Neurotransmitter

Definition

A neurotransmitter is a chemical messenger that transmits signals across synapses from one neuron to another or to other types of cells. These molecules play a critical role in communication within the nervous system, influencing a range of functions from muscle contraction to mood regulation.

5 Must Know Facts For Your Next Test

1. Neurotransmitters can be categorized into two main types: excitatory and inhibitory, affecting whether a neuron is more likely or less likely to fire an action potential.
2. Common neurotransmitters include serotonin, dopamine, acetylcholine, and norepinephrine, each playing distinct roles in the body.
3. Neurotransmitter release occurs when an action potential reaches the axon terminals, leading to calcium ion influx and subsequent fusion of vesicles containing neurotransmitters with the presynaptic membrane.
4. After transmitting signals, neurotransmitters can be broken down by enzymes, reabsorbed by the presynaptic neuron in a process called reuptake, or diffuse away from the synapse.
5. Dysfunction in neurotransmitter systems has been linked to various neurological and psychiatric disorders, including depression, anxiety, and schizophrenia.

Review Questions

• How do neurotransmitters influence neuronal communication at the synapse?
  • Neurotransmitters are released from the presynaptic neuron into the synapse where they bind to specific receptors on the postsynaptic neuron. This binding can either stimulate or inhibit the generation of an action potential in the postsynaptic neuron, thereby influencing its activity. The balance between excitatory and inhibitory neurotransmitter effects determines how effectively information is transmitted through neural circuits.
• What roles do different types of neurotransmitters play in regulating body functions?
  • Different neurotransmitters serve various functions throughout the body. For instance, dopamine is crucial for reward and pleasure pathways, while serotonin regulates mood and emotional responses. Acetylcholine is essential for muscle contraction and plays a role in memory and learning. The intricate balance and interaction between these neurotransmitters are vital for maintaining homeostasis and overall mental and physical health.
• Evaluate how disruptions in neurotransmitter systems can impact mental health disorders.
  • Disruptions in neurotransmitter systems can lead to significant mental health disorders by altering normal signaling pathways. For example, a deficiency in serotonin is commonly associated with depression, whereas an imbalance of dopamine levels may contribute to conditions like schizophrenia. These disturbances can create a cascade of effects that impact mood, cognition, and behavior, highlighting the importance of neurotransmitters in both neurological function and psychological well-being.

Related terms

Synapse: The junction between two neurons, where neurotransmitters are released to transmit signals.

Receptor: A protein molecule on the surface of a cell that binds to specific neurotransmitters, triggering a response in the cell.

Action Potential: A rapid electrical signal that travels along the axon of a neuron, initiated by the influx of ions when neurotransmitters bind to receptors.