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24 Cards in this Set
- Front
- Back
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neuron
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a nerve cell; the basic building block of the nervous system
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dendrite
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the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
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axon
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the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
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myelin sheath
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a layer of fatty tissue segmentally encasing the fibers of many neurons; enables a vastly greater transmission speed of neural impulses as the impulse hops from one node to the next
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action potential
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a neural impulse; a brief electrical charge that travels down an axon. The action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane
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synapse
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the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the SYNAPTIC GAP
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neurotransmitters
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chemical messages that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse
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threshold
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the level of stimulation required to trigger a neural response
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acetylcholine (ACh)
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a neurotransmitter that enables learning and memory and also triggers muscle contraction
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endorphins
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"morphine within" - natural, opiate-like neurotransmitters linked to pain control and pleasure
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nerves
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neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs
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sensory neurons
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neurons that carry incoming information from the sense receptors to the central nervous system
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motor neurons
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neurons that carry outgoing information from the central nervous system to the muscles and glands
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interneurons
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central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs
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somatic nervous system
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a division of the peripheral nervous system that controls the body's skeletal muscles. Also called the skeletal nervous system
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autonomic nervous system
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the part of the peripheral nervous system that controls the glands and the muscles of the internal organs. Its sympathetic division arouses; its parasympathetic division calms.
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sympathetic nervous system
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the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations
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parasympathetic nervous system
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the division of the autonomic nervous system that calms the body, conserving energy
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reflex
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a simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response
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neural networks
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interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning
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endocrine system
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the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream
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hormones
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chemical messenger, mostly those manufacture by the endocrine glands, that are produced in one tissue and affect another
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adrenal glands
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a pair of endocrine glands just above the kidneys. The adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress
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pituitary gland
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the endocrine system's most influential glad. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands
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