by Baxter and Nina
Although we tend to think about the nervous system only when we�re feeling stressed (or nervous!), your nervous system is essential for your survival. Basically, it provides the following essential functions:
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| Nerve Cells |
- Controls background processes that keep your body alive and healthy, such breathing, maintaining normal temperature, and adjusting blood pressure to match activity.
- Responds to external stimuli (which come in through our senses), such as having a positive reaction to a beautiful smell, a pain response to a burn, or a quick reaction to an oncoming car
- Obeys our conscious mental instructions, such as to talk, move, or breathe more slowly.
By communicating through your nerves, your nervous system constantly monitors the internal activities of your body systems, attempting to keep them in a healthy balance called �homeostasis.� It also monitors your environment to assess if it is safe or dangerous, and sends messages to your body either to relax and enjoy or act quickly to get to safety.
Your nervous system is made up of two main parts: the central nervous system and peripheral nervous system. However, even though we�and our anatomy books!�always discuss the central nervous system and peripheral nervous system as two separate systems (see below), they are really a continuation of one another and are in constant communication with each other about the state of your body.
Chronic stress has a negative effect on your nervous system, contributing to the development of anxiety, depression, sleep problems, lack of concentration, and memory impairment. Therefore, using your yoga practice to keep stress levels in check and to manage your stress during challenging periods, will support the health of your nervous system overall. Additionally, besides by staying generally healthy through exercising regularly, eating a healthy diet and drinking enough water, getting enough rest, and avoiding smoking, you can support the health of your nervous system by:
- Treating conditions that can negatively impact the system, such as diabetes and hypertension.
- Avoiding alcohol and drugs that affect the nervous system.
- Decreasing use of over-the-counter medications, because as you get older, these can negatively affect your nervous system.
- Testing your hearing and vision regularly (when they are not working well the brain has a harder time recording information).
- Cultivating brain health (see 6 Ways to Foster Brain Health with Yoga).
Neurons. The basic component of your nervous system is a specialized cell called a neuron, which are both part of your brain and also make up your nerves. The human brain contains about 86 billion neurons, and its neurons are densely packed and are only 10 microns long. While aging results in the loss of some of our brain neurons, the ability of our brains to grow and change (brain plasticity) means that continuing to stimulate our brains with learning will actually cause our brain neurons to grow and existing brain neurons to be repurposed.
Neurons connect the brain proper to your spinal cord, and from the spinal cord connect to neurons in your peripheral nerves. Using your asana practice to maintain healthy posture and proper alignment of your spinal bones will help to keep your spinal cord safe from pinching and narrowing, which could cause nerve dysfunction or pain.
Your peripheral nerves consist of longer neurons, which can be up to 1 meter in length. They transmit messages through the nerve via electrical signals and use chemical neurotransmitters to send the impulses from one neuron to the next. A sedentary lifestyle and structural injuries can negatively impact your peripheral nerves. With a regular asana practice, you can release holding patterns around your nerves, allowing them to function them better.
Central Nervous System. Made up of your spinal cord and your brain, your central nervous system receives and processes information from all over your body. In response to conscious thoughts, your central nervous system sends nerve impulses to your peripheral nervous system to make the requested action happen. And in response to nerve impulses that your central nervous system receives from your senses and your autonomic nervous system (which keep your background systems in balance), your central nervous system sends nerve impulses to make your body react appropriately.
Besides communicating through your nerves, your central nervous system also communicates with your organs and the rest of your body through chemical and hormonal messages, for example, by releasing the stress hormone adrenaline when you need to react quickly.
Peripheral Nervous System. Consists of nerve fibers that branch off from your spinal cord and extend to all parts of your body, including your neck, arms, torso, and legs, as well as all your muscles and internal organs. The nerve receptors and long nerves that travel all over your body and back to your central nervous system are either delivering information to your central nervous system or receiving instructions from it. For example, when you decide to raise your arms in Warrior 1 pose, your brain sends a message via the peripheral nervous system to the appropriate muscles. Or, when you�re stressed, your peripheral nervous system speeds up your heart rate. Likewise, if you cut yourself, taste some chocolate, or sniff a flower, your peripheral nervous system communicates lets your brain know all about it.
The peripheral nervous system is divided into somatic and autonomic systems.
Somatic Nervous System. Provides voluntary control of your body movements. In yoga, we use our somatic nervous system when we practice poses, perform breath practices, stay still when we meditate, and consciously relax muscles in restorative poses and guided relaxation. Obviously we want our somatic nervous to function optimally because to function well in our daily lives we need quick and coordinated responses to our mental requests for movement or rest. You can use your asana practice to support the health of your somatic nervous system by practicing a wide variety of poses and movement patterns to activate all those nerves on a regular basis, and by practicing balance and flow poses to keep your proprioceptors (the nerves that allow you to sense where you are in space) healthy.
Autonomic Nervous System. Regulates involuntary body functions, such as heartbeat, blood flow, breathing, and digestion. It�s called �autonomic� because it works autonomously (automatically) without your conscious effort. (You don�t need to tell your heart to beat the same way you need to tell your front knee to bend to 90 degrees in Warrior 2 pose. Voluntary movements, such as knee bending, are controlled by your somatic nervous system.)
Although the functions of the autonomic nervous system are generally involuntary, some of them are not outside of your awareness, and they may be influenced by your state of mind. For example, although you can�t tell your heart to beat faster or more slowly, you can feel it beating. And when you�re calm, you�ll notice that your heart beats more slowly and when you�re afraid or angry, you�ll notice it beating more rapidly.
The autonomic nervous system is divided into two parts that function in tandem with each other: the sympathetic nervous system and the parasympathetic nervous system. Learning about these two systems and how they interact with each other is one of the secrets to learning to keep your stress levels in check (see Life Changer: Understanding Your Nervous System).
We hope this little anatomy lesson helps you understand the importance of your nervous system and the value of giving it active attention as you age. All the yoga tools at your disposal, including asanas, meditation, breath practices, relaxation practices, and even yoga philosophy, will help you support its good health.
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