Kriyā Sharīra (Physiology in Ayurveda) — A Complete Overview

Kriyā Sharīra (Physiology in Ayurveda) — A Complete Overview

Kriyā Sharīra is the branch of Ayurveda that deals with the functions, mechanisms, and physiological processes of the human body. While Rachana Sharīra explains how the body is built, Kriyā Sharīra explains how the body works. This includes the study of Doṣa, Dhātu, Mala, Agni, Srotas, Ojas, Prāṇa, and all dynamic functions essential for life. Ayurveda considers physiology as a continuous interplay of physical, mental, and spiritual factors, making Kriyā Sharīra a deeply holistic science.

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1. Central Concepts of Kriyā Sharīra

A. Tridoṣa – The Regulatory Principles

Ayurvedic physiology is founded on the Tridoṣa Siddhānta:

• Vāta Doṣa – governs movement, nerve impulses, circulation, respiration

• Pitta Doṣa – governs metabolism, digestion, transformation

• Kapha Doṣa – governs stability, lubrication, immunity

These doṣas are not physical substances but functional forces. Their balance maintains health; imbalance leads to disease.

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2. Agni – The Digestive & Metabolic Fire

Agni is considered the foundation of life.
Ayurveda describes 13 types of Agni:

• Jatharagni – main digestive fire

• Dhātuvagni – 7 tissue-level metabolic fires

• Bhūtāgni – five elemental metabolic fires

Proper Agni ensures:

• Good digestion

• Healthy absorption

• Balanced metabolism

• Strong immunity

• Mental clarity

Impairment of Agni (Agnimāndya) is the root cause of most diseases.

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3. Dhātu – Body Tissues

Seven Dhātus form the structural and functional units of the body:

1. Rasa – plasma, nutrition

2. Rakta – blood, oxygenation

3. Māmsa – muscle tissue

4. Meda – fat

5. Asthi – bone

6. Majjā – marrow & nervous tissue

7. Śukra / Artava – reproductive tissues

Each Dhātu is nourished sequentially.
Disorders occur when dhātu formation or transformation becomes abnormal.

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4. Mala – Waste Products

Mala are essential by-products of physiology:

• Purīṣa (stool)

• Mutra (urine)

• Sveda (sweat)

Proper elimination maintains internal balance. Retention or excess excretion creates disease.

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5. Srotas – Channels of Circulation

Srotas are micro- and macro-channels that conduct materials throughout the body:

• Prāṇavaha (respiratory)

• Rasavaha (circulatory)

• Ārtavavaha (female reproductive)

• Anna-vaha (gastrointestinal), etc.

Blockage (srotorodha) or weakness (srotodushti) disturbs physiology and leads to disease.

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6. Ojas – Vital Essence & Immunity

Ojas is the end product of perfect digestion, dhātu formation, and mental stability.
It represents:

• Immunity

• Strength

• Stability of mind

• Longevity

Loss of Ojas leads to fear, weakness, disease, and even death.

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7. Prāṇa – Life Force

Prāṇa governs:

• Respiration

• Heartbeat

• Consciousness

• Sense functions

• Vitality

Prāṇa is closely connected with Vāta doṣa and Ojas.

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8. Manas – Mind in Physiology

Ayurveda includes the mind as part of physiological processes.
Manas controls:

• Thought

• Memory

• Emotions

• Sensory interpretation

• Stress responses

Mental disturbances affect digestion, sleep, hormones, immunity, and reproductive health.
Thus, mental and physical health are inseparable.

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9. Functions (Kriyā) of Major Systems

Digestive System (Annavaha Kriya)

• Food digestion begins with Agni

• Absorption through srotas

• Transformation into dhātus

Circulatory System (Rasavaha Kriya)

• Rasa and Rakta nourish tissues

• Controlled by Vyana Vāta and Ranjaka Pitta

Respiratory System (Prāṇavaha Kriya)

• Governed by Prāṇa Vāta

• Breath fuels metabolic fires

Nervous System (Majjāvaha Kriya)

• Vāta regulates impulses, reflexes, and cognition

Endocrine & Metabolic (Dhātwagni Kriya)

• Hormonal/metabolic balance equated with Agni functionality

Reproductive System (Śukra/Artava Kriya)

• Depends on Ojas, proper dhātu nutrition, and Vāta

Ayurveda emphasizes functional unity, not isolated systems.

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Summary — What Kriyā Sharīra Teaches

Kriyā Sharīra explains:

• How the body functions

• How doṣas regulate life

• How digestion and metabolism shape health

• How tissues are nourished

• How waste products maintain balance

• How channels allow movement

• How immunity and vitality arise

• How mind and body work as one

It provides the physiological basis for diagnosis, treatment, and preventive medicine in Ayurveda.