“The nervous system is a complex collection of nerves and specialised cells known as neurons that transmit signals between different parts of the body. It is essentially the body’s electrical wiring”

Nervous system

Nervous system

• Central !

• Peripheral !

• Somatic !

• Autonomic: Sympathetic !

Parasympathetic

• Central - Brain, spinal cord and retina

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• Peripheral - sensory neurons, ganglia and nerves that connect the extremities to the CN

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• somatic - is the part of the peripheral nervous system associated with skeletal muscle voluntary control of body movements

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• Autonomic - regulates the functions of our internal organs (the viscera) such as the heart, stomach and intestines

The autonomic nervous system controls internal body processes such as the following:!

!• Blood pressure

!• Heart and breathing rates

!• Body temperature

!• Digestion

!• Metabolism (thus affecting body weight)

!• The balance of water and electrolytes (such as sodium and calcium)

!• The production of body fluids (saliva, sweat, and tears)

!• Urination

Autonomic two main divisions

• Sympathetic !

Flight, fight, freeze !Prepares the body for stressful or emergency situations !

• Parasympathetic !

Rest and digest (savasana) !Controls body process during ordinary situations

Many organs are controlled primarily by either the sympathetic or the parasympathetic division

The two divisions have opposite effects on the same organ

For example, the sympathetic division increases blood pressure, and the parasympathetic division decreases it

The two divisions work together to ensure that the body responds appropriately to different situations

Signs of stress!

• blood pressure (pressure in your blood vessels is needed to circulate the blood)

• Heart rate (number of times a person's heart beats per minute)

• Pupils dilate for better vision

• Immune system shuts down

• Digestion shuts down

• Muscle tone

• Clammy hands and feet

• Excess sweating

• Mental stress

• Dry mouth

How yoga breathing and relaxation can affect the autonomic nervous system

• The SNS, in conjunction with such stress hormones as adrenaline and cortisol, initiate a series of changes in the body, including raising blood pressure, heart rate, and blood sugar levels. These changes help a person deal with a crisis situation. They mean more energy and more blood and oxygen flowing to the large muscles of the trunk, arms, and legs, allowing the person to run from danger or do battle (the so-called “fight-or-flight” response).

• The PNS, in contrast, tends to slow the heart and lower the blood pressure, allowing recovery after a stressful event. Blood flow that was diverted away from the intestines and reproductive organs, whose function isn’t essential in an emergency, returns. In contrast to fight or flight, these more restorative functions can be thought of as “rest and digest.” They are also sometimes dubbed the relaxation response.

• Many yoga practices, including quiet asana, slow breathing, meditation, and guided imagery, increase activation of the PNS and lead to mental relaxation.

• Yoga techniques are more than just relaxation, however. Practices like vigorous sun salutations, kaphalabhati breathing, and breath retentions actually activate the SNS. One of yoga’s secrets, documented in research from the Swami Vivekananda Yoga Research Foundation near Bangalore, is that more active practices followed by relaxing ones lead to deeper relaxation than relaxing practices alone. - YOGA JOURNAL

High blood pressure‘High blood pressure (hypertension) rarely has noticeable symptoms, but if untreated it increases your risk of heart attack, heart failure, kidney disease, stroke or dementia’ NHS

‘Your heart pumps blood around your body to deliver energy and oxygen. A certain amount of pressure in your blood vessels is needed to do this. However, if there is too much pressure in your blood vessels, it puts extra strain on your arteries and heart, which can lead to serious conditions such as heart attack, heart failure, kidney disease, stroke, or dementia’ - NHS

Medication is used to treat this condition

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• Inversions affect blood pressure

• In an inverted posture, gravity causes pressure to increase inside the blood vessels (arteries, veins, and capillaries) of the head and neck.

• How far above the head is the heart?

• Mildly inverted posture like Adho Mukha Svanasana (Downward-Facing Dog), which lifts the heart only a little above the head and does not elevate the legs, only increases pressure in the head a little.

• Salamba Sarvangasana (Shoulderstand) increases pressure in the head still more, because the legs and trunk are raised to their maximum vertical position above the heart.

• Sirsasana (Headstand) increases blood pressure in the head the most, because the legs and trunk are maximally elevated and the head is as far below

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