Psychology Nervous System:

Overview of the Nervous System

• The nervous system operates as a communication network, constantly receiving, integrating, and transmitting signals.

• It manages information similar to how the circulatory system manages blood.

Structure of the Nervous System

• Peripheral Nervous System (PNS): Comprises nerves outside the brain and spinal cord.

  • Divided into two main parts:

    • Somatic Nervous System: Associated with voluntary control of body movements.

• Central Nervous System (CNS): Includes the brain and spinal cord.

Types of Cells in the Nervous System

• Neurons: The primary cells responsible for transmitting signals.

• Glial Cells: Supportive cells that assist neurons by:

  • Supplying nutrients.

  • Removing waste.

  • Come in various forms and perform different functions.

Neuron Structure and Function

• Dendrites:

  • Branch-like structures (dendritic trees).

  • Specialized to receive information from other neurons.

• Axons:

  • Conduct impulses away from the neuron's cell body.

  • Many axons are insulated by a myelin sheath, a fatty substance that:

    • Speeds up signal transmission.

• Synapses:

  • Junctions where information is passed from a neuron to another cell.

  • Presynaptic Neuron: sends the signal.

  • Postsynaptic Neuron: receives the signal.

Electrical Activity in Neurons

• Neurons can be in a resting state when not conducting impulses.

  • The neuron is polarized:

    • Negatively charged inside.

    • Positively charged outside.

• Action Potential: A brief electrical change in a neuron's charge, generated when stimulated.

  • Involves:

    • Opening of potassium gates initially.

    • Sodium gates opening in sequence along the axon, propagating the impulse.

  • Absolute Refractory Period: The minimum time after an action potential during which another action potential cannot occur.

• All or None Law: Neurons either fire or they do not. They convey stimulus strength through the frequency of firing.

Neurotransmitters and Synaptic Transmission

• Neurotransmitters: Chemicals released by terminal buttons at synapses that act as messengers to activate neighboring cells.

• Synaptic Cleft: The gap between neurons that neurotransmitters must cross for communication.

• Serious depression can be associated with abnormally low activity at norepinephrine synapses.