Question 1

An afferent neuron

Accepted Answer

Afferent neurons carry sensory information from the peripheral parts of the body into the central nervous system (CNS), which includes the brain and spinal cord.

Question 2

The long cable like neurite that transmits information to other neurons is called a(n)

Accepted Answer

Axons are the long, slender projections of neurons that transmit electrical impulses away from the neuron's cell body (or soma) to other neurons, muscles, or glands, facilitating communication within the nervous system.

Question 3

The myelin sheath

Accepted Answer

The myelin sheath functions as an insulating layer around the axons of neurons, allowing electrical impulses to transmit quickly and efficiently along the nerve cells. This increases the speed of information transmission within the nervous system.

Question 4

During the resting potential

Accepted Answer

During the resting potential, the inside of the neuron's membrane is negatively charged compared to the outside, and the concentration of sodium ions (Na+) is indeed much greater outside the neuron than within it. This creates a difference in charge across the membrane, contributing to the neuron's ability to generate an action potential when stimulated. Choices A, C, and D describe conditions that are not characteristic of the resting potential.

Question 5

A nerve impulse (action potential) is caused initially by the

Accepted Answer

The initiation of a nerve impulse or action potential is primarily caused by the inward movement of sodium ions (Na+) into the neuron, which depolarizes the membrane.

Question 6

The refractory period, while brief, is a biologically significant phase of the signal transmission process because

Accepted Answer

The refractory period is crucial because it sets the limit on how frequently a neuron can fire, thereby determining its maximum firing rate. During the absolute refractory period, no stimulus can trigger another action potential, ensuring that each signal is distinct and preventing the neuron from being overstimulated. The relative refractory period allows a neuron to fire again, but only in response to a stronger-than-normal stimulus, not a weaker one, making option D correct. Options A and B inaccurately describe the effects of stimuli during the refractory periods, and while C might be a characteristic of the refractory period, it does not explain its biological significance in signal transmission.

Question 7

For many species, neurons fire only if they meet a certain threshold. In other words, these neurons do not emit a partial response. This describes the

Accepted Answer

The all-or-none phenomenon describes how neurons fire at full strength if a certain threshold is met, without partial responses, which matches the description given.

Question 8

The intensity of a stimulus, e.g., the difference between a dim light and a bright light, is coded

Accepted Answer

The intensity of a stimulus is coded both by the firing rate of neurons (how frequently a neuron fires) and by the number of neurons firing (with more neurons firing in response to a stronger stimulus). This combination allows the nervous system to accurately represent the intensity of stimuli.

Question 9

Occasionally one sees a fruit fly (Drosophila melanogaster) that shakes its legs, wings, or abdomen under ether anesthesia. This behavior is caused by a mutation that results in

Accepted Answer

The shaking behavior under ether anesthesia in fruit flies with this mutation is due to certain potassium channels not being formed, which disrupts the normal flow of potassium across the membrane. This affects the neuron's ability to send proper signals, leading to the observed involuntary movements.

Question 10

The area of the nervous system that determines whether the message of one neuron will generate an action potential in the next neuron is the

Accepted Answer

The synapse is the area of the nervous system where two neurons come close enough to pass messages from one to the next. It determines whether the message (neurotransmitter release) will generate an action potential in the receiving neuron, making it a critical site for neuronal communication.

Question 11

Although electrical synapses are much less common than chemical synapses, they are known for their speed of transmission and, thus, are most likely part of the neural circuitry that underlies

Accepted Answer

Escape behaviors often require rapid response times to avoid predators or dangerous situations. Electrical synapses facilitate this by allowing for quicker signal transmission compared to chemical synapses, making them ideal for the neural circuitry involved in initiating fast escape responses.

Question 12

Electrical synapses differ from chemical synapses in that electrical synapses

Accepted Answer

Electrical synapses allow for the direct flow of ions between neurons through gap junctions, which are essentially tiny tubes connecting the cytoplasm of adjacent neurons, enabling faster and more synchronized communication.

Question 13

The small storage sacs containing the neurotransmitter in the presynaptic neuron are called

Accepted Answer

Synaptic vesicles are small storage sacs within the presynaptic neuron that contain neurotransmitters, which are released into the synaptic cleft during synaptic transmission.

Question 14

When a neurotransmitter binds to the receptor on a postsynaptic neuron it may result in an EPSP which

Accepted Answer

An EPSP (Excitatory Postsynaptic Potential) depolarizes the membrane of the postsynaptic neuron, making it more likely to fire an action potential. This is achieved by the influx of positively charged ions, such as sodium (Na+), not by hyperpolarization or the specific ion movements described in options A and C.

Question 15

Breaking the neurotransmitter down with an enzyme so that its component parts can be absorbed for resynthesis, or molecules of the neurotransmitter being released intact from the postsynaptic cell so that it can absorbed and repackaged are ways to

Accepted Answer

These processes describe mechanisms for terminating or halting the effect of a neurotransmitter, not intensifying or prolonging its effect.

Question 16

Having received messages from hundreds or thousands of other neurons, a postsynaptic neuron will fire if

Accepted Answer

The firing of a postsynaptic neuron is determined by the net effect of all incoming signals. If the sum of excitatory and inhibitory inputs leads to sufficient depolarization, reaching the threshold, the neuron will fire an action potential. This process is known as the integration of synaptic inputs.

Question 17

Neuromodulators are chemicals that alter neuronal activity. Their effects are generally

Accepted Answer

The answer of Neuromodulators are chemicals that alter neuronal activity....

Question 18

Chemicals whose effects are mediated by substances within a postsynaptic neuron called second messengers, such as calcium or cAMP, are known as

Accepted Answer

Neuromodulators are chemicals that influence neural activity by affecting the postsynaptic neuron indirectly through the action of second messengers like calcium or cAMP, rather than by directly opening ion channels.

Question 19

When the neuromodulator protolin is administered to a male blue crab (Callinectes sapidus) at the same time that interneurons that trigger leg waving are being stimulated, the motor output assumes

Accepted Answer

Protolin, when administered alongside the stimulation of interneurons responsible for leg waving, enhances the motor output to produce the rhythmic leg waving seen in courtship displays of male blue crabs. This suggests that protolin plays a role in modulating behaviors associated with mating.

Question 20

It is the job of an animal's sensory system to

Accepted Answer

The primary function of an animal's sensory system is to be selective and transmit only biologically relevant stimuli. This ensures that the animal can respond to important environmental cues while ignoring irrelevant information, which is crucial for survival.

Quiz 6: Physiological Analysis-Nerve Cells and Behavior