106. Terrance went to the dentist and was given some Novocain. This prevented him from feeling pain because the drug ____.
a. attached to sodium channels letting in sodium and stopping the action potential from sending a pain message
b. attached to potassium channels letting in potassium and stopping the action potential from sending a pain message
c. attached to potassium channels blocking potassium from entering and stopping the action potential from sending a pain message
*d. attached to sodium channels blocking sodium from entering and stopping the action potential from sending a pain message
107. Dr. Blanchard is giving a lecture about the propagation of the action potential. What would she tell the class?
*a. That the process of an action potential repeats itself over and over down the length of the axon thanks to the diffusion of sodium ions.
b. That the process of an action potential repeats itself over and over down the length of the axon thanks to the diffusion of potassium ions.
c. The action potential moves down the length of the axon because all the sodium channels open all at once after the neuron reaches threshold.
d. The action potential moves down the length of the axon because all the potassium channels open all at once after the neuron reaches threshold.
108. Dr. Ruggs is giving a lecture about the all-or-none-law. What would she tell the class?
a. That all neurons produce an action potential at the same time or none produce one.
b. That all neurons are active at the same time or none at all.
c. That all ion channels open at the same time or none at all.
*d. That after reaching threshold, the amplitude and velocity of the action potential is the same each time.
109. The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____.
a. concentration gradient
*b. refractory period
c. sodium potassium pump
d. phospholipid bilayer
110. During the relative refractory period, the ____.
a. sodium gates are firmly closed
*b. sodium gates are reverting to their usual state
c. sodium gates are wide open
d. potassium gates are firmly closed
111. What will most affect the speed of an action potential?
a. The strength of the stimulus
b. The time since the last action potential
c. The length of the axon
*d. The resistance of the membrane
112. The speed of an action potential down an unmyelinated axon is best described as ____.
a. the speed of electricity, regardless of the size of the axon
b. less than 1 meter per second, regardless of the size of the axon
c. faster in thin axons than in thick ones
*d. faster in thick axons than in thin ones
113. Professor Cook is lecturing on the importance of the myelin sheath. He told that class that _____.
a. myelin is the only structure that can prevent action potentials from traveling the wrong direction.
*b. the fatty nature of the myelin speeds up the action potential down the length of the axon
c. the fatty nature of myelin provide storage for key nutrients for the neuron
d. myelin increases the strength of the action potential
114. In what direction does a local neuron transmit information?
a. Through its dendrites to cell body to axon
b. Through its axon to cell body to dendrites
c. Only toward the cell body
*d. Equally well in any direction
115. Which of the following describes the transmission of information in a local neuron?
*a. The signal decreases in strength as it travels.
b. The signal increases in strength as it travels.
c. The signal strength remains constant as it travels.
d. Local neurons do not transmit any information.
116. Describe the structure of the blood-brain barrier and explain why it is important.
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