Beh 225 Appendix C

Part I

Neurons are responsible for communication between the brain and the nervous system. Dendrites send chemical responses to the neurons which cause a nerve impulse called action potential. These nerve impulses then travel to the end of the axon. The axon is a nerve fiber that conducts electrical impulses away from the neurons cell body. The impulses then travel through the synapse and into the next nerve cell. The neurons do not directly touch. The electrical impulses must cross a gap known as a synaptic cleft to reach another neuron. The presynaptic neuron which is located on the side of the synaptic cleft is responsible for sending the messages. Receiving the messages on the other side is the postsynaptic neuron. Synaptic vessels are small sacs that contain neurotransmitters which act as chemical messengers to other neurons. When the neural impulses reach the synaptic vessels, it causes them to release chemicals. These chemicals travel to the next cell. The molecules then make contact with receptor sites which are special molecules inside the receiving neuron. The neurotransmitter molecule must match up with a postsynaptic membrane with a matching receptor site in order to receive any messages. Each neurotransmitter has a specific effect on specific nerve circuit. Neurotransmitters are either excitatory or inhibitory. Excitatory neurotransmitters communicate a nerve impulse while inhibitory neurotransmitters prevent communication of nerve impulses. All of these processes carry information throughout the human body.

Common neurotransmitters are dopamine and acetylcholine. Acetylcholine is an excitatory neurotransmitter that helps transmit impulses between motor neurons. Dopamine neurotransmitters inhibit nerve impulses in the motor neurons. Both of these neurotransmitters are responsible for controlling motor functions. Other neurotransmitters include serotonin and noradrenalin. Serotonin is responsible for functions such as control of appetite, mood,...