A Guide to Your Nervous System & 6 Tips for Regulation
Your nervous system is at the heart of your experience and survival on Earth. It controls your voluntary and involuntary actions, allowing you to move through the external world, whilst maintaining communication in your internal world, within your body.
When balanced (aka regulated), your nervous system switches between its different modes to provide you with the tools you need. If it’s out of balance (or disregulated), we can experience chronic stress, anxiety, physical health problems and more. The balance we’re looking at here is that between the parasympathetic (‘rest-and-relax’) and the sympathetic (‘fight-or-flight’) nervous systems, but it’s a lot more complex than that.
This Guide will give you all of the practical, down-to-earth information you need to know to better understand your nervous system, appreciate its complexity and, in turn, support its regulation and health.
The nervous system can be divided into the central nervous system (CNS), comprising the brain and spinal cord, and the peripheral nervous system (PNS), comprising nerves that carry information to and from the central nervous system to/ from the rest of the body. There are two types of cells in the nervous system - neurons, which are electromagnetic conductors, carrying messages and instructions, and glial cells, which support the neurons. It’s the neurons that are key to communication in the nervous system.
Communication in the nervous system
Neurons are made up of a cell body, which contains the nucleus, and out of which a number of dendrites extend out to meet with other neurons. Where they do, they form synapses, across which messages are received from other cells. Out of the cell body of the neuron also extends a long, slender projection called an axon, along which messages are sent out. So, neurons receive messages via their dendrites and send messages via axons, and the communication occurs at synapses.
Dendrites are around 1.5mm, whereas axons vary from 1mm to 1m in length! The longest axons in the body are those of the sciatic nerve, which runs from the base of the spinal cord to the big toe of each foot. (Note: Some neurons don’t have axons or dendrites, but most do.)
What we know as a nerve is a bundle of axons in the peripheral nervous system (PNS). In the central nervous system, this bundle of axons is called a tract.
But what do we actually mean by ‘messages get sent and received’? Neurons communicate through electrical and chemical signals. A neuron sends an electrical signal, which is translated into a chemical signal at the synapse to cross the gap to the other neuron, where it become electrical again. The chemical signals occur through what are called neurotransmitters, which are created by neurons and released into the synapse when a cell becomes activated. The electrical charge is caused by positive sodium atoms rushing into the neuron, and negative potassium atoms rushing out. When this electrical impulse arrives at the nerve ending, it triggers the neuron to release the neurotransmitter to complete the message sending out. So, it’s the electrical and chemical signals working together that allow communication in the system.
The central nervous system (CNS)
The brain is the commanding centre of the body, connected to the spinal cord at the brain stem, which is located at the lower part of the brain. The spinal cord carries messages between the brain and the nerves that run throughout the body (i.e. between the CNS and the PNS).
The brain contains 100 billion neurons and is divided into 4 parts:
Cerebrum (largest part of the brain, comprising 85% of total brain weight)
Made up of 2 hemispheres, which are in constant communication with each other; the right is more intuitive, creative, language; the left is more logical, analytical rational
Note: The right side of the brain controls the left side of the body and vice versa.
Each hemisphere is also divided into 4 lobes: frontal (motor functions; pre-frontal - intellectual and executive functions); parietal (somato-sensation); temporal (auditory; some memory; location of the 2 amygdalae, which direct emotion, motivation and some cognitive functions); occipital (visual processing begins here)
The outermost layer is known as the cortex
Diencephalon
Sits right above the brain stem, between the 2 cerebral hemispheres, around the centre of the brain
4 parts: thalamus (relay between cerebrum and the rest of the NS; sleep, wakefulness); hypothalamus (homeostasis, links NS with endocrine system via the pituitary gland); epithalamus (pineal gland, melatonin); subthalamus (integration of skeletal muscle movements)
Brain stem
Located at the lower region of the brain, and is continuous with the spinal cord
Contains motor and sensor neurons that control the face and neck via cranial nerves
Comprises midbrain, pons, medulla oblongata
Regulates cardiac and respiratory functions, consciousness, sleep cycle, blood vessel widening, reflexes (vomiting, sneezing, coughing, swallowing)
Cerebellum (2/3 of all brain neurons are here)
Connected to the brain stem, at the back of the brain
Fine tuning voluntary movements and balance
Muscle memory
The spinal cord is a long, thin, tubular bundle of nervous tissue. It extends from the medulla oblongata of the brain stem to the lumbar region of the spine (the lower part, between the end of the ribs and the pelvis). Out of the spinal cord, 31 pairs nervous tissue extend out, connecting the PNS with the brain.
The retina can also be considered part of the CNS, as the retina and optic nerve extend from the diencephalon of the brain. As several major neurodegenerative disorders manifest here, this has also lead to it being considered part of the CNS, since it suggests a key link between eye and brain.
The peripheral nervous system (PNS)
The PNS is made up of nerves carrying information to and from the CNS. Its nerves are associated with the part of the CNS to which they connect; so, nerves are either cranial (brain) or spinal (spinal cord). There are 12 pairs of cranial nerves and 31 pairs of spinal nerves.
Of the 12 cranial nerves, 11 are part of the PNS and the other is the optic nerve. These 12 nerves mostly control smell, sight, eye movement, face, jaw, taste, hearing and movement of shoulders and neck. The vagus nerve is the longest cranial nerve and is connected to digestion and heart rate. It originates in the part of the brainstem called the medulla and extends all the way into the abdomen. This means it is one of the key connections between the brain and the digestive system, or GIT. (More on the gut-brain connection later.)
The PNS can be divided into the somatic nervous system and the autonomic nervous system. The somatic nervous system is the voluntary part, associated with movements and our sensory processing. The autonomic nervous system is involuntary, responsible for things such as our heart, blood pressure, breathing, digestion and more.
The autonomic nervous system can be divided into 3 parts:
Sympathetic nervous system (SNS)
Works with the endocrine (hormonal) system to trigger our ‘fight-or-flight’ response, via the amygdalae
Causes our pupils to dilate, our heart to speed up, our lungs to dilate and for more glucose to be sent to our muscles
Stimulates the adrenal glands to produce adrenaline (a neurotransmitter). The adrenal glands also release cortisol, which increases heart and lung capacity, constricts blood vessels and more
For more on the fight-or-flight response, you can look into the HPA axis
Parasympathetic nervous system (PSNS)
Controls our ‘rest-and-relax’ / ‘rest-and-digest’ functions
75% is comprised the vagus nerve
80% of its fibres are sensory (afferent), meaning it sends a lot of information to the brain
Controls pupil constriction, slowing down of the heart and digestion, amongst others.
Enteric nervous system (ENS) (largest part of the ANS)
Located along the digestive system
Produces more than 30 neurotransmitters and has more neurons than the spine. Its structure, function and chemical coding is similar to that of the brain and has thus been called ‘the second brain’.
The gut-brain axis is the two-directional flow of information between the CNS and the ENS. The communication here is complex and wide, as it involves the vagus nerve, the sympathetic nervous system, the hormonal (endocrine) system, the immune system, gut microbiota and more.
Importantly, the ENS and the gut-brain axis show us the direct impact that our digestive system can have on our brain. The foods we eat, the strength of our digestion, our gut microbiota and more can affect our mood, thinking, wellbeing, etc. (Studies have shown that the gut-brain axis can be improved via things like toning of the vagus nerve and meditation.)
In summary of the autonomic nervous system, the SNS is related to our ‘fight-or-flight’ response, the PSNS to our ‘rest-and-relax' state and the ENS to our digestion. The ENS communicates with the CNS via the PSNS and the SNS. (Note: the ‘freeze response’ involves activation of both SNS and PSNS.) A key fact that most fail to clarify in relation the SNS and the PSNS is that the distinction is mainly anatomical, defined by the vagus nerve and 3 other cranial nerves.
The nervous system in practice
Our nervous system is constantly switching between its parasympathetic (‘rest-and-relax’) and the sympathetic (‘fight-or-flight’) states. Each has its unique purpose and functions, as described above.
The problem occurs when we stay too long in the sympathetic mode through elevated stress, a poor diet, not enough or too much exercise, not enough sleep, shallow breathing and more. The ‘fight-or-flight’ response goes into overdrive, ready to defend us even though there is no danger, and, as a result, we feel unsafe. Many of us are not conscious that this is happening.
To check if you’re in an elevated ‘fight-or-flight’ mode, ask yourself if you constantly feel a niggling, anxious, fearful, doubtful feeling inside… If you feel an underlying pressure or the inability to fully relax most/ all of the time.
If this resonates, it might be time to implement tools that help to regulate your nervous system. By creating a balance between the sympathetic and parasympathetic modes, you are supporting your wellbeing, happiness, confidence, mental clarity and more.
6 tips for regulation your nervous system:
Going on a daily nature walk
Mindfully walking, without music or a podcast in your ears. Simply to the sounds of nature, become aware of your body and enjoy stepping one foot in front of the other.
Eating the right foods for your body and life
This means intuitively eating what’s right for you. This is about supporting your unique life and body.
Doing mindful exercise
Yoga, pilates or anything else that works for you. Working on the mind-body connection, and paying attention to how you feel each day before starting to exercise
Supporting the quality of your sleep
Essential oils, reduced screen time before bed, herbal teas and reading are all great for better sleep.
Weekly check-ins
Journalling, meditating or even a longer shower are great ways to look back at the past week, and create safety from within.
Centring through your breath
Slow down your breathing, take deeper inhales and longer exhales. Humming can also help.
Did any of these stand out to you? Imagine how you would show up if your nervous system felt safer and, as a result, you felt freer, more confident and more like yourself! Taking care of your nervous system is key to feeling amazing from within.
If you’re interested in 1:1 support in your healing, health and wellbeing journey, you can find my offerings here.
