Biological Psychology: Central Nervous System and Neurones

Neurone Structure

• Cell Body: Contains the nucleus with the cell's genetic material.
• Dendrites: Receive signals from other neurones or sensory receptor cells.
• Axon: Carries nerve impulses (action potential) away from the cell body to axon terminals.
• Myelin Sheath: Insulates the axon (except in relay neurones) to speed up electrical impulses.
• Nodes of Ranvier: Gaps in the myelin sheath that facilitate faster electrical transmission through saltatory conduction.
• Axon Terminal: Connects the neurone to other neurones or organs via synaptic transmission.

Key Terms

• Nucleus: Control center of the cell, containing chromosomal DNA.
• Dendrite: Receives nerve impulses from adjacent neurones.
• Axon: Electrical signals pass along it.
• Myelin Sheath: Insulates the axon.
• Nodes of Ranvier: Speed up impulse transmission by forcing it to 'jump'.
• Terminal Buttons: Send signals to adjacent cells.

Saltatory Conduction

Saltatory conduction is the process where action potentials jump along myelinated axons from one node of Ranvier to the next, increasing the speed of electrical transmission.

Types of Neurones

• Sensory Neurones: Carry impulses from receptor cells to the spinal cord and brain (PNS to CNS).
• Relay Neurones: Found in the brain and spinal cord, connecting sensory and motor neurones (CNS to CNS).
• Motor Neurones: Found in the CNS, controlling muscle movements by releasing neurotransmitters.

Synapses

• Excitatory Synapse: Increases activity of the post-synaptic membrane via influx of Na+ ions (EPSP).
• Inhibitory Synapse: Decreases activity of the post-synaptic membrane via influx of Cl- ions (IPSP).