Role of Neurotransmitters

Full Answer Section

1. Depolarization: When a neuron receives a stimulus, it causes the cell membrane to become more permeable to sodium ions. Sodium ions rush into the cell, making the inside more positive.
2. Rising Phase: As more sodium ions enter the cell, the membrane potential becomes even more positive. This positive feedback loop continues until the neuron reaches its action potential threshold.
3. Overshoot: The neuron's membrane potential continues to rise until it reaches its peak.
4. Repolarization: Potassium channels open, allowing potassium ions to flow out of the cell. This helps to restore the negative charge inside the cell.

1. www.numerade.com

1. Hyperpolarization: The membrane potential may briefly become more negative than the resting potential. This is known as hyperpolarization.
2. Refractory Period: The neuron is unable to fire another action potential for a short period of time. This helps to ensure that action potentials propagate in one direction.

The Role of Neurotransmitters

Action potentials travel along the length of a neuron's axon. At the end of the axon, the action potential triggers the release of neurotransmitters into the synaptic cleft, a small gap between the axon terminal of one neuron and the dendrites or cell body of another neuron.

Neurotransmitters bind to receptors on the postsynaptic neuron, causing changes in its membrane potential. These changes can either excite the postsynaptic neuron (making it more likely to fire an action potential) or inhibit it (making it less likely to fire).

The type of neurotransmitter released and the receptors it binds to determine whether the postsynaptic neuron will be excited or inhibited. This allows for complex patterns of neural activity and information processing in the brain.

Sample Answer

Neuronal Signaling: A Rapid Process

The Action Potential

Neurons communicate with each other through electrical signals known as action potentials. These signals are all-or-none events, meaning that they either occur in full or not at all. The process of an action potential is as follows:

1. Resting Potential: At rest, a neuron maintains a negative charge inside compared to the outside. This is due to the distribution of ions (sodium, potassium, chloride) across the cell membrane.