I’m running on a trail in a nature reserve outside of Montpelier after a long day working on my feet. My stomach rumbles with hunger and my lips feel parched from not drinking enough water. There’s a strong breeze in the air and I have goose bumps on my arm as my body hasn’t warmed up to the jogging yet. As I come around a turn in the trail, I hear a tree cracking above my head that distracts my attention. I look up to see what made the sound and then slip on a rock and start to fall forward. My body responds by recoiling and I slide and catch my fall by landing on my feet and hustling out of the way of a large branch falling from the tree above. Whhhattttt a system! My nervous system has my back. It's a dynamic, split-second acting, brilliant living presence within me that is constantly receiving input from all kinds of sources and sorting through large amounts of information on a moment to moment basis, including data stored in my memory banks about the meaning of these sounds and sensations and other stimuli. My luscious nervous system integrates this seemingly unrelated information quickly and this allows me to react in time. Let’s take a look at this extraordinary part of our body. The nervous system receives information from our senses. Then it integrates the different pieces of information from many different sources and makes sense of it as a whole. Instantaneously it sifts through mountains of data and comes up with a plan or course of action. What’s so fascinating to me is that all this is going on automatically without requiring my attention or even my conscious decision making. However, the nervous system can bring selected information to the level of my conscious awareness. In conjunction with the endocrine system, the nervous system works to support allostasis and allows us to feel emotions, be aware of ourselves and exert conscious control over the extraordinary diversity of our physical movements and experiences. The nervous system consists of the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and the spinal cord. This system receives, processes, stores and transfers information. The peripheral nervous system represents components of the nervous system that lie outside the central nervous system. See picture below. The peripheral nervous system has two functional subdivisions: the sensory division of the peripheral nervous system (see yellow side of diagram) carries information to the brain and spinal cord and the motor division (see purple side of diagram) carries information from the central nervous system. The motor division of the peripheral nervous system is further subdivided as you can see in the diagram above. The somatic division controls skeletal muscles while the autonomic division controls smooth muscles, cardiac muscles and glands. Additionally, the autonomic division has two subdivisions called the sympathetic and parasympathetic divisions. These two parts work antagonistically to slow us down to rest and digest or fire us up to accomplish our mission in the world or escape from a falling tree. While the sympathetic and parasympathetic oppose each other, they essentially work together to accomplish the automatic, subconscious goal of allostasis. The sympathetic division of the autonomic nervous system arouses the body. Preganglionic motor neurons of the sympathetic division originate in the thoracic and lumbar regions of the spinal cord. Many of them attach to a chain of sympathetic ganglia that lie alongside the spinal cord. Because the sympathetic division is are well connected to each other, the sympathetic division tends to produce a unified response in all organs at once, transmitting signals that prepare the body for emergencies and situations requiring high levels of mental alertness or physical activity. This could include fighting or running away from danger (“flight or fight”) and even play or sexual activity. The sympathetic division is in charge of increasing heart rate and respiration, raising blood pressure, dilating the pupils and other effects that help you detect and respond quickly to changes in your environment. In addition, the sympathetic division also reduces blood flow to organs that do not help you cope with an immediate emergency, such as the intestines and kidneys and this division inhibits less important body functions such as digestion and production of saliva. This is why it’s common to get a dry mouth during highly stressful moments. See my drawing below for a visual of the divisions of the autonomic nervous system. The parasympathetic division predominates during relaxation. Preganglionic neurons of this division originate either in the brain or from the sacral region of the spinal cord. The ganglia where the preganglionic neurons synapse with the postganglionic neurons is generally some distance from the central nervous system and may even be in the target organ itself. The parasympathetic division predominates in situations in which one is relaxed. This division transmits signals that lower heart rate and respiration, increase digestion, permit defecation and urination, and exerts calming, restorative effects that counteract the fight or flight stimulation of the sympathetic division. Curiously, parasympathetic nerves are also responsible for the vasodilation that causes erections in the penis and swelling of the labia and erection of the clitoris in the vagina. Overall, it appears that the actions of the sympathetic and parasympathetic divisions oppose each other work. But their seemingly antagonistic actions work together to accomplish the automatic, subconscious maintenance of allostasis. Both systems are intimately involved in the feedback loops that help to make allostasis happen. As we’ve looked at, the nervous system coordinates all body functions, enabling a person to adapt to changes in internal and external environments and thus maintain allostasis. This system has two main types of cells - neurons, that act as conducting cells and neuroglia, that act as supporting cells. Our dear neuron is the basic unit of the nervous system. This highly skilled and specialized conductor cell receives and transmits electrochemical nerve impulses. Let’s take a look at the various parts of this mystical unit. Axons and dendrites are threadlike nerve fibers that extend from the central cell body and transmit signals. In particular, the axons conduct nerve impulses away from cell bodies and are covered in a white, fatty segmented covering called a myelin sheath. Dendrites on the other hand are short, thick, branched extensions of the cell body that receive impulses from other cells and conduct information on toward the cell body. Neurons receive information in the form of electrochemical information from other neurons at the cell body. If the incoming information is of the right kind and is strong enough, the neuron responds by generating an electrical impulse of its own where the dendrite joins the axon. The impulse is then transmitted from one end of the axon to the other, bypassing the cell body. The impulse stimulates synaptic vesicles in the presynaptic axon terminal. A neurotransmitter substance is released and diffuses to bind to specific receptors. This stimulates or inhibits stimulation of the postsynaptic neuron. The reflex arc is the transmission of sensory impulses to a motor neuron via the dorsal root. The motor neuron delivers the impulse to where it needs to go - a muscle or gland, which then produces an immediate response. All this happens in an instant. Incredible! Reflection:
Because the nervous system is so complex and controls so many bodily functions, disorders of the nervous system can be particularly debilitating. Trauma, infections, and brain tumors can cause major injury as well as disorders of neural and synaptic transmission like Parkinson’s disease, a progressive, degenerative disorder that strikes nearly 50,000 people a year in North America, most over age 55. Symptoms include stiff joints and muscle tremors in the hands and feet. Eventually people with Parkinson’s lose mobility; they may also become mentally impaired. My father died this past November after battling this disease for nine years. It was a grueling and devastating decline and it's been hard but interesting to read more about it during this unit. Parkinson's is caused by the degeneration of dopamine-releasing neurons in the area of the midbrain that coordinates muscle movement. The shortage of dopamine impairs the ability to perform smooth, coordinated motions. My father was prescribed L-dopa, a drug that the body converts into dopamine, but this does not slow the loss of neurons. Even taking the medication for years my father rapidly lost his ability to feed himself, walk and eventually talk. It was heart breaking to watch him want to do things but his body wouldn’t respond. I could almost see the lack of electrical impulse. Watching my father suffer for so long and feeling powerless to do anything about it is one of the reasons I decided to delve deeper into my interest in and love for herbal medicine. I wish I had known that American Skullcap could have eased his symptoms and that there are many other herbs that support the neural brain forest that is rich with memories, emotions, dreams and desires not to mention all the control center systems that I mentioned previously. Our brain controls how we see the world, taste our food, hear music, smell aromas and absorb the wonder of the earth around us. The brain and nervous system ecosystem should not be taken for granted. As we discussed before, neurotransmitters are the substances responsible for transmitting electrical impulses across the neural synapses. When their job is done, enzymes break down the neurotransmitters. Reuptake inhibitors (including the well-known antidepressant selective serotonin reuptake inhibitors SSRIs) inhibit the breakdown of specific neurotransmitters so that more of those neurotransmitters will be present in the body. Neurotransmitters do a wide range of things, and an excess or deficiency of them plays a role in many different diseases. Acetylcholine (ACh) is a major transmitter for basic body functions including contraction and control of muscles. Low ACh levels are associated with Alzheimer’s, dementia and Parkinson’s. I was delighted to discover many of our mint-family brain-boosting herbs like sage, rosemary, lemon balm, and mint for example boost ACh levels by inhibiting the enzyme that breaks it down. I also strongly believe that diet, lifestyle and well-being have an even greater effect as the foundations of health and vitality when it comes to brain health. My father spent a lot of his life extremely stressed out. He also ate very poorly and didn’t exercise and often felt distant from his family and community. Quality food, exercise, community, meditation - these are all important ways to support ourselves on so many levels including strong brain health. Additionally, our brain requires voluminous blood flow to function properly. Blood delivers essential nutrients, including oxygen and glucose, shuttles out our waste and transports hormones. Oxidation and inflammation in the body inhibit blood flow and create blockages in the neural roadways. Some damage may not become obvious until one’s later years, as issues can take decades to accumulate. Herbalism offers us an alternative to the anti-inflammatory drugs so commonly prescribed as well as eating quality food, keeping stress levels down, getting enough sleep and exercise. Other herbs to consider: Indians have revered Gotu Kola as a memory and brain tonic for at least 2,500 years and Ginkgo, turmeric, berries (especially blueberries) and green tea have all been revered for their antioxidant ways. Bacopa (the Ayurvedic creeping water plant) promotes memory and focus and holy basil, ashwagandha, reishi, lemon balm and rhodiola have all been renowned for their antistress, adaptogenic effects. I was having such a hard time caring for myself while caring for my father when he was sick that it was really challenging for me to begin bringing in herbal remedies for him. I try not to be hard on myself about the things I could have done and how much more I could have been there for him. I did the best I could. I feel grateful to have been by his side the last few days of his life, spritzing rose water on his face, swabbing his mouth with fresh water and relighting the sage smudge in the corner of the room - small but potent forms of love medicine offerings. Perhaps someday I’ll be able to offer some herbs to others struggling with similarly demonic nervous system disorders. Ufffffff.
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AuthorThe adventures, studies, and musings of a student at the Vermont Center for Integrative Herbalism.
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