Introduction

There are various pathways within the human body which communicates and links the different corners. These pathways help in manufacture and transportation of essential ingredients and support the life entity, the basic amenities needed to manufacture and create the tissues of the body and to flush out the unnecessary things out of the body. The healthy existence and proper functioning of these pathways defines our existence, health and immunity status. The pathways, when get blocked, chocked, or contaminated leads to serious damages, diseases and also death. Millions of ducts, tubes and channels are present in body which make what we are, which keeps us connected to the interior and exterior worlds, which connects us to selves, which binds the body, mind, senses and soul under one roof, which makes and breaks us, which phenomenally carry out all the life activities and functions effortlessly and selflessly, they are called ‘Srotas’.1

Srotas are also called as ‘Kha’ derived from Sanskrit word Akasa which indicate empty space. These are the channels in the form of tracts, veins, arteries etc. They carry and transport four types of food, Dhatus, Doshas and Malas.2 Dhatu sustains the body and nourishes the successive Dhatu only when digested full by its Agni and transported properly through its channel.Thus Srotas play important role in Dhatupaka (metabolism).

Etymology:

The word ‘Srotas’ is derived from ‘Sru’ which means oozing. The oozing of nourishing fluid and the return of waste matters take place through these Srotas.3

Historical aspects

According to the Mahaprajanaparamitasastra of Mahayana branch of Buddhism, Srotas refers to the “stream” (noble eightfold Path) and through these streams one can enter into the stream of Nirvana.

In Jain text Tattvarthasutra, Srotas word is mentioned to be derived from Srotendriya which refers to one of the “five sense-organs”.

The different names or synonyms of all the visible and invisible srotases available in the body are Sira, Dhamani, Rasaayana, Rasa vaahini, Naadi, Shareera chidraani, Samvruta-asamvruta Sthaana, Aashaya, etc.

Types of Srotas

According to Acharya Charaka, Srotas are Aparisankhyeya in the body and he has classified Srotas into 13 types whereas Acharya Sushruta has classified 11 pairs of Srotas. Srotas can be classified on different basis:5

• In Sharir sthana and Ashtang Hridaya, Srotamsi are classified on the basis of number

1.  Suksma (innumerable)

2.  Sthula (numerable). 

• On the basis of perceptibility

1. Drushya (perceptible)

2. Adrushya (imperceptible)

• On the basis of Adhishthana

1. Sharirika

2. Manasika

• On the basis of Sthanabheda

1. Bahirmukha (outside opening)- 9 in male, 11 in female

• 2 Akshi (eyes)
• 2 Nasika (nose)
• 2 Karna (ears)
• 1 Mukha (oral cavity)
•  1 Guda randhra,
•  1 Vedana randhra.

 (In females - 2 Stana randhra and 1 Rakthapatha)

1. Antarmukha (inside opening)- 13

According to Charaka, there are 13 main Antarmukha Srotas.

They are:
Pranavaha Srotas – Channels carrying the vital life element or air
Annavaha Srotas – Channels transporting food
Udakavaha Srotas – Channels carrying water and controlling water metabolism
Rasavaha srotas – Channels carrying the nutritional essence
Raktavaha Srotas – Channels carrying the blood
Mamsavaha srotas – Channels carrying muscle tissue
Medovaha Srotas – Channels carrying fat tissue
Asthivaha Srotas – Channels transporting the bone tissue
Majjavaha Srotas – Channels carrying the bone marrow tissue
Shukravaha Srotas – Channels carrying the semen or reproductive tissue
Mutravaha srotas – Channels carrying urine out of the body
Purishavaha Srotas – Channels carrying stools out of the body
Swedavaha Srotas – Channels carrying the sweat

Detailed view of Srotas

Ayurveda believes that everything in this universe is made up of five basic elements termed as Panchmahabhuta. Akasha is considered as the basic Mahabhuta responsible for the presence of spaces in the body such as inter and intramolecular space; various channels, etc. Srotas are considered to be formed by Akasha mahabhuta, because they show characteristics such as porous, clean, softness, thin, colourlessness and transparent.6  Srotas can be found all the way from the root to the tip of any building or body. Srotas are found within the body's gaps; they spread throughout the body and transport vital elements. Siras (veins, lymphatics, etc.) and Dhamani structures are completely separate from Srotas. Srotas possess the hue of the Dhatu (tissue) that they are carrying or transporting. They have variety of forms and sizes, including round, thick, huge, tiny, microscopic, and elongated, and they create a network and branches. Because the transportation process happens both within the cell and between cells, each cell may be called a Srotas according to this definition. Acharya Sushruta has described Srotas as continuous channel (blood vessels) which forms a closed tubular system, originating from a vacant space, spreads throughout the body, carries materials Rasa, Rakta etc. Sushruta has excluded Sira and Dhamani from the Srotas and compared the Srotas to the fine channels present in the lotus stem through which fluids circulate. Dalhana has accepted that all structures through which Prana, Anna, Rakta circulate as Srotas.

Srotas Mula Sthana:

According to Acharya Charak the term Mula implies Aadhar (base). In Sushruta Samhita Mula word is used to represent. The commentator of Charaka Samhita, Chakrapanidatta has quoted “Mulamiti Prabhava Sthanam” which means that Mula is the Prabhav sthana of the Srota. It is the anatomical seat of the respective Srotas, the main seat of the Dushti (pathology) of that Srota, the principal seat of manifestation of disease. Srota mulasthana is the area from which Srotas evolves or arises. He has compared Mulasthana with the root of the tree. Roots are the originating point; they nourish the tree and provide it support. If the root is destroyed, it will cause harm to the whole tree; in the same manner, if harm is caused to Srotomula, it will cause damage to whole Srotas.7

Discussion

Acharya Chakrapani mention about Sravarnat as Sravanam of Rasadi Poshya Dhatu. According to him, Srotas are the channels or systems where some tissue is formed; some material is metabolized, secreted or transported. Acharya Dalhana stated that all visible and invisible structures, possessing qualities of Akash mahabhoota are Srotas. They transport the Dhatus, Upadhatus, Anna, Jala, Prana Malas, etc. from one place to another in the body. Thirteen main channels are described, seven for seven dhatu, three for mala and two for intake of nutrient substances like food, water, air and one for regulation of water. Mula as Prabhav sthana means the anatomical seat of respective Srotas, main seat of pathology of that Srotas or principal seat of manifestation of the diseases of that Srotas.10 The cause of morbidity of Srotas and their manifestations first strikes the Mulasthana of the respective Srotas. This morbidity slowly spreads throughout the body.

Conclusion

Srotas means the structures through which circulation of Poshaka dhatu (nutrients) takes place in body. Srotas are continuous channel which forms a closed tubular system, originating from a vacant space (mulat khadhantaram) and transport materials like Prana (Life element), Anna (Food), Vari (Water), Mamsa, Meda Dhathu, etc. The living body is the result of aggregation of innumerable ‘Srotamsi’, that are transporters of factors which causes Prakopa (excitation) or Shamana (allevation) of Sharira doshas. Srotas are concerned with the metabolic state of their corresponding tissues through different communicating mechanisms.