Sympathetic Nervous System
The autonomic nervous system is made up of the brain and the spinal cord and can be divided into two different divisions. These divisions are called the sympathetic nervous system, and the parasympathetic nervous system. These two divisions typically have opposite actions from one another.
The sympathetic nervous system division is composed of nerves that branch off from the spinal cord sections which include the thoracic vertebrae and the lumbar vertebrae. Within these nerves you will find sympathetic ganglia which are neurons that help conduct impulses to the other organs of our body. These are pre-ganglionic and post-ganglionic. This action is described by Wikipedia in the following words: “The shorter preganglionic neurons originate from the thoracolumbar region of the spinal cord specifically at T1 to L2~L3, and travel to a ganglion, often one of the paravertebral ganglia, where they synapse with a postganglionic neuron. From there, the long postganglionic neurons extend across most of the body. At the synapses within the ganglia, preganglionic neurons release acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons. In response to this stimulus postganglionic neurons—with two important exceptions—release norepinephrine, which activates adrenergic receptors on the peripheral target tissues. The activation of target tissue receptors causes the effects associated with the sympathetic system.” The sympathetic nervous system is what is responsible for the fight or flight response to outside stimuli. For an example, if you are out taking a walk on a nice day and come across a large dog that is not leashed, your heart rate will probably dramatically increase pretty quickly and you could become a bit sweaty and experience feelings of anxiousness and fear. This is your sympathetic nervous system working and responding to stress. It is getting your body amped up in preparation for survival mode. Besides the fight or flight response, your sympathetic nervous system is also responsible for the dilation of your pupils, constricting blood vessels, relaxing airways, increased heart rate, stimulating secretions of epinephrine and norepinephrine, relaxing the urinary bladder, increased sweating, and stimulating orgasm of the reproductive organs.
Reference
Bobick, J., & Balaban, N. (2008). The Handy Anatomy Answer Book Includes Physiology. Visible Ink Press 43311 Joy Rd., #414 Canton, MI 48187-2075: Visible Ink Press.
The Editors of Encyclopædia Britannica (2016). Sympathetic nervous system | anatomy. In Encyclopædia Britannica. Retrieved from https://www.britannica.com/science/sympathetic-nervous-system
Sympathetic nervous system (2016). . In Wikipedia. Retrieved from https://en.wikipedia.org/wiki/Sympathetic_nervous_system
Citations, Quotes & Annotations
Sympathetic nervous system (2016). . In Wikipedia. Retrieved from https://en.wikipedia.org/wiki/Sympathetic_nervous_system
"The shorter preganglionic neurons originate from the thoracolumbar region of the spinal cord specifically at T1 to L2~L3, and travel to a ganglion, often one of the paravertebral ganglia, where they synapse with a postganglionic neuron. From there, the long postganglionic neurons extend across most of the body. At the synapses within the ganglia, preganglionic neurons release acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons. In response to this stimulus postganglionic neurons—with two important exceptions—release norepinephrine, which activates adrenergic receptors on the peripheral target tissues. The activation of target tissue receptors causes the effects associated with the sympathetic system." (“Sympathetic nervous system,” 2016)
