Action Potentials: The Electrical Basis of Neural Communication

Action potentials are the electrochemical processes that generate impulses within neurons. This concept is fundamental to understanding how information is transmitted in the nervous system, a key focus of biological psychology.

Key aspects of action potentials include:

1. Resting potential: The state of a neuron when it is not producing an impulse but has the capacity to do so

2. Initiation of action potential:

   • Can be activated by a receptor cell
   • May receive an impulse from another neuron

3. Refractory period: The time during which the neuron is repolarizing and the sodium/potassium pump is active

Definition: The refractory period is the brief interval following an action potential during which a neuron cannot generate another impulse.

Highlight: The movement of sodium and potassium ions across the neuron's membrane creates an electrical current, which constitutes the impulse. This process is crucial for understanding how information is transmitted in the nervous system.

Example: When you touch a hot stove, sensory neurons in your fingertips generate action potentials that rapidly travel to your brain, resulting in the perception of heat and pain.

Understanding action potentials is essential for biological psychologists as it forms the basis of neural communication and influences all aspects of behavior and cognition.

The Neuron: Building Blocks of the Nervous System

Neurons are the fundamental units of the nervous system, playing crucial roles in generating and transferring impulses throughout the body. Biological psychologists study these cells extensively to understand the biological basis of human behaviour.

Key components of a neuron include:

1. Soma (cell body): Contains the nucleus and organelles
2. Dendrites: Receive impulses from other neurons or sensory organs
3. Axon: Transfers impulses to other neurons, muscles, or glands
4. Myelin sheath: Insulates the axon, ensuring rapid impulse transmission
5. Nodes of Ranvier: Gaps in the myelin sheath allowing chemical movement
6. Terminal buttons (axon terminals): Contain chemicals for impulse transmission

Vocabulary: The myelin sheath is an insulating layer of fat cells surrounding the axon, crucial for efficient impulse transmission.

Types of neurons include:

• Receptor cells: Detect environmental changes in sensory organs
• Sensory (afferent) neurons: Transfer impulses from receptor cells to the CNS
• Motor (efferent) neurons: Transfer impulses from the CNS to muscles or glands
• Interneurons: Transfer impulses between afferent and efferent neurons

Example: In a reflex action, such as quickly withdrawing your hand from a hot surface, sensory neurons detect the heat, interneurons process the information in the spinal cord, and motor neurons trigger muscle contraction to pull your hand away.