Deck 4: Excitability and Chemical Signaling in Nerve Cells

Question 1

Assume that you are able to monitor the rate of firing of a single neuron.Assume that you apply a drug that acts as an agonist at the neuron's autoreceptors located on its cell body.Indicate what the most likely effect the drug would have on the neuron's firing rate and provide a reasonable explanation for the mechanism underlying this effect.

Answer 1

Activation of the autoreceptors would likely hyperpolarize the somatic membrane (e.g., enhancing K⁺ flow out of the neuron), making the neuron less excitable and decrease its firing rate.

Question 2

The opening of "voltage sensitive" sodium (Na+) channels at a neuron's axon hillock results in

A)an action potential
B)a refractory period
C)an inhibitory postsynaptic potential
D)an excitatory postsynaptic potential

Answer 2

A

Question 3

An action potential refers to

A)an exchange of positive and negative ions across the axon membrane
B)the release of chemicals into the synapse
C)the stimulation of dendrites
D)positive ions flowing out of the neuron

Answer 3

A

Question 4

What are two basic functional distinctions between synaptic neurotransmission and nonsynaptic diffusion neurotransmission (volume transmission) in the brain?

Question 5

The chemicals that are released by axons into a synapse to alter the excitability of other neurons are called

A)ions
B)neurotransmitters
C)synaptic vesicles
D)enzymes

Question 6

What is a synapse?

A)the connection between one node and the next
B)the connection between the glia and a neuron
C)the junction between an axon terminal and another neuron
D)the area between a neuron's cell body and its axon

Question 7

A major difference between a cell axon and a cell dendrite is that a dendrite

A)is longer and thicker
B)conducts information toward the cell body
C)is encased in a myelin sheath
D)conducts information away from the cell body

Question 8

Hyperpolarization of the dendritic membrane through the actions of a neurotransmitter is referred to as

A)an inhibitory postsynaptic potential
B)an excitatory postsynaptic potential
C)an action potential
D)the refractory period

Question 9

Drugs that affect mood, behavior, and perception most commonly act by

A)altering the normal biochemical functions carried out at the synapse
B)increasing the excitability of neurons
C)decreasing the excitability of neurons
D)slowing the action potential down

Question 10

A sudden change in electrical potential of a neuron membrane which travels along the neuron axon is called

A)a resting potential
B)an action potential
C)hyperpolarization
D)none of these

Question 11

After a neurotransmitter is released from an axon terminal, what are three things that can happen to it?

Question 12

"Information" typically enters a neuron through the

A)axon
B)dendrites
C)mitochondria
D)autoreceptors

Question 13

An action potential arrives at an axon terminal.Describe the general process of synaptic neurotransmission from that point on with respect to presynaptic and postsynaptic activity in the synapse.

Question 14

Under baseline conditions, each neuron is said to be _____________.

A)charged
B)polarized
C)ready
D)volatized

Question 15

The normal sequence of conduction of information through a single neuron is as follows:

A)axon terminal, axon, cell body, dendrite
B)cell body, axon, dendrite, axon terminal
C)dendrite, cell body, axon terminal, axon
D)dendrite, cell body, axon, axon terminal

Question 16

What does "retrograde neurotransmission" refer to?
e.g., GABA and glutamate, from presynaptic neurons.
Multiple choice questions.

Question 17

Assume that we activate a neuron's autoreceptors that are located on its presynaptic terminals.What are two things that are most likely going to happen regarding the neurotransmitters of that neuron?

Question 18

In terms of an individual neuron's excitability, what would be the consequence of a drug that reduced the ability of voltage sensitive sodium ion channels at a neuron's axon hillock open up?

Question 19

The predominant action of a neuron in the central nervous system is to

A)stimulate (excite) other neurons
B)inhibit the firing of other neurons
C)either increase or decrease the excitability of other neurons and thus alter their tendency to fire
D)alter metabolic activities which take place in the nucleus of other neurons

Question 20

What does depolarization in a neuron refer to?

Question 21

Cocaine's local anesthetic properties are most likely due to its ability to

A)occupy Na⁺ channels and block Na⁺ flow into axons
B)block neurotransmitter receptors
C)facilitate the release of inhibitory neurotransmitters
D)reduce the release of excitatory neurotransmitters

Question 22

If one measures the voltage potential of a presynaptic neuron and a postsynaptic neuron that form a synapse, the magnitude of the potential measured at the postsynaptic membrane is typically ______________________ the potential measured at the presynaptic membrane when an action potential arrives at the presynaptic neuron's axon terminal.

A)larger than
B)smaller than
C)equal to

Question 23

The processes influencing the shift in threshold potential which initiates an action potential most commonly involve (1) ; the processes leading to the propagation of an action potential along an axon involve (2)

A)(1) voltage gated ion channels; (2) chemically gated ion channels
B)(1) chemically gated ion channels; (2) voltage gated ion channels
C)(1) chemically gated ion channels; (2) chemically gated ion channels
D)(1) voltage gated ion channels; (2) voltage gated ion channels

Question 24

A force through which the resting potential of neurons is maintained involves

A)ion concentration gradient pressure
B)electrostatic pressure
C)sodium-potassium pumps in neuronal membranes
D)all of these

Question 25

During an action potential, which of the following events occur?

A)Na+ (sodium ions) flows into neuron, followed by K+ (potassium ions) flowing out of the neuron
B)Na+ flows out of neuron, followed by K+ flowing into the neuron
C)K+ flows into neuron, followed by Na+ flowing out of the neuron
D)K+ flows out of neuron, followed by Na+ flowing into the neuron

Question 26

Which type of receptors appear to exert primarily inhibitory feedback actions on neurons?

A)ionotropic receptors
B)postsynaptic receptors
C)autoreceptors
D)heteroreceptors

Question 27

An inhibitory postsynaptic potential can be the result of

A)chloride ions (Cl^-) entering the somatodendritic regions of a postsynaptic neuron
B)potassium ions (K⁺) exiting the somatodendritic regions of a postsynaptic neuron
C)either of these
D)neither of these Chapter 4.Answers to multiple choice questions and

Question 28

When chemically (ligand) gated channels open and allow negatively charged ions (e.g., chloride, Cl^-) to enter a neuron in the dendrites or cell body, the consequence is

A)a decrease in the neuron's excitability (i.e., its tendency to create an action potential)
B)an increase in the neuron's excitability (i.e., its tendency to create an action potential)
C)to create an action potential

Question 29

In the human brain, the transmission of a stimulus along a neuron is electrical and its transmission between neurons is predominantly

A)electromagnetic
B)tactile
C)chemical
D)also electrical

Question 30

The voltage potential of an individual neuron at rest is approximately

A)30 mV
B)70 mV
C)-10 mV
D)-70 mV

Question 31

The magnitude of an action potential _____________________as it moves down the axon from the axon hillock to the axon terminal.

A)increases
B)decreases
C)is unchanged
D)varies erratically