Posted 08/19/2010
In the previous blog I discussed how the human body is comprised of many systems and how they all interact. Today I will discuss the autonomic nervous system.
The human nervous system can be divided into several connected systems that function together. The human nervous system has two major divisions, the voluntary and the autonomic systems. The voluntary system is concerned mainly with movement and sensation. The autonomic system controls functions over which we have less conscious control or that happen automatically. These include the digestion of food, blood pressure, heart rate, and respiration. There are three parts to the autonomic nervous system: the sympathetic system, the parasympathetic system and the enteric system. For our purposes today, I will discuss the sympathetic, otherwise known as the “fight or flight” system, and the parasympathetic or “rest and repair” system and their interactions.
The sympathetic and parasympathetic systems have opposite functions. When we are under stress, the sympathetic system raises our heart rate, blood pressure, and respiration so that we can either run away from (flight) or “fight” whatever is threatening us. Generally, when the threat is dealt with, the parasympathetic system restores and/or slows down our heart rate, blood pressure and respiration.
Relatively few people today have a strong, balanced autonomic system. Most people favor their sympathetic branch. These people tend to be more outgoing, have strong type-A personalities, are aggressive, and have faster metabolisms. They tend to be more prone to anxiety, irritability, and nervousness. Parasympathetic individuals tend to be more laid back, have type-B personalities, are lethargic, fatigued, have slower metabolisms, and often times are prone to depression.
As a way to understand how the sympathetic and parasympathetic nervous systems function together I will compare how automotive engineers have provided the same components in the car that are needed to prevent the car from running out of gas or overheating, and compare that with how the body is regulated with the help of the autonomic nervous system. My next blog will consider a common example of how the autonomic nervous system is regulated using the analogy of the car.
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Posted 07/12/2010
There are many systems within the body that need particular guidance to optimize function. Let us assume that your body’s systems are comparable to a car. You have a new car, you expect it to run smoothly with minimal problems, which it does, for some time. You drive your car day in and day out, and it works. After a period time, you fail to provide proper care and your car starts to break down. It has a starting problem, it starts giving less mileage per gallon of gas, the paint starts to fade, the upholstery rips, and doors get dinged, so on and so forth. What do you do if your car gets old and starts giving you trouble? You buy a new one! As in this analogy, your car is actually your body. Unfortunately, you cannot change your body for a new one. You are stuck with it for your entire life. If your car starts having problems, you may have to push-start it every time you want to go somewhere. If people give you strange looks because your muffler is dragging, you have a flat tire, or you have various dents and door dings, you put up with it. If it costs a lot of money to provide you with temporary fixes, which won’t last but several months, you put up with it. How you wish you knew from the beginning that you were stuck with this car for life! You would have taken better care of the car! You would not have been stuck with a lemon! Likewise, you must take care of your body to prevent breakdowns. Unfortunately, your body has to carry on through the mechanical failures that life presents and get occasional fixer-uppers to continue working. In other words, you can’t replace your entire body because it is simply not possible!
Similar to a car, there are several systems in the body that need to be assessed, watched, and trained in order to run in the best possible way day in and day out. A performance check on your car may reveal concerns with the fuel system, the engine’s horsepower, the aerodynamics, the chassis and suspension, the tire pressure of all four tires, the heat regulation, and a countless number of other systems in the car. Like a car, all systems of the body must be working together to optimize function. Having too much power without enough flexibility can lead to potential injury.
Again using the car analogy, the musculoskeletal system (muscles and bones) is similar to the chassis, suspension, and wheels of a car, whereas the cardiovascular system can be likened to the car’s engine. The cardiovascular system is comprised of the heart, lungs, and blood pathways. It transports oxygen (i.e. gas) to the various parts of the body. Often times we are mainly concerned with the “engine” and how the car runs, and pay little attention to the car “body.” Rather than constantly trying to improve the cardiovascular system to handle higher workloads, why not also try to improve the musculoskeletal system? Then, when given a larger workload such as a long destination, you will get much better gas mileage because the musculoskeletal system is strong. This can be done by improving the car’s suspension, transmission, and wheels, as well as making sure that each is properly maintained and aligned so that the car will be more efficient at a given speed.
This analogy will continue to be discussed over the next couple of months. The purpose of this discussion is to help you understand the interaction between systems. The importance of body systems and their relationship as it relates to mechanics will be discussed. Just as with the case of our car, we may need occasional tune-ups and adjustments to avoid injury and breakdowns.
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