Question 1

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

Axon terminals are the branches at the end of an axon that make synaptic connections with other neurons' dendrites.

Question 2

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

Accepted Answer

Depolarization occurs when the neuron's membrane potential becomes less negative (more positive), moving from -70 millivolts to +40 millivolts, indicating the neuron is becoming active.

Question 3

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

Accepted Answer

The gaps between segments of the myelin sheath are known as nodes of Ranvier, which facilitate rapid conduction of nerve impulses.

Question 4

The resting potential of the typical neuron is determined by:

Accepted Answer

The resting potential is primarily due to a higher concentration of positive ions (Na+) outside the neuron and negative ions (K+ and proteins) inside, creating a negative charge inside relative to the outside.

Question 5

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

Accepted Answer

The myelin sheath acts as an insulator and allows for faster transmission of electrical impulses along the axon through saltatory conduction, where the impulse jumps between nodes of Ranvier.

Question 6

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

Accepted Answer

Glial cells are responsible for supporting neurons, holding them in place, and providing them with nutrients and other forms of support.

Question 7

The changes in the electrical potential of a neuron that do not reach -50 millivolts are called:

Accepted Answer

Graded potentials are changes in the electrical potential of a neuron that do not reach the threshold of -50 millivolts required to trigger an action potential.

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 absolute refractory period is the time immediately following an action potential during which a neuron is unable to fire another impulse, regardless of the strength of the stimulus.

Question 9

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 that support the equipment are analogous to the body's _.

Accepted Answer

Glial cells in the body support and maintain the neurons, similar to how technicians and mechanics support and maintain the communication network's equipment.

Question 10

Branchlike 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 branchlike structures that receive messages from other neurons and transmit them to the cell body.

Question 11

The role of the blood-brain barrier is to:

Accepted Answer

The blood-brain barrier acts as a selective permeability barrier that prevents many foreign substances, including toxins and pathogens, from entering the brain, thus protecting the central nervous system.

Question 12

That action potentials occur at a uniform and maximum intensity or they do not occur at all is known as:

Accepted Answer

The all-or-none law states that an action potential either occurs at full intensity or not at all, regardless of the strength of the stimulus, as long as it reaches the threshold.

Question 13

The resting potential of a typical neuron is:

Accepted Answer

The typical resting potential of a neuron is -70 millivolts. This is the difference in electrical charge between the inside and outside of the neuron cell membrane when the neuron is at rest.

Question 14

When a neuron is stimulated, tiny protein structures on the cell membrane are activated that 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 neuron's cell membrane that allow ions to move in and out, changing the neuron's potential.

Question 15

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

Accepted Answer

Glial cells are more numerous than neurons, with estimates suggesting they outnumber neurons by about 10 to 1.

Question 16

The function of the axon is to:

Accepted Answer

The axon is responsible for transmitting electrical messages from the cell body to other neurons, muscles, or glands.

Question 17

One of the functions of glial cells is to:

Accepted Answer

Glial cells absorb toxins that might damage neurons.

Question 18

It is relatively easy to see how there can be trillions of interconnections in the brain, given the diverse structures of the _.

Accepted Answer

The axon and the dendrites are key structures in neurons that form synapses, allowing for trillions of interconnections in the brain.

Question 19

The synaptic cleft is a tiny gap between:

Accepted Answer

The synaptic cleft is the small gap between the axon terminal of one neuron and the dendrite of the next neuron, where neurotransmitters are released to transmit signals.

Question 20

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

Accepted Answer

Multiple sclerosis is an autoimmune disease where the immune system attacks the myelin sheath, the protective covering of nerve fibers in the central nervous system.

Quiz 3: Biological Foundations of Behaviour