Neurotransmitter
A chemical messenger produced and stored in neurons. It is released into the synaptic gap by the presynaptic neuron and helps transmit signals between neurons by binding to receptors on the postsynaptic neuron.
Agonist
A substance that enhances or mimics the action of a neurotransmitter. It binds to the same receptors, amplifying the neurotransmitter’s effects.
Antagonist
A substance that inhibits the action of a neurotransmitter. It blocks or reduces neurotransmitter activity by binding to the receptors, dampening or stopping the signal.
Nicotine acts as an agonist for acetylcholine by stimulating its receptors. This activation increases neural signaling in the brain, leading to heightened focus, faster reaction times, and a sense of alertness or wakefulness.
Neurotransmission Process
Neurotransmission involves both electrical and chemical mechanisms.
- An electrical impulse travels along a neuron’s axon until it reaches the synapse.
- At the synapse, the process becomes chemical, causing neurotransmitters to release into the synaptic gap.
- These chemicals bind to receptors on the postsynaptic neuron, altering its electrical potential.
- The neurotransmitter can either be excitatory, promoting the continuation of the signal, or inhibitory, preventing the signal from progressing.
Neurons and Synapses
Neurons are the fundamental units of the nervous system, consisting of three main parts:
- Cell body: Contains the nucleus and essential cellular components.
- Dendrites: Receive signals from other neurons.
- Axon: Transmits signals away from the cell body to the synapse, where communication occurs.
- Synapses are the junctions where the axon of one neuron communicates with the dendrites of another.
Neurotransmitter Interaction: The activity of neurotransmitters can be modulated by various chemicals:
- Excitatory neurotransmitters: Increase the likelihood of the postsynaptic neuron firing an electrical impulse.
- Inhibitory neurotransmitters: Decrease the likelihood of the postsynaptic neuron firing.
Remember, Agonists and antagonists influence the strength or suppression of these signals.
ExampleGlutamate is an excitatory neurotransmitter, like pressing the "gas pedal" in a car. It increases brain activity, making the brain more alert and responsive. Higher glutamate levels make the brain more excitable, while lower levels slow things down.
GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter, like pressing the "brake pedal" in a car. It decreases brain activity, calming and relaxing the brain. Higher GABA levels promote calmness, while lower levels can lead to anxiety or overstimulation.
Key Neurotransmitters
Serotonin:
- Role: Regulation of mood, emotion, and aggression.
- Type: Inhibitory neurotransmitter.
- Example: Low serotonin levels have been linked to increased impulsivity and aggression.
Dopamine:
- Role: Associated with reward, motivation, and pleasure.
- Type: Can be both excitatory and inhibitory, depending on the receptor.
- Example: High dopamine activity in certain brain areas is linked to romantic attraction and addiction.
Acetylcholine:
- Role: Critical for learning, memory, and muscle control.
- Type: Excitatory neurotransmitter.
