Question 1

Mutation of the peripheral myelin protein 22 (PMP22) gene, which causes demyelination of peripheral neurons, is a more common cause of Charcot-Marie-Tooth disease.In which cells is the PMP22 gene important for normal function?

Accepted Answer

The PMP22 gene is important for the normal function of Schwann cells, which are responsible for the myelination of peripheral nerves.

Question 2

To process information, postsynaptic neurons often add up simultaneous signals from several presynaptic neurons.Which structure and process allow them to do so?

Accepted Answer

Dendrites allow for spatial summation, which is the process of adding up signals from different presynaptic neurons that are synapsed onto different regions of the dendrites. Temporal summation, on the other hand, occurs when the signals from a single presynaptic neuron occur in rapid succession and sum up over time, which is facilitated by axons.

Question 3

What do the two sets of neurons damaged in Charcot-Marie-Tooth neuropathy comprise?

Accepted Answer

Charcot-Marie-Tooth neuropathy primarily affects the peripheral nervous system, which includes motor and sensory neurons.

Question 4

Is the resting membrane potential of a neuron closer to the equilibrium potential for K⁺ or Na⁺?

Accepted Answer

The resting membrane potential is closer to the equilibrium potential for potassium ions (K⁺) because the permeability of the cell membrane to potassium ions is much higher than it is to sodium ions. As a result, the resting membrane potential is closer to the equilibrium potential for potassium. This is why the resting membrane potential is often referred to as the potassium equilibrium potential.

Question 5

A neuron that engages in spatial summation acquires a mutation that causes dendrite overgrowth and promiscuous synapsing.What is the likely outcome?

Accepted Answer

Dendrite overgrowth and promiscuous synapsing would increase the number of inputs the neuron receives, leading to a higher likelihood of spatial summation and therefore an abnormally high frequency of action potentials.

Question 6

What part of the neuron is responsible for most of the "house-keeping" tasks of the cell, including protein synthesis?

Accepted Answer

The soma, or cell body, contains the nucleus and is responsible for most of the neuron's metabolic activities, including protein synthesis.

Question 7

You are an EMT on duty for the marathon.It is an extremely hot day.You say to your partner, "This weather is likely to _____________ the risk of hyponatremia, because ______________ will cause the athletes to lose ______________."

Accepted Answer

The hot weather increases sweating, which can lead to a loss of sodium, thereby increasing the risk of hyponatremia.

Question 8

What branched structure allows a neuron to take in information from more than one source?

Accepted Answer

Dendrites are branched structures of a neuron that receive signals from other neurons, allowing the neuron to take in information from multiple sources.

Question 9

Subsequent to motor neuron degeneration in Charcot-Marie-Tooth disease, muscles begin to weaken and degenerate as well.What is the likely cause?

Accepted Answer

Muscles will atrophy if they don't receive regular stimulation from motor neurons. Without regular stimulation from motor neurons, muscles will start to weaken and eventually degenerate due to lack of use. This is why physical therapy and exercise can be beneficial for people with Charcot-Marie-Tooth disease, as it can help to maintain muscle function and prevent further degeneration.

Question 10

If you were to compare the resting potential of a neuron to a battery, which way is the battery oriented?

Accepted Answer

The resting potential of a neuron is characterized by a higher concentration of positive ions outside the cell and negative ions inside, similar to a battery with the positive terminal outside and the negative terminal inside.

Question 11

Marathon runners are encouraged to stop at water stations along the course to stay hydrated.However, occasionally a runner drinks too much water and suffers from hyponatremia, or "water intoxication".While water itself is not toxic, drinking too much can upset ion balance in the extracellular space.Based on what you know about ions and nerve signaling, the levels of which important ion are most likely to be disrupted in hyponatremia?

Accepted Answer

Hyponatremia is characterized by low sodium levels in the blood, which disrupts nerve signaling and cellular function.

Question 12

How does the resting potential of a typical neuron compare to that of a 1.5V AA alkaline battery?

Accepted Answer

A typical neuron has a resting potential of -70mV, which is about 5% of the 1.5V of an AA alkaline battery.

Question 13

Your roommate is on an ultra-low fat diet to try to lose weight.Given what you know about structure of the nervous system, what advice would you give him?

Accepted Answer

The myelin sheaths around axons in the nervous system are made up of fatty acids, including unsaturated ones. Therefore, it is important for the roommate to consume some healthy unsaturated fats, such as those found in fish, olive oil, and nuts, to support the health and function of their nervous system. Drinking water is important for overall health but does not directly affect the nervous system. Losing weight through extreme methods may actually harm the brain, and consuming trans fats is known to be harmful to overall health.

Question 14

True or false: When a neuron is not firing, the sodium-potassium pump is inactive.

Accepted Answer

The sodium-potassium pump is always active, even when the neuron is not firing, as it maintains the resting membrane potential.

Question 15

True or false: neurons are the only electrically-active cells.

Accepted Answer

While neurons are well-known for their electrical activity, other cells such as muscle cells and some types of gland cells also have the ability to generate electrical signals.

Question 16

How can mutations in different genes, functioning in different cells, lead to the same disease? From the following, choose the best responses to complete the sentences: "Physiological function requires that multiple cells work together.Various defects in different cells can impair function, leading to ___________ that are indistinguishable at the level of the whole organism.In Charcot-Marie-Tooth disease, motor nerve function can be impaired either by a problem within _______________ , or a problem in __________________ causing _______________."

Accepted Answer

Charcot-Marie-Tooth disease is a hereditary peripheral neuropathy that affects both motor and sensory nerves. Mutations in genes functioning in motor neurons or Schwann cells can lead to demyelination and impairment of motor nerve function, resulting in similar symptoms in affected individuals. Option A is incorrect since oligodendrocytes are not involved in peripheral nerve function. Option C and D are also incorrect as they do not pertain to Charcot-Marie-Tooth disease.

Question 17

Genetic studies have found that Charcot-Marie-Tooth may be caused by a mutation in the gene Mitofusin-2 (MFN2), which causes mitochondria to form large clumps.In what area of a neuron are these clumps most likely to cause a problem?

Accepted Answer

The axon is the part of the neuron responsible for transmitting signals over long distances. Mitochondrial dysfunction in the axon can disrupt energy supply and transport, leading to neurodegenerative issues like those seen in Charcot-Marie-Tooth disease.

Question 18

A Hawaiian legend tells of a village that angered a shark god.In revenge, a "seaweed" began to grow in the tidepools that killed anyone who touched it.In fact, this "limu-make-o-Hana" -- a zoanthid cnidarian -- contains a palytoxin that locks the sodium-potassium pump open, allowing free flow of ions.If a villager suffers palytoxin poisoning, which way will the ions in his neurons flow?

Accepted Answer

Palytoxin locks the sodium-potassium pump open, disrupting its normal function. Normally, the pump moves sodium out of the cell and potassium into the cell. When the pump is locked open, sodium flows into the cell and potassium flows out, following their concentration gradients.

Question 19

A patient suffers from a disease that slows fatty acid synthesis.What is a likely impact of this disease on nervous system function?

Accepted Answer

Fatty acids are important for the formation of myelin, the insulating layer around axons that increases the speed of nerve impulse transmission. A disease that slows fatty acid synthesis could lead to insufficient myelination and a slow axon conduction rate, which could impact nervous system function.

Question 20

Three-quarters of the substantial amount of energy consumed by the brain is used to run a single molecular machine that maintains the resting potential of neurons.What is this machine called?

Accepted Answer

The sodium-potassium pump is responsible for maintaining the resting potential of neurons by actively transporting sodium and potassium ions across the cell membrane, which consumes a significant amount of energy.

Quiz 43: The Nervous System

Mutation of the peripheral myelin protein 22 (PMP22) gene, which causes demyelination of peripheral neurons, is a more common cause of Charcot-Marie-Tooth disease.In which cells is the PMP22 gene important for normal function?

To process information, postsynaptic neurons often add up simultaneous signals from several presynaptic neurons.Which structure and process allow them to do so?

What do the two sets of neurons damaged in Charcot-Marie-Tooth neuropathy comprise?

Is the resting membrane potential of a neuron closer to the equilibrium potential for K⁺ or Na⁺?

A neuron that engages in spatial summation acquires a mutation that causes dendrite overgrowth and promiscuous synapsing.What is the likely outcome?

What part of the neuron is responsible for most of the "house-keeping" tasks of the cell, including protein synthesis?

You are an EMT on duty for the marathon.It is an extremely hot day.You say to your partner, "This weather is likely to _ the risk of hyponatremia, because will cause the athletes to lose ____."

What branched structure allows a neuron to take in information from more than one source?

Subsequent to motor neuron degeneration in Charcot-Marie-Tooth disease, muscles begin to weaken and degenerate as well.What is the likely cause?

If you were to compare the resting potential of a neuron to a battery, which way is the battery oriented?

How does the resting potential of a typical neuron compare to that of a 1.5V AA alkaline battery?

Your roommate is on an ultra-low fat diet to try to lose weight.Given what you know about structure of the nervous system, what advice would you give him?

True or false: When a neuron is not firing, the sodium-potassium pump is inactive.

True or false: neurons are the only electrically-active cells.

Genetic studies have found that Charcot-Marie-Tooth may be caused by a mutation in the gene Mitofusin-2 (MFN2) , which causes mitochondria to form large clumps.In what area of a neuron are these clumps most likely to cause a problem?

A patient suffers from a disease that slows fatty acid synthesis.What is a likely impact of this disease on nervous system function?

Three-quarters of the substantial amount of energy consumed by the brain is used to run a single molecular machine that maintains the resting potential of neurons.What is this machine called?

Quiz 43: The Nervous System

Mutation of the peripheral myelin protein 22 (PMP22) gene, which causes demyelination of peripheral neurons, is a more common cause of Charcot-Marie-Tooth disease.In which cells is the PMP22 gene important for normal function?

To process information, postsynaptic neurons often add up simultaneous signals from several presynaptic neurons.Which structure and process allow them to do so?

What do the two sets of neurons damaged in Charcot-Marie-Tooth neuropathy comprise?

Is the resting membrane potential of a neuron closer to the equilibrium potential for K+ or Na+?

A neuron that engages in spatial summation acquires a mutation that causes dendrite overgrowth and promiscuous synapsing.What is the likely outcome?

What part of the neuron is responsible for most of the "house-keeping" tasks of the cell, including protein synthesis?

You are an EMT on duty for the marathon.It is an extremely hot day.You say to your partner, "This weather is likely to _____________ the risk of hyponatremia, because ______________ will cause the athletes to lose ______________."

What branched structure allows a neuron to take in information from more than one source?

Subsequent to motor neuron degeneration in Charcot-Marie-Tooth disease, muscles begin to weaken and degenerate as well.What is the likely cause?

If you were to compare the resting potential of a neuron to a battery, which way is the battery oriented?

How does the resting potential of a typical neuron compare to that of a 1.5V AA alkaline battery?

Your roommate is on an ultra-low fat diet to try to lose weight.Given what you know about structure of the nervous system, what advice would you give him?

True or false: When a neuron is not firing, the sodium-potassium pump is inactive.

True or false: neurons are the only electrically-active cells.

Genetic studies have found that Charcot-Marie-Tooth may be caused by a mutation in the gene Mitofusin-2 (MFN2) , which causes mitochondria to form large clumps.In what area of a neuron are these clumps most likely to cause a problem?

A patient suffers from a disease that slows fatty acid synthesis.What is a likely impact of this disease on nervous system function?

Three-quarters of the substantial amount of energy consumed by the brain is used to run a single molecular machine that maintains the resting potential of neurons.What is this machine called?

Is the resting membrane potential of a neuron closer to the equilibrium potential for K⁺ or Na⁺?

You are an EMT on duty for the marathon.It is an extremely hot day.You say to your partner, "This weather is likely to _ the risk of hyponatremia, because will cause the athletes to lose ____."