STRUCTURAL ORGANISATION OF THE NERVOUS SYSTEM
The central nervous system (CNS) is the computer that manages all the nervous information. This fonction is done by the brain. For its communication the CNS needs nerves. There are two big types of nerves :
- Afferent or sensory, they carry sensitive information from the periphery to the CNS (ex : the feeling of the centre of the heel touching the ground)
Efferent or motor, they carry motor information from the CNS to the periphery (ex. the message is sent for the arm or leg to bend)
The efferent nerves are divided in to groups :
- The somatic nervous system is responsible for the volunteer action (ex : I press the centre of the heel down)
- The autonomic nervous system (ANS) gives the information to the organs, and help them to maintain homeostasis. Homeostasis can be defined as a property of an organism or system that helps it maintain its parameters within a normal range of values. (ex : regulate te heart beats)
AUTONOMIC NERVOUS SYSTEM (ANS)
The ANS has two arms, parasympathetic and sympathetic. The parasympathetic division promotes maintenance functions and conserves body energy. The sympathetic division mobilizes the body during activity. Both divisions generally serve the same visceral organs but cause opposite effects : while one division stimulates certain smooth muscle to contract or a gland to secret, the other division inhinibs that action. Through this dual innervation the two divisions counterbalance each other to keep body systems running smoothly. The two divisons don’t work at the same time.
It is the « rest and digest » system and keeps the body’s energy use as low as possible. It is performing the « housekeeping » activities as digesting food, eliminating feces and urine. This explains why it’s good idea to relax after heavy meal : so that sympathetic activity does not interfere with digestion.
Exemple of action : low heart beats, activate the gastro-intestinal tract, constriction of the pupils.
YOGA UNDERSTANDING :
The location of the parasympathetic system is mainly in two parts :
Sacrum : with a connection to small intestine, rectum, urinary system, uterus and ovaries, sexual organs.
Cranial, base of the skull : with a connection to eyes, heart, lung, liver, stomach, pancreas, large and small intestine, etc.
Any posture working on this two areas will also send information to the organs associated.
The particular asana which stimulates the sympatetic nervous system is Sarvangasana (Shoulder Stand).
It is the « fight or flight » system. Its activity is evident when we are excited or find ourselves in emergency, or fearfull situation, etc.
Example of action : rapid heart beats, fast breathing, dry mouth, cold sweaty skin, constrict blood vessels to activate the skeletal muscles, dilated lung, etc.
YOGA UNDERSTANDING :
The location of the sympathetic system take place in sympathetic ganglion just next to the thoracic and lombar vertebras.
Any kind of posture working on this area will also send information to the organs associated.
The particular asana which stimulates the parasympatetic nervous system is Hanging Sirsasana.
Himalayan Iyengar Yoga Centre