Question 1

When the charge inside of a neuron shifts from -70 millivolts to +40 millivolts,it is called:

Accepted Answer

When the charge inside of a neuron shifts from -70 millivolts to +40 millivolts, it is called depolarization.

Question 2

What is the effect of the myelin sheath on the conduction of neural impulses?

Accepted Answer

The myelin sheath acts as an insulator and increases the speed of electrical conduction along the axon. This is because the myelin sheath prevents ion exchange through the cell membrane, forcing the action potential to "jump" from one node of Ranvier to the next, called saltatory conduction. As a result, the conduction of neural impulses is much quicker along myelinated axons compared to unmyelinated axons.

Question 3

In a large communication network such as the national telephone company,the actual cables and transmissions could be analogous to the body's neurons,while the technicians and mechanics who support the equipment are analogous to the body's _______.

Accepted Answer

Glial cells are support cells of the nervous system, performing functions such as providing nutrients to neurons and insulating them. The technicians and mechanics in the communication network also provide support and maintenance for the equipment.

Question 4

It is relatively easy to see how there can be millions of connections in the brain given the diverse structures of the _________________.

Accepted Answer

The axon and the dendrites are key structures in neurons that form numerous connections, allowing for complex neural networks in the brain.

Question 5

The function of the axon is to:

Accepted Answer

The axon is responsible for transmitting electrical messages from the cell body to other muscles, glands or neurons. It is the long, thin fiber that extends from the cell body and is covered in a myelin sheath, which speeds up the transmission of electrical impulses. The other options (A, B and C) describe functions of other parts of the neuron (the glial cells, the myelin sheath and the dendrites, respectively).

Question 6

When a neuron is stimulated,tiny protein structures on the cell membrane are activated and pump specific ions back and forth,thus changing the overall potential of the neuron.These cell membranes are called___________:

Accepted Answer

Ion channels are protein structures on the cell membrane that regulate the movement of ions such as sodium, potassium, and calcium in and out of the neuron. When a neuron is stimulated, these ion channels open and allow ions to move, which changes the overall potential of the neuron and generates an action potential.

Question 7

The presence of many branches on the axons makes it possible for a single neuron to connect to the dendrites of as many as 50,000 other neurons.The branches on the axons are called ___________:

Accepted Answer

The branches on the axons are called axon terminals, not cell bodies or dendrites. Glial cells are not branches on the axons.

Question 8

For a brief period of time,shortly after a neural impulse has been triggered,a neuron is not excitable and cannot fire another impulse.This is called ____________:.

Accepted Answer

The refractory period is the brief period of time during which a neuron cannot fire another impulse, immediately after a previous impulse has been triggered. Options A, B, and D refer to different stages of the neural impulse, but do not specifically describe the refractory period.

Question 9

The nervous system communicates the difference between a strong and weak stimulus by:

Accepted Answer

The nervous system communicates the difference between a strong and weak stimulus by varying the firing rate of the neuron. Strong stimuli will cause the neuron to fire more frequently, while weak stimuli will cause less frequent firing. This variation in firing rate allows the nervous system to differentiate between different levels of sensory input.

Question 10

The resting potential of a typical neuron is:

Accepted Answer

The resting potential of a typical neuron is approximately -70 millivolts. This means that the inside of the neuron is negatively charged relative to the outside, and this electrical gradient plays an important role in the transmission of signals within the nervous system. Option A is incorrect because -70 volts is an excessively large potential that would likely cause the neuron to explode, while option C is too small to generate meaningful electrical activity. Option D, 70 millivolts, is also incorrect because it implies a positive resting potential, which is not accurate.

Question 11

Scientists used to think that neurons communicated with each other through direct physical contact.With the advent of the electron microscope,the synapse or gap between neurons is evident and it is apparent that rather than direct contact,the communication continues through _______.

Accepted Answer

The synapse, or gap between neurons, is where neurotransmitters are released by the axon terminals of one neuron and taken up by the dendrites of another neuron. Therefore, the communication between neurons continues through neurotransmitters, not direct physical contact through axon terminals or dendrites or through action potentials.

Question 12

The resting potential of the typical neuron is determined by:

Accepted Answer

The resting potential of a typical neuron is around -70 mV, which is maintained by the distribution of ions across the neuron's membrane. There are more positive ions (such as Na+) outside the neuron and more negative ions (such as K+ and negatively charged proteins) inside. This creates a negative charge inside the neuron relative to the outside, leading to the resting potential.

Question 13

Branch-like fibres that collect messages from adjacent neurons and pass them along to the cell body of the receiving neuron are called _______________.

Accepted Answer

Dendrites are the branch-like fibres that collect messages from adjacent neurons and pass them along to the cell body of the receiving neuron. Axons are the long, slender projections of a neuron that conduct electrical impulses away from the neuron's cell body. Glial cells are the support cells in the nervous system that provide various functions such as insulation and nutrient transport. Neurotransmitters are chemical messengers that facilitate communication between neurons.

Question 14

Which of the following statements regarding the nervous system is true?

Accepted Answer

Glial cells indeed outnumber neurons, with estimates suggesting a ratio of about 10 to 1. Glial cells play crucial roles in supporting and maintaining the nervous system, including providing structural support, insulation, and nutrients to neurons, as well as participating in signal transmission and the maintenance of homeostasis.

Question 15

The gaps between segments of myelin sheath that occur at regular intervals are called:

Accepted Answer

The gaps between segments of myelin sheath that occur at regular intervals are called nodes of Ranvier. These nodes are important for the propagation of electrical impulses along the axon of a neuron.

Question 16

The changes in the electrical potential of a neuron that are proportional to the amount of incoming stimulation from other neurons are called:

Accepted Answer

Graded potentials are changes in the electrical potential of a neuron that vary in magnitude and are proportional to the amount of incoming stimulation from other neurons. Resting potentials refer to the baseline, steady-state electrical potential of a neuron when it is not receiving any stimulation, while action potentials are brief electrical signals that occur when the electrical potential of a neuron exceeds a certain threshold. Polarized potentials is not a term commonly used in neuroscience.

Question 17

One of the functions of glial cells is to:

Accepted Answer

Glial cells, also known as neuroglia, are support cells in the nervous system that provide various functions to neurons, including absorbing toxins and providing nutrients. They do not directly affect the electrical impulses that transmit information between neurons, so choices A, C, and D are incorrect.

Question 18

Multiple sclerosis occurs when a person's own immune system specifically attacks:

Accepted Answer

Multiple sclerosis is a demyelinating disease, which means that the myelin sheath around nerve fibers in the central nervous system is damaged. The damage disrupts signals traveling along the nerve fibers and causes a wide range of symptoms. The immune system is thought to mistakenly attack the myelin sheath, leading to the damage.

Question 19

The synaptic cleft is a tiny gap between:

Accepted Answer

The definition of a synaptic cleft is that it is the tiny gap between the axon terminal of one neuron and the dendrites or cell body of the next neuron. Therefore, the correct choice is B.

Question 20

Surrounding neurons and holding them in place is one of the functions of ___________________.

Accepted Answer

Glial cells, also known as neuroglia or simply glia, are specialized cells in the nervous system that provide support and protection for neurons. They surround neurons and help to hold them in place, as well as provide nutrients, remove waste, and even play a role in communication between neurons. Axons and axon terminals are parts of neurons, while the myelin sheath is a specialized coating around some axons that helps to speed up neural transmission.

Quiz 3: Biological Foundations of Behaviour