Question 1

During the resting state of a voltage-gated Na⁺ channel,

Accepted Answer

The answer of During the resting state of a voltage-gated...

Question 2

Which type of axons has the largest diameter?

Accepted Answer

A fibers have the largest diameter among the three types of axons. They are myelinated and transmit signals fastest, making them responsible for conveying sensations of touch and motor control. B fibers are also myelinated, but are smaller in diameter and transmit signals slower than A fibers. C fibers are unmyelinated and have the smallest diameter, transmitting signals slowest among the three types of axons.

Question 3

Name the type of membrane channel that opens in response to touch, pressure, vibration, or tissue stretching and is found in the auditory receptors of the ear, and in touch and pressure receptors in the skin.

Accepted Answer

Mechanically gated channels open in response to physical force such as touch, pressure, vibration, or tissue stretching. They are found in auditory receptors of the ear and touch and pressure receptors in the skin.

Question 4

Name the type of membrane channel that opens in response to changes in membrane potential and is located in axons of all types of neurons.

Accepted Answer

Voltage-gated channels are the type of membrane channel that opens in response to changes in membrane potential and is located in axons of all types of neurons.

Question 5

When the summed total of postsynaptic potentials rises above threshold, creation of action potentials occurs

Accepted Answer

Action potentials are created at the trigger zone, which is the region where the axon hillock and initial segment of the axon come together. This is where the depolarization reaches threshold to initiate an action potential.

Question 6

Faster communication and synchronization are two advantages of

Accepted Answer

Electrical synapses allow for faster communication and synchronization because they allow direct flow of ions between cells, while chemical synapses require release and diffusion of neurotransmitters. Ligand-gated, voltage-gated, and mechanically-gated channels are types of ion channels found in both types of synapses but do not necessarily provide faster communication or synchronization.

Question 7

A postsynaptic neuron responds to neurotransmitters released by a presynaptic neuron by creating

Accepted Answer

A postsynaptic neuron can generate either excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs) in response to neurotransmitters, depending on the type of neurotransmitter and receptors involved.

Question 8

The nervous system can distinguish between a light touch and a heavier touch by

Accepted Answer

Changing the frequency of impulses sent to sensory centers allows the nervous system to distinguish between different types of touch. Light touch will generate a lower frequency of impulses than a heavy touch.

Question 9

IPSP stands for

Accepted Answer

IPSP stands for "inhibitory postsynaptic potential," which is a type of synaptic potential that makes it less likely for an action potential to be generated in the postsynaptic neuron. Choice A and D both include "presynaptic," which refers to events that occur before the synapse, whereas IPSPs occur after the synapse. Choice B includes "postsynaptic summation potential," but this is not a commonly used term in neuroscience.

Question 10

During this period, a second action potential can only be initiated by a larger than normal stimulus.

Accepted Answer

During the relative refractory period, a second action potential can be initiated, but it requires a larger than normal stimulus because the neuron is returning to its resting state.

Question 11

An excitatory neurotransmitter ___ the postsynaptic membrane.

Accepted Answer

Excitatory neurotransmitters, such as glutamate, bind to and open ion channels on the postsynaptic membrane, resulting in influx of positively charged ions (such as Na+), which leads to depolarization of the membrane potential. This depolarization can potentially trigger an action potential in the postsynaptic neuron.

Question 12

Name the type of membrane channel that randomly opens and closes and is found in dendrites, cell bodies, and axons of all types of neurons.

Accepted Answer

Leak channels are constantly open and allow ions to pass through them, thus contributing to the resting membrane potential. They are found in all types of neurons, including dendrites, cell bodies, and axons.

Question 13

Chromatolysis refers to

Accepted Answer

Chromatolysis refers to the breakdown or dispersion of Nissl bodies in the cytoplasm of a neuron, often after neural injury or under certain physiological conditions. Therefore, the best choice is D, "break up of Nissl bodies after neural injury." A is incorrect because it refers specifically to lysosomes, which are not necessarily involved in chromatolysis. B is incorrect because Wallerian degeneration refers to the degeneration of axons, not the breakdown of Nissl bodies. C is incorrect because although plasticity of neurons can involve changes in Nissl bodies, it does not necessarily involve their breakdown. E is incorrect because one of the choices must be correct.

Question 14

Which of the following terms is used to describe a type of synapse?

Accepted Answer

Axodendritic, axosomatic, and axoaxonic are all types of synapses, describing the connections between different parts of neurons.

Question 15

Name the type of membrane channel that opens in response to chemical binding and is found in dendrites of some sensory receptors like pain receptors, and in the dendrites and cell bodies of interneurons and motor neurons.

Accepted Answer

Ligand-gated channels open in response to chemical binding, allowing ions to flow through the membrane. They are found in dendrites of some sensory receptors like pain receptors, and in the dendrites and cell bodies of interneurons and motor neurons.

Question 16

Plasticity means:

Accepted Answer

Plasticity refers to the brain's ability to change, adapt and reorganize its structure and function based on experience, learning and development.

Question 17

Diffusion, enzymatic degradation, and uptake by cells are all ways to

Accepted Answer

Diffusion, enzymatic degradation, and uptake by cells are all ways to remove a neurotransmitter from the synaptic cleft. This allows for proper termination of a synaptic signal and prevents continuous stimulation of the postsynaptic cell. Choices B, C, D, and E are not correct as they do not relate to the mentioned mechanisms of neurotransmitter clearance.

Question 18

Saltatory conduction

Accepted Answer

Saltatory conduction is the process of rapid conduction of nerve impulses along myelinated axons. The myelin sheath insulates the axon and prevents ion leakage, so the flow of current is restricted to the nodes of Ranvier. Action potentials jump from node to node, which speeds up the transmission of the signal. Saltatory conduction does not occur in unmyelinated axons, and it does not selectively encode action potentials related to pain.

Question 19

Wallerian degeneration refers to

Accepted Answer

Wallerian degeneration refers to the degeneration of the distal end of axon and myelin sheath after neural injury. The proximal end undergoes chromatolysis, a series of changes in the neuronal body that results in the breakdown of Nissl bodies. This process is separate from Wallerian degeneration. Therefore, choice B is the best answer.

Question 20

This type of neural circuit consists of a single presynaptic neuron synapsing with several postsynaptic neurons.

Accepted Answer

A diverging circuit involves one presynaptic neuron connecting to multiple postsynaptic neurons, allowing the signal to be spread to various pathways.

Quiz 12: Introduction to the Nervous System

During the resting state of a voltage-gated Na+ channel,