Question 1

The neurons in Noor's arm just sent a neural impulse. It will be 1-2 milliseconds before another neural impulse can be generated. What do we call this brief time increment, when another neural impulse cannot occur?

Accepted Answer

The brief time increment when another neural impulse cannot occur is called the absolute refractory period. During this time, the neuron is still recovering from the previous impulse and cannot generate a new one.

Question 2

Peggy smells a very strong odour; Harry smells an odour that is barely detectable. Based on what is known about neural transmission, what should we predict about each of their action potentials?

Accepted Answer

The all-or-none principle states that action potentials are the same size regardless of stimulus intensity. The difference in perception is due to the frequency of action potentials, not their size.

Question 3

Tracey became dehydrated during a recent illness, and the levels of sodium in her body were significantly reduced. What would we expect to occur if enough sodium was lost?

Accepted Answer

Sodium plays a critical role in the action potentials that occur in the nervous system. When sodium levels are low, there is not enough of it to enter the neuron and trigger an action potential. As a result, there would be fewer action potentials occurring in the nervous system. Option A is incorrect because low sodium levels would cause a decrease in action potentials, not an increase. Option B is incorrect because sodium does not play a role in the production of neurotransmitters, and Option D is incorrect because glial cells are not directly affected by low sodium levels.

Question 4

Which of the following is the correct sequence of steps through which neurotransmitters progress during synaptic transmission?

Accepted Answer

The correct sequence of steps during synaptic transmission is synthesis, release, binding, inactivation, and reuptake. This is because neurotransmitters are synthesized in the presynaptic neuron, then released into the synaptic cleft, where they bind to receptors on the postsynaptic neuron. After binding, the neurotransmitters are inactivated or broken down, and any excess neurotransmitters are taken back up into the presynaptic neuron through reuptake. Choice B correctly follows this sequence.

Question 5

What happens when a neurotransmitter is released, but it does not fit into a suitable receptor channel on the postsynaptic neuron?

Accepted Answer

If a neurotransmitter is released but does not fit into a suitable receptor channel on the postsynaptic neuron, it will not have any effect on the firing potential of the postsynaptic neuron. This is because neurotransmitters can only have an effect if they are able to bind to a receptor on the postsynaptic cell, causing a change in the membrane potential. If the neurotransmitter does not fit into a suitable receptor, it will not be able to cause this change and the firing potential of the postsynaptic neuron will not be affected.

Question 6

If a brain has several synapses that are not particularly active, and those synapses are eliminated, what does this reflect?

Accepted Answer

The elimination of synapses that are not particularly active is part of the process of synaptic pruning, where unnecessary synapses are eliminated in order to increase the efficiency of neural networks. This process is important for neural development and learning.

Question 7

Where are neurotransmitters stored?

Accepted Answer

Neurotransmitters are stored in the synaptic vesicles, which are located in the presynaptic terminal of a neuron. When an action potential reaches the terminal, these vesicles release the neurotransmitters into the synaptic cleft, where they bind to receptors on the postsynaptic neuron.

Question 8

The voltage at a receptor site has just changed from -70 millivolts to -75 millivolts. What caused the change?

Accepted Answer

An inhibitory postsynaptic potential (IPSP) would cause hyperpolarization and a decrease in voltage, such as changing from -70 mV to -75 mV.

Question 9

What is an action potential?

Accepted Answer

An action potential is an electrical signal that travels along the axon of a neuron. This signal is generated when the neuron receives enough stimulation to reach its threshold for firing. Once the threshold is reached, a series of ion channels open and close, allowing positively charged ions to enter the cell and then causing a rapid depolarization and repolarization of the membrane potential. This wave of depolarization travels down the axon of the neuron, allowing it to communicate with other neurons or cells.

Question 10

What is a good analogy for the way in which a neurotransmitter binds to receptor sites?

Accepted Answer

A neurotransmitter binding to receptor sites is like a key fitting in a lock because the shape of the neurotransmitter molecule and the receptor site are specific and complementary, much like a key and a lock. This allows the neurotransmitter to unlock the receptor and activate or inhibit the cell's response.

Question 11

Which of the following is known about action potentials?

Accepted Answer

Action potentials are generated in an all-or-none fashion, meaning that once the threshold of excitation is reached, they will fire at full strength regardless of the intensity of the incoming stimulation. This is a fundamental characteristic of neural communication. Choices A, B, and D are incorrect as they do not accurately reflect the nature of action potentials.

Question 12

What do we call the space between a terminal button and a dendrite?

Accepted Answer

The space between a terminal button and a dendrite is called the synaptic cleft. It is the small gap that separates the two neurons at a synapse where neurotransmitters are released and received by the dendrites of the postsynaptic neuron. Option A and D are incorrect because a transmission gap refers to a delay in the conduction of neural signals across axons, and neuromodulators are a type of neurotransmitter that modulate the activity of other neurotransmitters. Option B is incorrect because the midsynaptic potential range is not a term commonly used in neuroscience.

Question 13

Sara is holding Scott's hand during a scary movie. Suddenly she squeezes his hand very hard. When she does this, what will the nerves in Scott's hand do?

Accepted Answer

When Sara squeezes Scott's hand very hard, the nerves in his hand will start to fire at a faster rate. This is because the increased pressure on the nerve cells will depolarize them, leading to the opening of voltage-gated ion channels and the propagation of an action potential down the axon. As a result, the nerve cells will fire more frequently and send stronger signals to Scott's central nervous system.

Question 14

Fiona puts her hands into a sinkful of lukewarm water; Luke puts his hands into a sinkful of ice-cold water. What should we predict about each of their action potentials?

Accepted Answer

The all-or-none principle states that action potentials are always the same size and strength regardless of the stimulus intensity, as long as the threshold is reached.

Question 15

What is the term for the minimum length of time between action potentials?

Accepted Answer

The term for the minimum length of time between action potentials is the absolute refractory period. This is the period following an action potential where the neuron is unable to fire another action potential, regardless of the strength or duration of the stimulus.

Question 16

The voltage at a receptor site has just changed from -70 millivolts to -67 millivolts. What will this lead to?

Accepted Answer

The change in voltage from -70 millivolts to -67 millivolts indicates a depolarization of the cell, which would increase the likelihood of an action potential.

Question 17

What type of electric potential increases the likelihood that the postsynaptic neuron will fire?

Accepted Answer

An excitatory postsynaptic potential (EPSP) is a type of electric potential that increases the likelihood that the postsynaptic neuron will fire. This occurs when positively charged ions enter the postsynaptic neuron, reducing the membrane potential and making it more likely to reach the threshold for an action potential. All-or-none potentials refer to the nature of action potentials themselves and not the postsynaptic potential. Inhibitory postsynaptic potentials (IPSPs) decrease the likelihood of the postsynaptic neuron firing, while excitatory presynaptic potentials are not a type of electric potential associated with the postsynaptic neuron firing.

Question 18

What is the typical speed of an action potential?

Accepted Answer

The typical speed of an action potential is up to 300 kilometres/hour.

Question 19

What do we call the process of reabsorption of neurotransmitters into the presynaptic neuron?

Accepted Answer

The process of reabsorption of neurotransmitters into the presynaptic neuron is called reuptake. This is an essential process for regulating the levels of neurotransmitters in the synapse and maintaining proper neural function. Reuptake is carried out by specific transporter proteins on the presynaptic neuron and can also be targeted by certain medications, such as selective serotonin reuptake inhibitors (SSRIs), to treat depression and other mental health disorders. Choices B, C, and D are not accurate terms for this process.

Question 20

What do synaptic vesicles do?

Accepted Answer

Synaptic vesicles are sacs within the axon terminal of a neuron that store and release neurotransmitters, which are chemical messengers that allow for communication between neurons. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect as they do not accurately describe the function of synaptic vesicles.

Quiz 3: A:The Biological Bases of Behaviour