादीनां फलमारोग्यम्|(Ch.Sha. 6/18).
Acharya Charak quotes that when Vatadi Doshas are in the state of normalcy results in the state of health or well-being. The terms like Dosha, Dhatus are sometimes interchangeably used in Samhitas at various places. Here the Doshas can be considered as Dhatus when they are in the equilibrium state.
धातुसाम्यक्रिया चोक्ता तन्त्रस्यास्य प्रयोजनम्||(Ch. Su.1/53).
According to Charak, all the efforts that are aimed at establishing the Dhatusamyata i.e equilibrium is the major objective of the entire science of Ayurveda. All of the above references are pointing towards the concept of homeostasis as perceived in Ayurvedic textbooks.
Concept of cell:
As the textbooks of Ayurveda were written about 2000 years ago, explanations based on the microscopic appearance of tissue or cells would not be available. But certain explanations hint at the conceptual level of understanding of the human body, especially the living units of the human body. In Ayurveda, certain terms have been used to indicate the minute living unit that makes up the entire body.
शरीरावयवास्तु परमाणुभेदेनापरिसङ्ख्येया भवन्ति, अतिबहुत्वादतिसौक्ष्म्यादतीन्द्रियत्वाच्च| (Ch.Sha. 7/17)
As mentioned by Charak, the body parts if further divided at the micro-level (Parmanu) are innumerable because of abundance (Atibahuta), highly subtleness (Atisukshma), and imperceptibility (Atindriya). (Ch. Sha. 7/17).
अपि चैके स्रोतसामेव समुदयं पुरुषमिच्छन्ति, सर्वगतत्वात् सर्वसरत्वाच्च दोषप्रकोपणप्रशमनानाम् Ch. Vi 5/4).
Charak quotes some scholars where it has been proposed that the entire human body is nothing but an aggregation of Srotamsi only. All the factors which aggravate or suppress the Dosha can move and spread all over the body through Srotas. Hence Srotamsi are fundamental units of the body. (Ch. Vi 5/4). Thus the structural and functional importance of minute structures like Sharir Parmanu and Srotas has been explained in the Ayurveda texts.
स्रोतांसि खलु परिणाममापद्यमानानां धातूनामभिवाहीनि भवन्त्ययनार्थेन|| (Ch. Vi 5/3).
Srotamsi are nothing but the channels or pathways carrying Dhatus which are undergoing the process of transformation. Therefore all those pathways where some kind of transformation takes place can be termed as Srotamsi.
स्वधातुसमवर्णानि वृत्तस्थूलान्यणूनि च| स्रोतांसि दीर्घाण्याकृत्या प्रतानसदृशानि च||(Ch.vi.5/25).
Each dhatu has its corresponding Srotas. The appearance of Srotas is similar to its corresponding Dhatu. Some of them could be circular (Vritta), gross or microscopic (Sthula or Anu), elongated, and reticulate (Pratan) appearance. (Ch.vi.5/25).These are possible structures in the body, especially the structures that are equivalent to tissues in the body.
This entire explanation is indicative of the two inferences. First inference suggests that individual Dhatu is structurally related to its corresponding Srotas while the second inference suggests that individual Dhatu is functionally related to its individual Srotas.
The word ‘परिणाममापद्यमानानां’’ means undergoing the process of transformation. This represents the metabolic relationship between individual Dhatu and corresponding Srotas.In summary, Dhatus are structurally and metabolically related with their corresponding Srotas. In terms of modern biomedicine, tissues are nothing but an aggregation of structurally and functionally similar cells. So this concept can be identified in these two references (Ch. Vi 5/3, Ch.Vi.5/25)from the Charak Samhita.\
In Ayurveda understanding of tissue is not based upon histological observations. The perspective of Ayurveda to understand the human body is different than that of modern biomedicine. Each tissue was identified and described from different perspective.
रसाद्रक्तं ततो मांसं मांसान्मेदस्ततोऽस्थि च| अस्थ्नो मज्जा ततः शुक्रं शुक्राद्गर्भः प्रसादजः||(Ch. Chi 15/16)
There are seven Dhatus that have been described. In Ayurveda, the fundamental structural entities described are Dhatus and Updhatues. The dhatus are Ras, Rakta, Mamsa, Meda, Asthi, Majja, and finally the Shukra from which Garbha is formed. (Ch. Chi 15/16)
रसात् स्तन्यं ततो रक्तमसृजः कण्डराः सिराः| मांसाद्वसा त्वचः षट् च मेदसः स्नायुसम्भवः| (Ch. Chi 15/17)
Updhatus are derived after their primary dhatus. Stanya (breast milk) and the Asruja (menstrual blood) are derived after Rasa. Asruja has a different meaning according to context, sometimes it means ovum and sometimes it means menstrual blood. Kandara (tendon) and Sira(vein) are derived after Rakta. Vasa (muscle fat) and the six layers of Tvacha (skin) are derived after Mamsa (muscle) and Snayu(ligament) are derived after Medas (adipose tissue)(Ch.chi15/17).
Primary understanding related to the concept of Dhatus:
Ras: It fundamentally indicates all the flowing colourless fluids containing nutrient material that may include plasma, interstitial fluid.
Rakta: It mainly stands for a red color fraction in the human body which is responsible for oxygenation.
Mamsa: It is equivalent to the flesh while the term Mamsa Peshi is equivalent to muscle.
Meda: It stands for the adipose tissue along with circulating lipids. As there are two types of Meda namely Baddha and Abaddha Meda. Baddha meda indicates stored fat while Abaddha meda indicates circulating lipids.
Asthi: It mainly stands for bones along with all the hard structures that resist easy decomposition. As per Ayurveda, hard structures like nails and teeth are considered under the category of Asthi.
Majja: It stands for the substance that fills the bony cavity. This bony cavity may be present within a single bone e.g. the presence of bone marrow inside the bone. This bony cavity may be formed by the union of several bones eg. the cranial cavity that is filled by brain tissue. Therefore brain substance present within the skull can be considered as Majja. Majja is not equivalent to bone marrow, all bone marrow is Majja but all Majja is not bone marrow.
Shukra: There are two types of Shukra, one circulates in the body. This Shukra that is derived from Majja, possibly represents hypothalmo pituitary-gonadal axis that is circulating all over the body. The other one Shukra possibly includes male reproductive factors, semen, and sometimes sperm. Sometimes female reproductive tissues can be included under this category.