The voltage at a receptor site has just changed from -70 millivolts to -75 millivolts as a result of an _______ and will ________.
a). inhibitory postsynaptic potential;increase the likelihood of an action potential.
b). excitatory postsynaptic potential;decrease the likelihood of an action potential.
c).nhibitory postsynaptic potential;decrease the likelihood of an action potential.
The resting potential is increased, and the change must be to positive to promote an action potential. With this info, what would you pick?
The correct answer is c) inhibitory postsynaptic potential; decrease the likelihood of an action potential.
To understand why, let's break down the question:
1. The voltage at a receptor site has changed from -70 millivolts to -75 millivolts: This means there has been a change in the membrane potential of the neuron at the receptor site.
2. As a result of an inhibitory postsynaptic potential: An inhibitory postsynaptic potential (IPSP) is a type of electrical potential that occurs when neurotransmitters released by a presynaptic neuron bind to receptors on the postsynaptic neuron. The binding of these neurotransmitters generally leads to an inhibitory effect on the postsynaptic neuron, making it less likely to generate an action potential.
3. The change in voltage from -70 millivolts to -75 millivolts caused by the IPSP will: When the membrane potential becomes more negative (in this case, from -70 mV to -75 mV), it moves further away from the threshold required to trigger an action potential. This decrease in voltage makes it less likely for an action potential to occur, as it requires the membrane potential to reach a certain threshold level (typically around -55 millivolts). Hence, the likelihood of an action potential is decreased.
So, in summary, when the voltage at a receptor site changes due to an inhibitory postsynaptic potential, such as in this case, from -70 millivolts to -75 millivolts, it decreases the likelihood of an action potential.
The correct answer is:
c) inhibitory postsynaptic potential; decrease the likelihood of an action potential.
Explanation:
Inhibitory postsynaptic potentials (IPSPs) occur when the voltage at a receptor site becomes more negative or hyperpolarized. In this case, with the voltage changing from -70 millivolts to -75 millivolts, it indicates that the receptor site has become more negative, which is characteristic of an IPSP. IPSPs tend to decrease the likelihood of an action potential by making the cell more resistant to depolarization and therefore reducing the chances of the voltage reaching the threshold for an action potential to occur.