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126 Cards in this Set
- Front
- Back
What is the order of transmission of information within a neuron?
arrange: cell body, dendrite, axon |
dendtrite, cell body, axon
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What are the two kinds of cells in the nervous system?
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neurons and glia
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Neurons differ most strongly from other body cells in their:
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shape
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What happens to a virus that manages to cross the blood-brain barrier and enter the brain?
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It stays in the nervous system throughout a person's life
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Neurons typically have one ____, but many ____.
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axon, dendrites
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Glucose enters the brain via:
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active transport
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What would a neuron in the pons be called that receives information only from other cells in the pons and sends information only to other cells in the pons?
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intrinsic
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What receives excitation from other neurons and conducts impulses to muscle or gland cells?
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motor neurons
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Why does the brain need thiamine?
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To enable it to metabolize glucose the brain needs ________
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Incoming synapses are primarily found on:
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dendrites and cell bodies
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Who is most likely to suffer from a thiamine deficiency?
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alcoholics
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Which chemicals flow most freely across a cell membrane?
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water, oxygen, carbon dioxide
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A greater amount of branching on dendrites allows them to:
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dendrites have a larger surface area available for receiving information from other neurons when they have _______.
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In the brain, an arrangement of endothelial cells:
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does not allow most molecules to pass because the cells are so tightly packed
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Chemicals are released by axons:
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into the junctions between the neurons
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One type of glia helps synchronize the activity of axons. They are called:
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astrocytes
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Where do the metabolic activities occur that provide energy for all of the other activities of the cell?
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mitochondria does what for the cell?
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Myelin covers:
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Some axons in vertebrates and non in invertebrates are covered by _______.
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What is the main source of nutrition for vertebrate neurons?
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glucose is the main source of ___________ for neurons
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Korsakoff's syndrome is marked by:
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severe memory impairments
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What are dendrites?
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branching fibers that get narrower at their ends are called:
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What leads to Korsakoff's syndrome?
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A thiamine deficiency caused by alcoholism causes what?
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Why do neurons rely so heavily on glucose as their source of nutrition?
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other fuels do not readily cross the blood-brain barrier
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Ribosomes are the part of a cell that:
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synthesize new proteins
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Which of the following is NOT a characteristic of a dendrite?
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it is in contact with dendrites of other neurons
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What is the mechanism that prevents or slows some chemicals from entering the brain, while allowing others to enter?
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a blood-brain barrier
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What is the point from which an axon releases chemicals into the synapse?
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the presynaptic terminal
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Compared to passive transport, the major disadvantage of active transport is that it:
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requires the expenditure of energy
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Nodes of Ranvier are:
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the gaps in myelin of axons
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The insulating material which covers many vertebrate axons is called the:
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myelin sheath
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Which type of glia builds myelin sheaths around axons in the periphery of the body?
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Schwann Cells
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What are two requirements for the brain to metabolize glucose?
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thiamine and oxygen
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The risk of having part of the brain unprotected by the blood-brain barrier is:
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Both chemical interference with neurotransmitters and increased risk for viruses and toxic chemicals are correct
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Glial cells:
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do not transmit information over long distances
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The endoplasmic reticulum is a:
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network of thin tubes that transport newly synthesized proteins
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What type of glial cells myelinate axons in the brain and spinal cord?
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ogliodendrocytes
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The major disadvantage of a blood-brain barrier is that:
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certain required chemicals must be actively transported
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Which of the following is a characteristic of glial cells in the human brain?
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they are more numerous than neurons
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The information sender of the neuron, conveying an impulse toward either other neurons or a gland or muscle is called the:
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the axon
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In contrast to dendrites, axons:
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may be covered in myelin
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Molecules that can cross the blood-brain barrier are usually:
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molecules that can dissolve in the fats of the capillary walls
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Many dendrites contain short outgrowths called spines which:
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increase the surface area available for synapses
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Some dendrites contain additional short outgrowths. What are these outgrowths called?
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dendritic spines
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As a general rule, where do axons convey information?
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away from their own cell body
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If you were to accidentally touch a hot stove with your hand, you would quickly pull your hand away. The information carried to the muscles in your arm to make them contract was carried by:
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efferent neurons
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The structure that contains the chromosomes is called the:
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nucleus
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A presynaptic terminal is also known as:
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an end bulb
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Chemicals than cannot flow freely across a cell membrane enter a neuron through:
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specialized protein channels
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The branching fibers that form the information-receiving pole of the nerve cells are called:
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dendrites
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the most important consideration in developing a drug that will act in the brain is:
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if the drug will cross the blood-brain barrier
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Radial glia:
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guide the migration of neurons in embryonic development
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Which function is NOT performed by glia?
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transmitting information
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Glial cells
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occupy the same total space as do neurons
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Protein channels, allow ____ to cross the cell membrane.
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small charged molecules
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Glial cells whose function most closely resembles that of the immune system are called:
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microglia
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What is the approximate resting potential of the inside of a neuron's membrane, relative to the outside?
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-70mV
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Which of the following events would increase the concentration gradient of sodium?
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Increased activity of the sodium potassium pump
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Which feature of a neuron limits the number of action potentials it can produce per second?
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the absolute refractory period
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Which of the following actions would depolarize a neuron?
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Increasing membrane permeability to sodium
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When a neuron's membrane is at rest, which of the following molecules crosses through it MOST slowly?
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potassium
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In a myelinated axon, where are sodium gates abundant?
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Nodes of Ranvier
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If there is a depolarizing effect on a neuron, the result will be that the neuron will fire:
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only if it reaches threshold
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If you were to stub your toe and feel the pressure a second or two before you feel the pain, then which of the following statements is most likely true?
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pressure sensitive neurons are large and myelinated
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Which of the following is TRUE of local neurons?
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they have short dendrites and axons
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What are the nodes of Ranvier?
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Gaps in the myelin sheath
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Which of the following is an advantage of having a resting potential?
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the cell is prepared to respond quickly to any stimulus
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When a neuron’s membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell.
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out of, into
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The sodium-potassium pump, repeatedly transports three ____ ions out of the cell while drawing two ____ ions into it.
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Sodium, potassium
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After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?
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sodium gates in the membrane close
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When the neuron is at rest, what is responsible for moving sodium ions out of the cell?
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the sodium potassium pump
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When a neuron’s membrane is at rest, the concentration gradient tends to move sodium ____ the cell and the electrical gradient tends to move it ____ the cell.
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into, into
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What disease is related to the destruction of myelin sheaths?
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multiple sclerosis
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What is the difference in voltage called that typically exists between the inside and the outside of a neuron?
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resting potential
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Which of the following describes selective permeability?
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only certain molecules are allowed to cross the membrane freely
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At the peak of the action potential, the electrical gradient:
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pushes potassium out of the cell
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Which of the following would produce a hyperpolarization of a neuron?
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applying a negative charge inside the neuron with a micro electrode
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What tends to open the sodium gates across a neuron's membrane?
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depolarization of the membrane
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What is one major cause for the resting potential of a neuron's membrane?
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the sodium potassium pump
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In what way is a myelinated axon that has lost its myelin (through disease) different from an axon that was never myelinated?
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it lacks sodium gates along parts of its surface
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How is the speed of an action potential down an unmyelinated axon BEST described?
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faster in thicker axons than thinner axons
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The neuron will produce an action potential only if the depolarization exceeds what level?
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the threshold of excitation
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In what direction does a local neuron transmit information?
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equally well in any direction
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Concentration gradients lead to what kind of movements?
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the movements of ions to areas of their lowest concentration
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The all-or-none law applies to:
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axons
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During the relative refractory period:
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the sodium gates are returning to their usual state
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When the potential across a membrane reaches threshold, the sodium channels:
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open to let sodium enter the cell rapidly
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The presence of an all-or-none law suggests that neurons can only convey different messages by changing their:
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rate or pattern of action potentials
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What causes potassium ions to leave the axon just after the peak of the action potential?
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a continuing concentration gradient and the opening of the potassium pumps
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The membrane of a neuron is composed of ____ with ____ embedded in them.
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fat molecules; proteins
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If depolarization is less than the cell's threshold:
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sodium crosses the membrane only slightly more than usual
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Under which conditions would the sodium-potassium pump be far less effective in creating a concentration gradient?
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if the plasma membrane were generally permeable
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What is the result if a stimulus shifts the potential inside a neuron from the resting potential to a potential slightly closer to zero?
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depolarization
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When you state that the neuron's membrane is polarized, you are referring to a difference in electrical potential between:
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the inside and outside of the membrane
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Local anesthetic drugs, such as Novocain, work by:
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blocking the sodium gates
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Voltage-activated channels are channels for which a change in the voltage across the membrane alters their:
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permeability
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Stimulus A depolarizes a neuron just barely above the threshold. Stimulus B depolarizes a neuron to 10 mV beyond threshold. What can we expect to happen?
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Stimulus A and Stimulus B will produce the same response in the neurons
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A drug that decreases the flow of potassium through the potassium gates of the membrane would:
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slow the return of the membrane to its resting potential
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To what does saltatory conduction refer?
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the transmission of an impulse along a myelinated axon
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Which of the following represents the all-or-none law?
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the size of the action potential is independent of the strength of the stimulus that initiated it
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The membrane of a neuron is specialized to:
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control the exchange of chemicals between the inside and outside of the cell
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During the entire course of events from the start of an action potential until the membrane returns to its resting potential, what is the net movement of ions?
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sodium in potassium out
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Ordinarily, stimulation of a neuron takes place:
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at the synapse
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Saltatory conduction ____ the velocity of action potentials, and ____ the amount of energy used by the neuron.
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increases, decreases
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The selectivity of a neuron membrane is analogous to?
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the blood-brain barrier
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At what point do the sodium gates start to allow sodium into the neuron?
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in response to any depolarization
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What happens once an action potential starts?
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it is regenerated at other points along the axon
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A drug that blocks the sodium gates of a neuron's membrane would:
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block the action potential
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In the normal course of an action potential:
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sodium remains much more concentrated on the outside than inside of the neuron
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What is the result if a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?
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hyperpolarization
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Negatively charged ions like ____ are mostly located outside the cell.
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chloride
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Electrical gradients lead to what kind of movements?
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the movement of ions to areas having the opposite charge
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Suppose we applied a drug to a neuron that caused its sodium gates to suddenly open wide. What would happen?
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an action potential
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Which of the following is NOT governed by the all-or-none law?
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local neurons
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Just after the peak of the action potential, what movement of ions restores the membrane to approximately the resting potential?
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potassium ions leave the cell
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The presence of myelin and the diameter of the axon:
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affect the speed of the action potential
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Why are local neurons more difficult to study?
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they are so small
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The action potential of a neuron depends mostly on what movement of ions?
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sodium ions entering the cell
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The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the:
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absolute refractory period
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What is meant by the term "concentration gradient" with respect to neurons?
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sodium and potassium ions are more concentrated on opposite sides of the membrane
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A neuron's sodium gates are firmly closed and the membrane cannot produce an action potential during:
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the absolutely refractory period
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The function of a myelin sheath is to:
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increase the velocity of the action potential along an axon
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The resting potential of a neuron refers to:
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the net negative charge on the inside of the neuron
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Which of the following describes the transmission of information in a local neuron?
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the signal decreases in strength as it travels
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When the neuronal membrane is at rest, the sodium channels:
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are closed
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What will affect the speed of an action potential?
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the resistance of the membrane
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Where do most action potentials begin?
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at the axon hillock
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