Sympathetic and Parasympathetic responses

Sympathetic Responses are also known as the "fight-or-flight" response. This response is important in emergencies that casue stress that require us to either fight or run away.
During activation of the sympathetic division, the release of hormones by the adrenal medullae create a set of responses. These responses include:
-Dilation of the pupils
- Increase in heart rate, force of heart contraction and blood pressure
- The airways dilate, allowing faster movement of air into and out of the lungs
-Blood vessels that supply kidneys and gastrointestinal tract constrict
-Blood vessels that supply organs involved in exercise or fighting off danger
-skeletal muscle, cardiac muscle, liver, and adipose tissue dilate, allowing greater blood flow through these tissues.
-The liver increases breakdown of glycogen to glucose and adipose tissue. This increases the breakdown of triglycerides to fatty acids and glycerol which raises blood levels of these molecules for greater ATP production.
-Release of glucose by the liver increases blood glucose level for greater ATP production
-Processes that are not essential for meeting the stressful situation are inhibited.


In regards to this last effect. I learned that some functions turn off or even stop during the fight or flight response. An example that I learned is that your digestive secretions may actually slow down. I guess if your about to get robbed and you want to turn around and run away as fast as you can, your body may be trying more to keep up with your faster breathing and faster body movements to get you away from the dangerous scene. I never really thought about this before but after reading and learning about it, it makes sense. It's pretty interesting how our body works and responds to our experiences and to our internal and external environment.

I also learned that the parasympathetic division is also referred to as the rest-and-digest division. This is important is non emergency situations. It enhances the rest and digest activities. This means that the parasympathetic responses support body functions that conserve and restore body energy during times of rest and recovery. There are five parasympathetic responses that are stimulated by this division. These include: salivation, lacrimation, urination, digestion, and defecation. These five responses increase when activated. There are also three more responses that have a decrease effect. During this division, there is a decrease in heart rate, diameter of airways known as bronchoconstriction, and a decrease in diameter of the pupils known as constriction.

A good way for me to remember when these responses come in to play is to put it into my real life experiences. When I thought about what would happen if I came home and ran into a robber, or if I was startled by one, this would be the type of situation where my sympathetic nervous system would be called into action. This system would use energy, increase my blood pressure, increase my heart rate and slow down my digestion. It would also help my run as fast as I can out of there!

Now imagine if my day was much different than this. If it was a beautiful sunny day and things were pleasant at work and I got home early and decided to sit down and relax on the couch, my parasympathetic nervous system would kick in. With my body now relaxing, it would also be time for my blood pressure to decrease, my heart rate to slow down and my digestion can start.

These responses remind me just how much our insides are effected by whats going on, on the outside or in our daily lives. It got me thinking how things like stress effect us internally and trigger responses. I think being aware of how much control we actually have over our health can help us improve the quality of our daily living.