Anatomy of Neurons and Impulse Conduction

Structure Of The Neuron And Central Nervous System. Address the following Short Answer prompts questions:-

1. In 4 or 5 sentences, describe the anatomy of the basic unit of the nervous system, the neuron. Include each part of the neuron and a general overview of electrical impulse conduction, the pathway it travels, and the net result at the termination of the impulse. Be specific and provide examples.

2. Answer the following (listing is acceptable for these questions):

o What are the major components that make up the subcortical structures?

o Which component plays a role in learning, memory, and addiction?

o What are the two key neurotransmitters located in the nigra striatal region of the brain that play a major role in motor control?

3. In 3 or 4 sentences, explain how glia cells function in the central nervous system. Be specific and provide examples.

4. The synapse is an area between two neurons that allows for chemical communication. In 3 or 4 sentences, explain what part of the neurons are communicating with each other and in which direction does this communication occur? Be specific.

5. In 3–5 sentences, explain the concept of “neuroplasticity.” Be specific and provide examples.

References:

Stahl, S. M. (2021). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (5th Ed.) Cambridge University Press.
Chapter 1, “Chemical Neurotransmission” (pp. 1-28)

Anatomy of Neurons and Impulse Conduction

The neuron, the fundamental unit of the nervous system, is a highly specialized cell responsible for transmitting electrical and chemical signals. It comprises distinct parts, each contributing to its overall function. The cell body, or soma, houses the nucleus and other organelles vital for cell metabolism. Dendrites, branching extensions, receive incoming signals from other neurons or sensory receptors. The axon, a long, slender projection, conducts electrical impulses away from the cell body. Myelin sheath, insulating the axon, enhances signal conduction speed. Impulses travel along the axon, initiated by depolarization due to incoming signals. At the axon terminals, neurotransmitters are released into the synapse, which is the small gap between neurons. These chemicals transmit the signal to the next neuron or target cell. For instance, when a sensory neuron in the skin detects a temperature change, the signal is transmitted along its axon to the spinal cord, eventually reaching the brain, resulting in the perception of temperature.

Subcortical Structures and Their Functions

The subcortical structures encompass several essential components within the brain. The hippocampus, a seahorse-shaped structure, is crucial for learning and memory consolidation. It aids in the formation of long-term memories and spatial navigation. The nucleus accumbens, part of the ventral striatum, plays a pivotal role in reward, motivation, and addiction. It is engaged in the brain’s reward circuitry, contributing to the experience of pleasure and reinforcement.

Neurotransmitters in Nigra Striatal Region

The nigra striatal region is a critical hub for motor control. Two major neurotransmitters, dopamine and gamma-aminobutyric acid (GABA), are prominent in this region. Dopamine is involved in regulating movement and reward-based behaviors. Its deficiency leads to Parkinson’s disease. GABA, on the other hand, is inhibitory and plays a crucial role in controlling the excitability of neurons, contributing to the fine-tuning of motor coordination.

Function of Glia Cells

Glia cells, often referred to as “glial cells,” are essential support cells in the central nervous system. They provide structural and metabolic support to neurons. Astrocytes, a type of glia cell, maintain the chemical environment for neuronal signaling by regulating neurotransmitter levels. They also contribute to the blood-brain barrier, protecting the brain from harmful substances. Microglia, another type, are the immune cells of the brain, monitoring and responding to any signs of injury or infection.

Synaptic Communication and Direction

Communication between neurons occurs at synapses, where an axon terminal of one neuron meets the dendrite of another. This communication is chemical, involving neurotransmitters released from the axon terminal. These neurotransmitters cross the synaptic gap and bind to receptors on the dendrite, transmitting the signal. The direction of communication is unidirectional – from the presynaptic neuron (the sender) to the postsynaptic neuron (the receiver).

Neuroplasticity: Adaptable Brain Wiring

Neuroplasticity, often termed “brain plasticity,” refers to the brain’s ability to reorganize its structure, function, and connections in response to experiences, learning, and environmental changes. It underscores the brain’s adaptability and capacity to recover from injuries. For instance, in cases of brain injury, healthy regions may take over functions of damaged areas. Learning a new skill, such as playing an instrument, involves the strengthening of neural pathways as the brain adapts to the new activity’s demands.

References

Stahl, S. M. (2021). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (5th Ed.) Cambridge University Press. Chapter 1, “Chemical Neurotransmission” (pp. 1-28).
Kim, E. J., Kim, E. S., Covey, E., Kim, J. J., & Schneiderman, I. (2018). Dopamine and the Nucleus Accumbens Play a Role in Mediating Appetitive Olfactory Learning in Rats. Frontiers in Behavioral Neuroscience, 12, 278.
Gogolla, N., Takesian, A. E., Feng, G., Fagiolini, M., & Hensch, T. K. (2014). Sensory Integration in Mouse Insular Cortex Reflects GABA Circuit Maturation. Neuron, 83(4), 894-905.
Herculano-Houzel, S., & Lent, R. (2005). Isotropic Fractionator: A Simple, Rapid Method for the Quantification of Total Cell and Neuron Numbers in the Brain. Journal of Neuroscience, 25(10), 2518-2521.