Lecture: The Neuron
Reading Assignment 5:
Neuron: Basic Unit of the Nervous System
Click for objectives for Reading Assignment 5

Summary:
The fifth reading assignment introduces students to the primary means by which the body is able to communicate information within itself. To address the many issues that the body must transmit information about, two separate systems exist. These systems are the Nervous System and the Endocrine System. The Nervous and Endocrine Systems communicate information in two completely isolated systems in the body. The body takes advantage of these distinct and isolated systems and uses it to its advantage. Some of the chemicals used in the Nervous System to communicate information are identical to those used in the Endocrine System. There is no downfall to using the same chemicals, they will remain in the appropriate and isolated systems in a healthy human being.

The first system that will be discussed is the Nervous System, which is made up of Neurons. In this course, we will distinguish between three different types of Neurons. This distinction is functional, as it is based only on where the Neurons receive their information and where they are sending their information. The three different types are the: Sensory of Afferent Neuron, Interneuron, and Motor or Efferent Neuron. While these three types of neurons may differ in their functions within the Nervous System, they do not differ in their structure or Anatomy.

For the sake of a discussion in Psychology, the Anatomy of the Neuron can be broken down into seven parts. The Cell Body surrounds the Nucleus and is where the Dendrites and Axon extend from. The Myelin Sheath and the Terminal Buttons are important parts of the Neuron that are responsible for the act of communication.The last part of the Anatomy of the Neuron is the Synapse or Synaptic Cleft, which is not a part of the Neuron but rather a small space or void that exists between neurons. The Synapse or Synaptic Cleft and is essential for communication.

To fully understand Neuron communication, it is important to understand the three states of a Neuron. Immediately after a Neuron communicates by sending a signal, it will momentarily return to its Resting Potential State. When further stimulation occurs, the Neuron fluctuates from a resting state and is said to be in a Graded Potential State. If the cumulative fluctuations are sufficient enough to create a polarized state in the Neuron of -50 mV, it will send a signal and is said to be in the Action Potential State.

In the Action Potential State chemicals called Neurotransmitters are released into the Synapse. In this course, we distinguish between six Neurotransmitters; they are as follows: Glutamate, GABA, Serotonin, Acetylcholine, Endorphins, and Dopamine. Each Neurotransmitter initiates unique functions within the human body when they fuse with the appropriate Receptor. Since all Neurotransmitters cannot fuse will all Receptors, the “lock and key analogy” is frequently used to describe these two concepts – as every key cannot open every door.

The second system that will be discussed is the Endocrine System, which is made up of glands instead of neurons. The glands of this system secrete Hormones into the bloodstream. This contrasts how Neurotransmitters are released into the Synaptic Cleft, which was mentioned earlier. In this course, we will only identify four major glands of the Endocrine System; they are as follows: the Gonads, Thyroid Gland, Pituitary Gland, and Adrenal Gland.


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Barnes #RA05

References:
Textbooks
A. Wilson, J. F. (2003). Biological Foundations of Human Behavior (Instructors Ed.). Thomson, Inc.
B. Klein, S. B. (2000). Biological Psychology. Prentice Hall, Inc.

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