Question 1

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

Accepted Answer

A) A typical neuron has a resting potential of -70mV, or about 5% the voltage of the battery. 
B) A typical neuron has a resting potential of -70V, or about 50x the voltage of the battery. 
C) A typical neuron has a resting potential of +70mV, or about 5% the voltage of the battery. 
D) A typical neuron has a resting potential of +70V, or about 50x the voltage of the battery.

Question 2

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

Accepted Answer

A) K+ 
B) Na+ 
C) It is an average of the two.

Question 3

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

A) all ions will flow out 
B) potassium in, sodium out 
C) chloride and sodium out, potassium in 
D) sodium in, potassium out

Question 4

In early vertebrates, which component of the brain was devoted largely to coordinating motor reflexes?

Accepted Answer

A) thalamus 
B) forebrain 
C) midbrain 
D) hindbrain

Question 5

The outside of a neuron is positively charged at resting potential.Why don't negative ions exit from the cell to normalize charge across the membrane?

Accepted Answer

A) The positive charge outside the cell repels negative ions. 
B) There are no negative ions inside the cell. 
C) All of the chloride ions are already outside the cell. 
D) The negative charge inside the cell is carried by large proteins that cannot diffuse through the membrane.

Question 6

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

Accepted Answer

A) True 
 B)False

Question 7

How do temporal and spatial summation improve the processing power of the brain?

Accepted Answer

A) Temporal summation allows circadian rhythms to regulate neuronal activity.Spatial summation allows latitude to regulate neuronal activity. 
B) Temporal summation allows a neuron to fire prolonged action potentials, and spatial summation allows a neuron to synapse onto new targets. 
C) Temporal and spatial summation both make the neuron more likely to fire action potentials. 
D) Temporal summation allows a neuron to recognize a persistent signal from a single presynaptic cell, and spatial summation allows a neuron to recognize a broad signal from multiple presynaptic cells.

Question 8

You accidentally consume botulinum toxin by eating a contaminated can of sausages.What do you predict will be the most harmful physiological effect?

Accepted Answer

A) slowed action potential conduction 
B) respiratory failure due to spastic paralysis (constant muscle contraction) 
C) respiratory failure due to flaccid paralysis (relaxed muscles) 
D) pupil dilation

Question 9

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

A) increase, sweating, sodium 
B) decrease, urination, calcium 
C) decrease, shivering, potassium 
D) increase, panting, oxygen

Question 10

Since there is a larger concentration of potassium ions inside a neuron, why is the inside of the neuron negative (-70mV) relative to the outside?

Accepted Answer

A) Potassium ions carry a negative charge. 
B) Negatively-charged proteins inside the cell counteract the charge of the potassium ions. 
C) The negative sign is just a historical convention. 
D) The high concentration of sodium ions outside the cell makes the inside negative by comparison.

Question 11

What would happen if the G-protein coupled receptor in heart cells that binds to ACh had a mutation that caused it to bind more tightly to the G-protein alpha subunit?

Accepted Answer

A) G-protein activation and K+ channel opening would happen more quickly.Heart rate may remain abnormally low, impairing response to stress. 
B) This would lead to K+ flow out of heart cells, causing increased hyperpolarization. 
C) G-protein activation and K+ channel opening would be slowed.Heart rate may remain abnormally high, especially following stress. 
D) This would lead to K+ flow into heart cells, causing increased depolarization.

Question 12

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

A) defects; somatic cells; oligodendrocytes; demyelination 
B) symptoms; motor neurons; Schwann cells; demyelination 
C) symptoms; sensory neurons; Schwann cells; fast axonal transport 
D) genotypes; dendrites; axons; fast axonal transport

Question 13

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

A) hydrogen 
B) potassium 
C) calcium 
D) sodium

Question 14

When acetylcholine stimulates the opening of ligand-gated ion channels on a postsynaptic cell, what is this event called?

Accepted Answer

A) neuromuscular junction 
B) temporal summation 
C) inhibitory postsynaptic potential (IPSP) 
D) excitatory postsynaptic potential (EPSP)

Question 15

What is the site of primary sensory integration in the brain?

Accepted Answer

A) medulla oblongata 
B) cerebrum 
C) cerebellum 
D) thalamus

Question 16

If K+ can exit the cell through leak channels, why don't they flow out until there are equal concentrations on both sides of the membrane?

Accepted Answer

A) K+ can act as an enzymatic cofactor, and most K+ ions are bound to cellular enzymes. 
B) The leak channels allow a very slow leak that cannot keep pace with active import of K+ ions. 
C) Chelator molecules trap K+ on the inside of the membrane. 
D) The negative electrical potential inside the cell creates a force that holds the K+ ions in.

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

A) axon 
B) synapse 
C) soma 
D) dendrite

Question 18

What additional factor is required to mediate the parasympathetic effects of acetylcholine?

Accepted Answer

A) G-protein coupled receptor 
B) GABA 
C) AMPAR 
D) habituation

Question 19

In contrast to these toxins, strychnine acts postsynaptically, to block glycine from binding to receptors on motor neurons.Would you expect the symptoms of strychnine poisoning to be more similar to those of botulinum or tetanus toxin?

Accepted Answer

A) botulinum 
B) tetanus toxin 
C) botulinum.

Question 20

Damage to the substantia nigra, a specific region of the basal ganglia, can produce the resting muscle tremors characteristic of what disease?

Accepted Answer

A) epilepsy 
B) Parkinson disease 
C) seizures 
D) Alzheimer disease

Exam 43: The Nervous System