Biological Psychology: Neurons, Glial Cells, and Neural Communication

Biological Psychology

Neurons: The Brain’s Communicators

Neurons are the fundamental units of the nervous system, responsible for transmitting information throughout the brain and body. Their specialized structure allows for efficient communication via electrical and chemical signals.

• Definition: Neurons are nerve cells specialized in communication with each other.

• Role: They serve as the building blocks of the nervous system.

• Function: Neurons transmit information in the form of electrical signals known as action potentials.

• Example: Sensory neurons carry information from sensory organs to the brain, while motor neurons transmit commands from the brain to muscles.

Neural Components

Neurons have distinct structural components that facilitate their function in communication.

• Cell Body (Soma): Contains the nucleus and builds new cell components.

• Dendrites: Branchlike extensions that receive information from other neurons.

• Axon: Long, thin 'tail' that transmits information away from the cell body.

• Axon Terminal: Knob at the end of the axon containing synaptic vesicles filled with neurotransmitters.

• Synapse: The junction between neurons where communication occurs via neurotransmitter release.

• Mnemonic: "Dendrites listen, axons speak!"

Glial Cells

Glial cells are non-neuronal cells that provide support and protection for neurons. They are essential for maintaining the health and function of the nervous system.

• Definition: 'Glial' means glue; these cells are plentiful in the brain.

• Functions:

  • Support neuronal function (e.g., produce myelin).

  • Feed and protect neurons.

  • Maintain homeostasis and provide insulation.

• Example: Oligodendrocytes in the central nervous system produce myelin, a fatty substance that insulates axons.

Myelin and Multiple Sclerosis

Myelin is a fatty insulation produced by glial cells that surrounds axons, increasing the speed and efficiency of electrical signal transmission.

• Function: Myelin allows for rapid conduction of action potentials along the axon.

• Clinical Relevance:

  • Multiple Sclerosis (MS): A disease characterized by the loss of myelin, resulting in erratic neural signaling and impaired motor and sensory function.

How Does a Neuron Fire?

The process by which neurons transmit electrical signals is called the action potential. This involves several steps:

1. Resting Potential: The neuron is polarized, with a negative charge inside and a positive charge outside. The membrane is selectively permeable, preventing sodium ions (Na+) from entering.

2. Action Potential: When stimulated, the neuron depolarizes as Na+ channels open and sodium ions rush in, reversing the charge. This brief electrical charge travels down the axon, transmitting the message.

3. Repolarization: Potassium ions (K+) flow out, restoring the negative charge inside the neuron.

4. Return to Resting Potential: The neuron resets its ionic balance.

5. Refractory Period: A brief period during which the neuron cannot fire again, regardless of stimulation.

All-or-None Law: The neuron either fires completely or not at all; the intensity of the signal is determined by the frequency of action potentials, not their size.

Electrochemical Communication

Neurons communicate with each other through a combination of electrical and chemical processes.

• Electrical Signal: The action potential travels down the axon.

• Chemical Signal: When the action potential reaches the axon terminal, it triggers the release of neurotransmitters into the synapse.

• Neurotransmitters: Chemical messengers that bind to receptors on the receiving neuron's dendrites, transmitting the signal.

• Types of Messages:

  • Excitatory: Increase the likelihood that the receiving neuron will fire.

  • Inhibitory: Decrease the likelihood that the receiving neuron will fire.

Summary Table: Key Neural Components

Component	Function
Cell Body (Soma)	Contains nucleus, builds cell components
Dendrites	Receive information
Axon	Transmits information
Axon Terminal	Releases neurotransmitters
Glial Cells	Support, protect, insulate neurons
Myelin	Insulates axons, speeds transmission

Key Equations

• Resting Potential: $V_{rest} \approx -70\,\text{mV}$

• Action Potential: $V_{peak} \approx +40\,\text{mV}$

Example: Multiple Sclerosis

In MS, the immune system attacks myelin, leading to disrupted neural communication and symptoms such as muscle weakness and coordination problems.

Additional info:

• Neural communication is foundational for all psychological processes, including sensation, perception, movement, and cognition.

• Glial cells are increasingly recognized for their role in psychological disorders and brain health.