When a sensory neuron receives a stimulus that brings it to...

When a sensory neuron receives a stimulus that brings it to threshold, it will do all of the following EXCEPT: (A) $\quad$ become depolarized. (B) $\quad$ transduce the stimulus to an action potential. (C)$\quad$ inhibit the spread of the action potential to other sensory neurons. (D) $\quad$ cause the release of neurotransmitters onto cells in the central nervous system.

When a sensory neuron receives a stimulus that brings it to threshold, it will do all of the following EXCEPT:
(A) $\quad$ become depolarized.
(B) $\quad$ transduce the stimulus to an action potential.
(C)$\quad$ inhibit the spread of the action potential to other sensory neurons.
(D) $\quad$ cause the release of neurotransmitters onto cells in the central nervous system.

Key Concepts

Sensory Transduction

Sensory transduction is the conversion of a specific form of external stimulus, such as light, sound, or touch, into an electrical signal in a sensory neuron. This process allows the nervous system to interpret and respond to environmental changes.

Depolarization

Depolarization is the process where a neuron's membrane potential becomes less negative, typically due to the influx of positive ions such as sodium. This change in membrane potential is essential for initiating the sequence of events that leads to an action potential.

Action Potential Generation

An action potential is an all-or-none electrical signal that rapidly propagates along the axon after the membrane potential reaches a critical threshold. This event is crucial for transmitting information within the nervous system.

Neurotransmitter Release

Neurotransmitter release involves the exocytosis of chemical messengers from the presynaptic terminal of a neuron into the synaptic cleft, where they bind to receptors on adjacent neurons. This is a fundamental mechanism for communication between neurons in the central nervous system.

Transcript

00:01 This question asks, when a sensory neuron receives a stimulus that brings it to threshold, it will do all of the following except a, become depolarized, b, transdues the stimulus to an action potential, c, inhibit the spread of the action potential to the other sensory neurons, or d, causes a release of neurotransmitters onto cells in the central nervous system.

00:25 So if we are trying to locate the incorrect statement, right, we have to look at each statement evaluated, determine if it's true or false.

00:33 They become depolarized, right? this is true, because when we have a stimulus that is going to reach the threshold of the action potential, so the neuron is going to fire due to the stimulus being present, the way the neuron fires, it becomes depolarized, meaning that the resting membrane potential, which could be somewhere around negative 55 millivolts or so, right? this resting membrane potential, if we're looking at a graph, is going to shoot up, very high up.

01:09 And if we have zero right at this line, right, zero millivolts, and negative 55 being right down here, and with, let's say, 40 millivolts up here, right, we are going to find that this, as soon as the stimulus hits, we're going to dip down a little bit, and then boom, skyrocket all the way up to the maximum of our action potential.

01:41 This is going to be the depolarization phase, and we'll go over that in just a minute here.

01:45 And then we'll see that our polarity of the membrane is going to decrease after that, and then it will dip a little bit lower than the resting membrane potential, and then get back up to where it needs to be.

02:00 And then after that refractory period, it will be ready for firing once more.

02:05 So this right here is known as depolarization.

02:08 We have depolarized membrane, meaning that we have allowed for the ions to move along their respective concentration gradients.

02:18 So that is why we see this increase to zero from negative 55, and then this depolarization continues all the way up to 40.

02:31 And then we see a decrease back down as we polarize the membrane again using our sodium potassium pumps.

02:39 And that's how we get there...

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