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30 Cards in this Set
- Front
- Back
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What are the two types of glial cells that produce myelin?
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oligodendrocytes (CNS) and Schwann cells (PNS)
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What are the four major types of cells in the CNS and their function?
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Astrocytes: maintain integrity of blood brain barrier, regulate nutrient and dissolved gas concentration; Oligodendrocytes: myelinate CNS axons; Microglia: remove cellular debris & pathogens; Ependymal cells: line brain ventricles and aid in maintenance of CSF
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What are the two major types of cells in the PNS and their function?
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Schwann cells: myelinate axons of the PNS; Satellite cells: surround the neuron cell bodies in the ganglia
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Impulses, known as ___________, travel the length of the axon and invade the nerve terminal, thereby causing the release of neurotransmitter into the synapse
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action potentials
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A typical resting membrane potential is ________.
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-70 mV (which means the inside of the neuron is more negative than the outside)
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What causes the potential difference of a cell at rest? How is this difference maintained?
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the difference is caused by selective ionic permeability of the neuronal membrane to K+ (and impermeability to Na+), so K+ diffuses down its concentration gradient; is maintained by the active transport of the Na+/K+ pump
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The concentration of K+ is higher _______ the neuron; the concentration of Na+ is higher _______ the neuron.
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inside; outside
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The Na+/K+ pump uses ATP energy to transport ___ Na+ out for every ____ K+ it transports into the cell.
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3 Na+ out; 2 K+ in
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How is an action potential generated?
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if the cell becomes sufficiently excited or depolarized (i.e., the inside of the cell becomes less negative)
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The ______________________ is the level at which an action potential is initiated.
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minimum threshold potential (usually around -50 mV)
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Describe what happens during an action potential.
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Begins when voltage-gated Na+ channels open in response to depolarization, allowing Na+ to rush down its electrochemical gradient INTO the cell (bc concentration of Na+ is usually lower inside the cell than outside), causing a rapid further depolarization of that segment of the cell. The voltage-gated Na+ channels then close,and voltage-gated K+ channels open, allowing K+ to rush OUT down its gradient (because concentration of K+ is usually lower OUTSIDE the cell). This returns the cell to a more negative potential, known as repolarization. If the neuron shoots past the resting potential and becomes even more negative inside than normal, it is called HYPERpolarization.
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Immediately after an action potential, it may be very difficult or impossible to initiate another action potential; this period is called the _________________.
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refractory period
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What factors increase the speed at which action potentials are propagated?
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The greater the diameter of the axon and the more heavily it is myelinated, the faster the impulses will travel.
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Describes what happens at the synapse.
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When the action potential arrives at the nerve terminal and depolarizes it, the synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synapse. The neurotransmitter diffuses across the synapse and acts on receptor proteins embedded in the postsynaptic membrane. This will lead to depolarization of the postsynaptic cell and consequent firing of an action potential.
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Neurons that carry sensory information to the brain or spinal cord are called _______ neurons.
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afferent (think AFFerent as in relaying "AFFects" of stimulus or "AFFecting" the brain)
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Neurons that carry motor commands from the brain or spinal cord to various parts of the body are called ______ neurons.
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efferent (think "e" as in "exit"ing the brain and spinal cord)
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Sensory information enters the spinal cord through the _____ horn; the cell bodies of these sensory neurons are located in the _____________.
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dorsal; dorsal root ganglia
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All motor information exits the spinal cord through the _____ horn.
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ventral
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What are the two primary divisions of the PNS?
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autonomic (ANS) and somatic (SNS)
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What is the role of the SNS?
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innervates skeletal muscle and is responsible for VoLunTarY movement.
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What is the role of the ANS?
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regulation of the body's internal environment; involuntary nervous system; innervates cardiac and smooth muscle
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What are the two divisions of the ANS?
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1. Sympathetic: responsible for the "flight or fight" responses; inc blood pressure & heart rate, inc blood flow to skeletal muscles, and decreases gut motility; uses norepinephrine as its primary neurotransmitter. and 2. Parasympathetic: acts to conserve energy and restore body to resting levels after exertion ("rest and digest"); lowers heart rate and increases gut motility; uses acetylcholine as primary neurotransmitter
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One very important parasympathetic nerve that innervates many of the thoracic and abdominal viscera is the _____________, which uses acetylcholine as its primary neurotransmitter.
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vagus nerve
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The thick, opaque layer of the eye is the __________ (or white of the eye).
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sclera
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Beneath the sclera is the ____________, which helps to supply the retina with blood.
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choroid layer
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The innermost layer of the eye is the ______, which contains the photoreceptors that sense light.
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retina
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light travels through an opening called the ______, whose diameter is controlled by the pigmented, muscular _____.
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pupil; iris
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The _____ focuses the image onto the retina and is controlled by the _______ muscles.
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lens; ciliary
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What are the two main types of photoreceptors?
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cones (sensitive to color) and rods (important for night vision)
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By increasing the intensity of the stimulus, the action potential will:
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increase in frequency
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