Wednesday, March 4, 2009
Anatomy and Physiology Week 6
This week we discussed the autonomic nervous system. It is an involuntary part of the nervous system which carries efferent impulses away from the brain. It is made up of smooth and cardiac muscle and glands. It has two different parts, the parasympathetic(feed and breed regulator) and the sympathetic(fight or flight). Part of the parasympathetic has two neurons. Neuron number one is the preganglionic cell and it has a long axon, neuron number two is the post ganglionic cell and has a short axon. In the sympathetic there are also two neurons, but neuron number one(the preganglionic cell) has a short axon and neuron number two(the post ganglionic cell) has a long axon. The parasympathetic impulse carriers are the III(oculomotor), VII(facial), IX(Glossopharangeal) and X(vagus). We also discussed the eye and its layers. The three layers of the eye we discussed were the sclera(fibrous) which is vascular, the choroid(pigmented) which is also vascular, and the retina(visual) which is not vascular. We learned that the parasympathetic nerve responds to bright light and the sympathetic nerve responds to dim light.
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You know, its pretty crazy that without really thinking about it, our body is constantly at work in keeping us alive!! There are so many crazy things that our body does that when it all comes together, you have to see that we are extremely complex beings. The fact that our body can still control our breathing when we are asleep, keep our heart pumping, and make sure that our metabolism and all the bodies other functions are still running, is pretty complex. It is also interesting how our body can adjust to different stimulation that we are presented with. As Katie pointed out, the parasympathetic system is responsible in responding to bright light, and the sympathetic nerve responds to dim light. Both parts of our autonomic nervous system are constantly working together to adjust to these different stimulations that we face everyday, The fascinating part of it all is that we don't have to remind ourselves to keep our heart pumping, or tell ourselves when to inhale and exhale. If this were the case, I'm pretty sure living just wouldn't be as fun :)
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