The two branches of the Autonomic Nervous System are the sympathetic division and the parasympathetic division. The main process of the sympathetic division is to stimulate the fight-or-flight response in the body, which means it is in charge of stimulates actions. In the sympathetic system, epinephrine and norepinephrine are the main neurotransmitter. In the sympathetic system, there are two neurons involved in transmission and they are the pre-ganglion and post-ganglion. The preganglionic fibers are short and they originate in the brain stem and sacral segments of the spinal cord. The preganglionic neurons synapse with a postganglionic neuron once they reached a ganglion. The postganglionic fibers, which are long, then expand through most of the body. During the synapse, the preganglionic neurons discharge a neurotransmitter called acetylcholine. The acetylcholine triggers nicotinic receptors on the postganglionic neurons, which leads to postganglionic neurons releasing norepinephrine on the tissue, with two exceptions to this. The norepinephrine triggers adrenergic receptors, which is what causes the outcomes related to the sympathetic …show more content…
They are found in the plasma membrane. Ion channels open and close depending on the mechanical or chemical signals. Ion channels manage the flow of ions across a cell membrane. A good example of an ion channel receptor is the nicotinic acetylcholine receptor. The neurotransmitter, acetylcholine, is what causes the channels to be opened. Once the channels open, sodium and potassium ions go into the cell, resulting in depolarization in muscle cells. The changes that occur in the electrical potential also lead to other channels to be opened. What eventually results in a muscle contraction is the opening of the voltage-gated calcium