Differences Between EPSP and Action Potential

EPSP vs Action Potential

Neuroscience has captivated the interest of many. It is a study on how the nervous system works and how the body is able to respond with different stimuli. The body itself contains chemicals which enable us to function and survive in this challenging environment. The brain is in command of the whole body and tells us what we need to do or how to react. It is the general of our body with its minions, the neurons. Neurons communicate with each other and send the messages to the general. With information at hand, the brain general can process new tactics on how to counter such feats. Most often, EPSP and action potential are involved in generating specific actions. The difference between EPSP and action potential will be elaborated upon in this article.

“EPSP” stands for “excitatory postsynaptic potential.” When there is a flow of positively charged ions towards the postsynaptic cell, a momentary depolarization of the postsynaptic membrane potential occurs. This phenomenon is known as EPSP. A postsynaptic potential becomes excitatory when the neuron is triggered to release an action potential. The EPSP is like the parent of the action potential since it is created when the neuron is triggered. There can be EPSP when there is a decrease in the outgoing positive ion charges. We call the trigger the excitatory postsynaptic current, or EPSC. EPSC is the flow of ions that causes EPSP.

In a single patch of postsynaptic membrane, multiple EPSPs can likely occur. EPSPs have an additive effect which means that the sum of all the individual EPSPs will result in a combined effect. Greater membrane depolarization takes effect when there are larger EPSPs created. The larger the EPSPs become, the more it reaches the limit of firing an action potential. The amino acid glutamate is the neurotransmitter associated with EPSPs. It is also the main neurotransmitter of the vertebrates’ central nervous system. Amino acid glutamate is then called the excitatory neurotransmitter.

Action potential is fired by EPSP. It is a momentary event wherein the cell’s electrical membrane potential instantly rises and falls. A consistent trajectory then follows. In neurons, action potentials are also called nerve impulses or spikes. A sequence of action potentials is called a spike train. Action potentials frequently occur in human cells since humans have neurons, endocrine cells, and muscle cells. When there is a signal, the neurons communicate with each other reaching EPSP until it needs to fire an action potential. Voltage-gated ion channels produce action potentials. These channels lie inside the plasma membrane of the cell. There is a phase called resting potential. When the membrane potential is nearing the resting phase, the voltage-gated ion channels are shut, but they immediately open when there is an increase in the membrane potential value. Sodium ions will flow when these channels open which further increases the membrane potential. As membrane potentials increase, more and more electric current flows. There are two basic types of action potentials in animal cells: voltage-gated sodium channels and voltage-gated calcium channels. Voltage-gated sodium channels last for about less than one millisecond while voltage-gated calcium channels last for about a hundred milliseconds or even longer.

Summary:

1. “EPSP” stands for “excitatory postsynaptic potential.”

2. Excitatory postsynaptic potential occurs when there is a flow of positively charged ions towards the postsynaptic cell, a momentary depolarization of postsynaptic membrane potential is created.

3. Action potentials are also called nerve impulses or spikes.

4. A postsynaptic potential becomes excitatory when the neuron is triggered to release an action potential.

5. Action potential is a momentary event wherein the cell’s electrical membrane potential instantly rises and falls.

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