Neurotransmitters

Definition

Neurotransmitters are chemical messengers that transmit signals across synapses from one neuron to another, playing a crucial role in the communication within the nervous system. They help regulate various physiological processes, including mood, sleep, and movement, by binding to specific receptors on the postsynaptic neuron. The balance and function of neurotransmitters are essential for normal brain function and can influence behavior and bodily functions.

5 Must Know Facts For Your Next Test

1. Neurotransmitters can be categorized into excitatory neurotransmitters, which increase the likelihood of a neuron firing an action potential, and inhibitory neurotransmitters, which decrease that likelihood.
2. Some common neurotransmitters include serotonin, dopamine, acetylcholine, and gamma-aminobutyric acid (GABA), each playing unique roles in brain function.
3. Neurotransmitter release is often triggered by an influx of calcium ions into the presynaptic neuron following an action potential.
4. The reuptake of neurotransmitters back into the presynaptic neuron is a key mechanism that regulates their availability and action in the synaptic cleft.
5. Disruptions in neurotransmitter systems can lead to various neurological and psychiatric disorders, including depression, anxiety, and schizophrenia.

Review Questions

• How do neurotransmitters influence neuronal communication and what mechanisms are involved in their release?
  • Neurotransmitters facilitate neuronal communication by transmitting signals across synapses. When an action potential reaches the axon terminal, it triggers calcium ions to enter the presynaptic neuron. This influx prompts vesicles filled with neurotransmitters to fuse with the membrane and release their contents into the synaptic cleft. The neurotransmitters then bind to receptors on the postsynaptic neuron, leading to either excitation or inhibition of that neuron.
• Compare and contrast excitatory and inhibitory neurotransmitters in terms of their roles in synaptic transmission.
  • Excitatory neurotransmitters promote the firing of action potentials in neurons by depolarizing the postsynaptic membrane. In contrast, inhibitory neurotransmitters hyperpolarize the postsynaptic membrane, making it less likely for an action potential to occur. This balance between excitatory and inhibitory signals is crucial for maintaining proper neuronal function and ensuring effective communication within neural circuits.
• Evaluate the impact of imbalances in neurotransmitter systems on mental health disorders and provide examples.
  • Imbalances in neurotransmitter systems can significantly impact mental health disorders. For instance, low levels of serotonin are often associated with depression, while excessive dopamine activity may contribute to symptoms of schizophrenia. Understanding these relationships allows for targeted treatments such as selective serotonin reuptake inhibitors (SSRIs) for depression or antipsychotic medications for schizophrenia. This evaluation underscores the importance of neurotransmitter balance in overall mental well-being.

Related terms

synapse: The junction between two neurons where neurotransmitters are released and received, allowing for communication in the nervous system.

receptors: Proteins on the surface of neurons that bind to neurotransmitters, initiating a response in the postsynaptic cell.

action potential: A temporary reversal of the electrical charge across a neuron's membrane that propagates along the axon, ultimately leading to the release of neurotransmitters.