Communication, Control, Integration

The major subdivisions of the Human Nervous System and five main types of Glia.

Two main subdivisions comprise the nervous system, including the peripheral nervous system (PNS) and the central nervous system (CNS). The CNS consists of the brain and the spinal cord, while the PNS is made up of the ganglia and nerves (Mader & Windelspecht, 2017). The glial cells are astrocytes, microglia, oligodendrocytes, Schwann, and ependymal cells (Jäkel & Dimou, 2017).

Difference between an axon and a dendrite

Dendrites are branched projections of nerve cells. They are extensions of neurons and conduct electrochemical signals they receive from neighboring cells (Mader & Windelspecht, 2017). The signals they receive are carried towards the cell body. Axons are nerve fibers that are slender and elongated. Similar to dendrites, they are projections of neurons. The primary role is to conduct impulses away from the cell body of nerve cells (Mader & Windelspecht, 2017).

Three structural categories of neurons

Structural classification is based on the number of processes extending out from the soma. They are classified into multipolar neurons with three or more processes, bipolar neurons with two processes, and unipolar neurons with one process (Mader & Windelspecht, 2017).

Three functional categories of neurons

Functional classification is based on the direction of conduction of the signal concerning the CNS. On that note, sensory neurons conduct signals from receptors toward the CNS, while motor neurons conduct impulses away from the CNS to the effector cells. Additionally, interneurons are involved in signal integration between sensory and motor neurons (Mader & Windelspecht, 2017).

Essential Components of a Reflex Arc

A reflex is a predictable and involuntary response, while a reflex arc is a neural pathway involved in the involuntary response (Mader & Windelspecht, 2017). The components of the reflex arc include sensory receptors, sensory neurons, interneurons, motor neurons, and effector organs (Mader & Windelspecht, 2017).

Circumstances under which a nerve fiber be repaired

Nerves can be damaged due to trauma. Nerves can be repaired if the damage is not serious, scarring has not occurred, and the neurilemma and soma remain intact (Mader & Windelspecht, 2017).

The most abundant positive ion on the outside and inside of the plasma membrane is in a resting neuron. List of events that bring about the initiation of an action potential.

Potassium is the major positive ion in the cell, while sodium ions are the major positive ions outside the cell (Mader & Windelspecht, 2017). An excitatory signal from a presynaptic neuron initiates an action potential. This leads to releasing a neurotransmitter from the presynaptic neuron (Mader & Windelspecht, 2017). The neurotransmitter then attaches to postsynaptic cell receptors, resulting in the opening of ion channels (Mader & Windelspecht, 2017). The three stages of an action potential are depolarization, repolarization, and hyperpolarization.

 Difference between excitatory neurotransmitters and inhibitory neurotransmitters

Excitatory neurotransmitters promote the generation of an action potential on the presynaptic, while inhibitory neurotransmitters prevent the generation of action potential (Mader & Windelspecht, 2017).

References

Jäkel, S., & Dimou, L. (2017). Glial cells and their function in the adult brain: A journey through the history of their ablation. Frontiers in Cellular Neuroscience, 11. https://doi.org/10.3389/fncel.2017.00024

Mader, S., & Windelspecht, M. (2017). Human biology. McGraw-Hill Education.

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At least 400 words:

List the major subdivisions of the human Nervous System. Mention the five main types of Glia.

What is the difference between an axon and a dendrite?

What are the three structural categories of neurons?

What are the three functional categories of neurons?

What are the essential components of a Reflex Arc?

Under what circumstances can a nerve fiber be repaired?

In a resting neuron, what positive ion is most abundant outside the plasma membrane? What positive ion is most abundant inside the plasma membrane? List the events that lead to the initiation of an action potential.

How do excitatory neurotransmitters differ from inhibitory neurotransmitters?