Cell Bio final: 22

Which of these structures transmit signals from the central nervous system to muscles? A)sensory neurons B)Schwann cells C)motor neurons D)glial cells

C)motor neurons

_________________ refractory periods are those where a new action potential is possible but difficult to initiate.

Relative

The refractory period - once a region of the membrane has experienced an action potential, it becomes ________________ unresponsive and _____________ of undergoing another action potential.

temporarily, incapable

CB1 agonists such as Tetrahydrocannabinol (THC) reduce calcium influx by blocking the activity of voltage-dependent calcium channels. What effect would this have on the release of glutamate? A)Exocytosis of vesicles containing glutamate from the nerve terminal would decrease. B)Exocytosis of vesicles containing glutamate from the nerve terminal would increase. C)There will be no effect.

A)Exocytosis of vesicles containing glutamate from the nerve terminal would decrease.

The __________ technique keeps a cell at a fixed membrane potential and measures tiny changes in __________ in a cell. Bloom's Taxonomy: Application/Analysis A)voltage meter; potential B)patch clamp; current C)voltage sensor; current D)patch clamp; pressure

B)patch clamp; current

Which of the following is true when comparing voltage-gated sodium and voltage-gated potassium channels? A)Voltage-gated sodium channels are made up of monomeric proteins, whereas voltage-gated potassium channels are made up of multiple protein subunits. B)Sodium channels are multimeric proteins, whereas potassium channels are monomeric proteins. C)Voltage-gated sodium channels are sensitive to changes in the membrane potential, whereas the voltage-gated potassium channel is not. D)Both channels are made up of both multimeric and monomeric proteins.

A)Voltage-gated sodium channels are made up of monomeric proteins, whereas voltage-gated potassium channels are made up of multiple protein subunits.

Which of the following would induce synaptic release of neurotransmitter in the absence of an action potential in a neuron? A)application of a calcium ionophore that equilibrated calcium between the cytoplasm of the synaptic terminal and the extracellular space B)demyelination of the axon C)inhibition of neurotransmitter receptors in the dendrites of the axons D)increasing the rate of neurotransmitter removal from the synaptic cleft

A)application of a calcium ionophore that equilibrated calcium between the cytoplasm of the synaptic terminal and the extracellular space

Which of these substances is NOT a neurotransmitter for a chemical synapse? A)calcium B)catecholamines C)glycine D)acetylcholine

A)calcium

A chemical synapse __________. A)uses neurotransmitters in the synaptic cleft B)has a presynaptic and postsynaptic neuron that are directly connected C)has a presynaptic and postsynaptic neuron coupled by a gap junction D)uses channels formed by proteins called connexons

A)uses neurotransmitters in the synaptic cleft

__________________ refractory periods are due to the inactivation of sodium channels.

Absolute

What is the role of calcium at the synaptic terminal? A)Depolarization of the synaptic terminals by an invading action potential opens voltage-gated calcium channels at the terminal, thus permitting diffusion of calcium out of the synaptic terminal. B)Depolarization of the synaptic terminals by an invading action potential releases intracellular calcium stores or allows calcium channels to open to allow calcium to enter the synaptic terminal from the extracellular environment, thus permitting neurotransmitter release. C)Calcium, like sodium, is out of both ionic and electrical equilibrium. Therefore, it counteracts the loss of free energy following depolarization of the synaptic terminal. D)Calcium enters the synaptic terminal, permitting water to enter, increasing hydrostatic pressure, and forcing neurotransmitter out of the terminal into the synapse.

B)Depolarization of the synaptic terminals by an invading action potential releases intracellular calcium stores or allows calcium channels to open to allow calcium to enter the synaptic terminal from the extracellular environment, thus permitting neurotransmitter release.

Which of these statements describes the mechanism of voltage-gated channel proteins? A)If the membrane voltage reaches threshold, ions are pumped through. B)If the membrane voltage reaches threshold, ions can diffuse through. C)Neurotransmitters can move through only if the overall membrane voltage stays the same. D)Ions can move through only if the overall membrane voltage stays the same.

B)If the membrane voltage reaches threshold, ions can diffuse through.

Which of the following summaries concerning cells of the nervous system is accurate? A)Glia are excitable cells that are designed to send and receive information in the form of electrical impulses. Glia often accomplish this by receiving a stimulus, converting the stimulus into a change in membrane potential, and finally converting the change in membrane potential into chemical signals that are released at synaptic connections. Neurons are support cells in high abundance in the nervous system that act to protect, electrically insulate, and control nutrient delivery to glia via the blood-brain barrier. B)Neurons are excitable cells that are designed to send and receive information in the form of electrical impulses. Neurons often accomplish this by receiving a stimulus, converting the stimulus into a change in membrane potential, and finally converting the change in membrane potential into chemical signals that are released at synaptic connections. Glia are support cells in high abundance in the nervous system that act to protect, electrically insulate, and control nutrient delivery to neurons via the blood-brain barrier. C)Neurons are excitable cells that are designed to send and receive information in the form of chemical impulses. Neurons often accomplish this by receiving a stimulus, converting the stimulus into a chemical message, and finally converting chemical message into a change in membrane potential that is released at synaptic connections. Glia are support cells in high abundance in the nervous system that act to protect, electrically insulate, and control nutrient delivery to neurons via the blood-brain barrier. D)Neurons are excitable cells that are designed to send information in the form of electrical impulses. Neurons often accomplish this by generating a stimulus, converting the stimulus into a change in membrane potential, and finally converting the change in membrane potential into chemical signals that are released at synaptic connections. Glia are support cells in high abundance in the nervous system that act to receive information.

B)Neurons are excitable cells that are designed to send and receive information in the form of electrical impulses. Neurons often accomplish this by receiving a stimulus, converting the stimulus into a change in membrane potential, and finally converting the change in membrane potential into chemical signals that are released at synaptic connections. Glia are support cells in high abundance in the nervous system that act to protect, electrically insulate, and control nutrient delivery to neurons via the blood-brain barrier.

Glutamate causes the membrane of postsynaptic neurons to become hyperpolarized. How would THC be expected to affect the rate of nerve impulse transmission in postsynaptic neurons that make synapses with the glutamatergic neuron? A)The rate would decrease. B)The rate would increase. C)The rate would not change.

B)The rate would increase.

A __________ is a collection of __________ from __________ that innervate effector organs and typically appear white due to __________ Bloom's Taxonomy: Knowledge/Comprehension A)dendrite; axon hillocks; neurons; neurotransmitters B)nerve; axons; neurons; myelin C)neuron; dendrites; glia; myelin D)nerve; dendrites; myelin; neurons

B)nerve; axons; neurons; myelin

Which of the following accurately explains why a nerve impulse can move only away from the initial site of depolarization? A)Calcium influx prevents it from moving toward the initial site of depolarization. B)Potassium channels prevent it from moving toward the initial site of depolarization. C)Sodium channels are permanently inactivated after the initial depolarization event. D)Sodium channels that were previously opened during the action potential have been inactivated and cannot immediately respond to further stimulation.

D)Sodium channels that were previously opened during the action potential have been inactivated and cannot immediately respond to further stimulation.

A mutant sodium channel has been discovered that opens faster and allows more sodium to enter the cell compared to the wild-type sodium channel. What experimental evidence would verify this? A)The hyperpolarizing phase would move to more negative values. B)The width of the peak of the action potential would increase. C)The slope of the falling phase of the action potential would be greater. D)The slope of the rising phase of the action potential would be greater and the peak would be higher.

D)The slope of the rising phase of the action potential would be greater and the peak would be higher.

The resting membrane potential __________. A)occurs when all ions are at equilibrium B)occurs when the Na+/K+ pump is inactive C)occurs at a membrane potential of 0 D)occurs when all ion movements stabilize at constant rates

D)occurs when all ion movements stabilize at constant rates

Cells at rest normally have an excess of __________ inside and an excess of __________ outside the cell. This generates a resting membrane potential of approximately __________. A complete action potential results in __________ moving into the cell and __________ moving out of the cell. A)chloride; calcium; +60 mV; sodium; potassium B)potassium; sodium; −60 mV; potassium; sodium C)sodium; potassium; −60 mV; sodium; potassium D)potassium; sodium; −60 mV; sodium; potassium

D)potassium; sodium; −60 mV; sodium; potassium

Which answer shows the correct order of occurrence during an action potential? A)resting state, hyperpolarizing phase, depolarizing phase, repolarizing phase B)depolarizing phase, hyperpolarizing phase, repolarizing phase, resting state C)hyperpolarizing phase, depolarizing phase, repolarizing phase, resting state D)resting state, depolarizing phase, repolarizing phase, hyperpolarizing phase

D)resting state, depolarizing phase, repolarizing phase, hyperpolarizing phase

It can be divided into two periods known as the ______________ and ________________ refractory periods.

absolute, relative