Neurotransmitter

Definition

A neurotransmitter is a chemical messenger that transmits signals across a synapse from one neuron to another, facilitating communication within the nervous system. These molecules play a critical role in various physiological functions, including mood regulation, muscle contraction, and cognitive processes. By binding to specific receptors on the target neuron, neurotransmitters can initiate or inhibit electrical impulses, influencing how the brain and body respond to stimuli.

5 Must Know Facts For Your Next Test

1. There are over 100 different types of neurotransmitters, each with specific roles and effects in the nervous system.
2. Some common neurotransmitters include serotonin, dopamine, acetylcholine, and norepinephrine, which influence emotions, movement, and attention.
3. Neurotransmitters can be excitatory or inhibitory; excitatory neurotransmitters increase the likelihood of an action potential in the receiving neuron, while inhibitory neurotransmitters decrease that likelihood.
4. The balance of neurotransmitters is crucial for mental health; an imbalance can lead to conditions like depression, anxiety, and schizophrenia.
5. Neurotransmitter action is typically brief, as they are quickly removed from the synaptic cleft by reuptake into the presynaptic neuron or broken down by enzymes.

Review Questions

• How do neurotransmitters influence neuronal communication at the synapse?
  • Neurotransmitters are essential for communication between neurons at the synapse. When an action potential reaches the end of a neuron, it triggers the release of neurotransmitters into the synaptic cleft. These chemicals then bind to receptors on the postsynaptic neuron, leading to either excitation or inhibition of that neuron. This process allows for rapid signaling throughout the nervous system and is fundamental for everything from reflexes to complex behaviors.
• Compare and contrast excitatory and inhibitory neurotransmitters in terms of their effects on neuronal activity.
  • Excitatory neurotransmitters promote neuronal firing by depolarizing the postsynaptic membrane, making it more likely for an action potential to occur. In contrast, inhibitory neurotransmitters hyperpolarize the membrane, reducing the chance of an action potential. Both types are crucial for maintaining balance in neural circuits; too much excitation can lead to seizures, while excessive inhibition can cause sedation or depression. Understanding these differences helps elucidate how various drugs and medications can affect mood and behavior.
• Evaluate how alterations in neurotransmitter levels can impact overall neurological function and behavior.
  • Alterations in neurotransmitter levels can significantly affect neurological function and behavior. For instance, decreased levels of serotonin are associated with depression and anxiety disorders, while imbalances in dopamine are linked to conditions such as schizophrenia and Parkinson's disease. The intricate balance of these chemicals is vital for maintaining mental health; therefore, treatments often focus on restoring this balance through medications that either increase or stabilize neurotransmitter levels. Understanding these dynamics is essential for developing effective therapies for various mental health issues.

Related terms

synapse: The junction between two neurons where neurotransmitters are released and received, allowing communication between nerve cells.

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

action potential: An electrical impulse that travels along the axon of a neuron, initiated when a neurotransmitter binds to its receptor and depolarizes the cell membrane.