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50 Cards in this Set
- Front
- Back
A change in a membrane potential from +30 mV to -70 mV is an example of
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repolarization
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A threshold potential is
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the point at which there is an explosive increase in Na+ or Ca2+ permeability
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Graded potentials
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are local changes in membrane potential that occur in varying degrees of magnitude, and serve as short-distance signals
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The rising phase of the action potential is due to
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sodium influx
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Myelinated axons conduct impulses much faster because
A. The myelin insulates the axon B. Channels only have to open at the nodes C. Voltage is not lost along myelinated areas D. Saltatory conduction occurs E. All of these |
E. All of these
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At the peak of an action potential:
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The concentration gradient for K+ tends to move this ion out of the cell, and K+ permeability greatly increases
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The absolute refractory period
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refers to a period when the membrane cannot undergo another action potential and places an upper limit on the frequency with which a neuron can conduct action potentials
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Sequence the following events correctly.
1. Neurotransmitter diffuses across cleft 2. Calcium induces exocytosis of neurotransmitter 3. Permeability of postsynaptic membrane altered 4. Ion channels open 5. Neurotransmitter binds to receptor |
2,1,5,4,3
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In divergence
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An axon branches to synapse with many cells so that activity in one neuron influences the excitability of many other cells
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The nodes of Ranvier are
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breaks in the myelin covering
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Drugs may influence synaptic transmission by
A. altering the formation of neurotransmitters B. blocking neurotransmitter reuptake C. blocking receptors D. blocking channels E. all of these |
E. all of these
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The normal sequence of structures activated for signal transmission and response in the body is
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receptor->afferent neuron->interneuron->efferent neuron->effector
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Afferent neurons
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transmit messages to the spinal cord
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Which type of cell lines the ventricles of the brain?
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ependymal cells
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Which of the following is not a function of astrocytes?
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Line the internal cavities of the brain and spinal cord
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Cerebrospinal fluid
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is formed by the choroid plexus
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The arachnoid mater is
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a delicate, richly vascularized meningeal layer that is "cobwebby" in appearance
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The region of the brain that is the oldest in evolutionary development is the
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brain stem
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The sense of body position is
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proprioception
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Most of the cranial nerves originate from the
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brain stem
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The peripheral nervous system includes
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24 cranial nerves
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Which of the following is a monosynaptic reflex?
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stretch reflex
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Receptors
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exist that are specific for every modality in the environment, and when stimulated enough may cause Na+ channels in the afferent neuron membrane to open
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Receptor potentials
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are graded potentials
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Polymodal nociceptors
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activate the slow pain pathway
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The smaller the receptive fields in a region, the
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greater the density of receptors in the region and greater the acuity in the region
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Endorphins and enkephalins
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are endogenous morphine-like substances, important in the body's natural analgesic system
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Select the incorrect statement about slow pain
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It is carried by large, myelinated A-delta fibers
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The retina
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contains the photoreceptors
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During accommodation for near vision, the
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lens becomes stronger
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The blind spot
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is the point on the retina at which the optic nerve leaves and blood vessels pass through
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Which of the following is the proper sequence of retinal processing?
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rods and cones - bipolar cells - ganglion cells
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Vitamin A deficiency causes
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poor night vision
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The pitch of sound
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is determined by the frequency of vibrations of air molecules
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Fluid movement in the cochlea causes
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displacement of the round window, which dissipates pressure
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The auditory cortex is in the ________ lobe of the cerebral cortex
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temporal
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Actual conversion of sound vibrations to nerve impulses occurs in the
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cochlea
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Sour tastes represents stimuli caused by
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acids
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Olfactory receptors
A. are specialized endings of afferent neurons, not separate cells B. when stimulated send impulses both to the limbic system for coordination between smell and behavior and to the thalamus and cortex for perception of smell C. are replaced about every two months D. are located in the olfactory mucosa E. all of these |
E. all of these
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The structure associated with pheromonal reception is
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vomeronasal organ
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The autonomic nervous system is
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the involuntary branch of the peripheral nervous system's efferent division
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Which is not a characteristic of sympathetic pathways?
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Preganglionic fibers release norepinepherine
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Postganglionic autonomic fibers
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have numerous varicosities that simultaneously release neurotransmitter over a large area of the innervated organ rather than on single cells
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Select the incorrect statement about the parasympathetic nervous system
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It inhibits all cardiac muscle and smooth muscle
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Sympathetic stimulation _____ heart rate and ______ the motility in the digestive tract
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increases; decreases
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Nicotinic receptors
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respond to ACH released from sympathetic and parasympathetic preganglionic fibers
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Acetylcholinesterase
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inactivates a neurotransmitter
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Which type of receptor binds to norepinephrine on cardiac muscle, thus increasing cardiac activity?
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beta-1
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Select the correct statement about the neuromuscular junction
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it is always excitatory
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What would occur is ACh was not removed from the nicotinic receptors on skeletal muscle cells?
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The cell would remain contracted until fatigued, and sodium would continue to move into the cell causing excitation
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