Neuron Structure and Function

Neuron Structure and Function

• A neuron is a nerve cell in the brain.
• The cell body contains the nucleus.
• Dendrites are branched structures that receive signals from other neurons.
• The axon is a long fiber that transmits signals to other neurons.
• Axon terminals, also known as synaptic sites, are the ends of axons that are close to other neurons.

Electrical Conduction in Neurons

• Positively charged sodium ions move through the neuronal membrane, causing a brief shift to a positive charge (depolarization).
• Potassium ions then exit the neuron through potassium channels, restoring the negative charge.

Myelination and Speed of Neuronal Transmission

• Myelin speeds up the transmission of action potentials along the axon.
• Myelination continues into adolescence.

Neuronal Firing

• Excitatory influences lower the threshold for firing a neuron, making it more likely to fire.
• Inhibitory influences raise the threshold, making it less likely to fire.

Major Neurotransmitters

• GABA (gamma-aminobutyric acid): An inhibitory neurotransmitter; linked to Huntington's disease.
• Acetylcholine (ACh): Involved in memory, muscle movement, and linked to Alzheimer's disease and convulsions.
• Serotonin: Associated with mood, sleep, and eating; implicated in depression and obsessive-compulsive disorder.
• Dopamine (DA): Related to voluntary movement, pleasure, and implicated in Parkinson's disease and schizophrenia.
• Endorphins: Act as neuromodulators and influence pain perception; can cause insensitivity or oversensitivity to pain.

Dopamine (DA) System Pathways

• Cell bodies for dopamine neurons are located in the substantia nigra (SN) and ventral tegmental area (VTA) of the midbrain.
• Dopamine neurons project along specific pathways:
  • Nigrostriatal pathway: Substantia nigra to the dorsal striatum.
  • Mesocortical pathway: Ventral tegmental area to the prefrontal cortex.
  • Mesolimbic pathway: Ventral tegmental area to the nucleus accumbens.

Explore the intricate world of neurons, the essential nerve cells that transmit signals in the brain. This quiz covers the structure of neurons, electrical conduction, myelination, and the mechanisms of neuronal firing. Test your understanding of how these components work together to facilitate communication in the nervous system.