Autonomic Nervous System (ANS) |
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componenets of CNS and PNS that are concerned with the control of visceral functions |
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Nucleus |
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a CNS center with discrete anatomical boundaries |
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Center |
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a group of neuron cell bodies in the CNS that share a common function |
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Tract |
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a bundle of axons within the CNS that share a common origin, destination, and function |
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Column |
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a group of tracts found within a specific region of the spinal cord |
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Pathways |
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Centers and tracts that connect the brain with other organs and systems in the body |
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Ganglia |
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an anatomically distinct collection of sensory and motor neuron cell bodies within the PNS |
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Nerve |
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a bundle of axons in the PNS |
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gray matter |
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nerual tissue dominated by neuron cell bodies |
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white matter |
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neural tissue dominated by myelinated axons |
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neurol cortex |
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a layer of gray matter at the surface of the brain |
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neuron |
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the basic functional unit of the nervous system; a highly specialized cell; a nerve cell |
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sensory neuron |
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a neuron whose axon carries sensory info form the PNS toward the CNS |
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motor neuron |
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a neuron whose axon carries motor commands from the CNS toward effectors in the PNS |
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soma |
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the cell body of a neuron |
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dendrites |
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neruonal processes that are specialized to respond to specific stimuli in the extracellular environment |
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axon |
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a long, slender cytoplasmic process of a neuron; capable of conducting nerve impulses (action potentials) |
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myelin |
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a membranous wrapping, produced by glial cells, that coats axons and increases the speed of action potential propagation |
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neuroglia or glial cells |
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supporting cells that interact with neruons and regulate the extracellular environment, provide defense against pathogens, and perform repairs within neural tissue |
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effector |
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a muscle, gland, or other specialized cell or organ that responds to neural stimulation by altering its activity and producing a specific effect |
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receptor |
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a specialized cell, dendrite, or organ that responds to specific stimuli in the extracellular environment and whose stimulation alters the level of activity in a sensory neuron |
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reflex |
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a rapid, stereotyped response to a specific stimulus |
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somatic |
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pertaining to the control of skeletal muscle acitivity (somatic motor) or sensory info from skeletal muscles, tendons, and joints (somatic sensory) |
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visceral |
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pertaining to the control of functions, such as digestion, circulation, etc (visceral motor) or sensory info from visceral organs (visceral sensory) |
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subconscious |
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pertaining to centers in the brain that operate outside a person's conscious awareness |
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action potential |
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sudden, transient changes in the membrane potential that are propagated along the surface of an axon or sarcolemma |
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Neuroglia in PNS
satellite cells |
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-surround neuron cell bodies in ganglia
-regualte O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia |
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Neuroglia in PNS
schwann cells |
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-surround all axons in PNS
-responsible for myelination of peripheral axons
-participate in repair process after injury |
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Neuroglia in CNS
Oligodendrocytes |
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-myelinated CNS axons
-provide structural framework |
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Neuroglia in CNS
Astrocytes |
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-maintain blood-brain barrier
-provide structural support
-regulate ion, nutrient, and dissolved-gas concentrations
-absorb and recycle neurotransmitters
-form scar tissue after injury |
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Neuroglia in CNS
microglia |
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-remove cell debris, wastes, and pathogens by phagocytosis |
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Neuroglia in CNS
ependymal cells |
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-line ventricles (brain) and central canal (spinal cord)
-assist in producing, circulating, and monitoring cerebrospinal fluid |
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afferent division |
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brings sensory info to CNS |
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efferent division |
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carries motor commands to muscles and glands |
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Anaxonic neruons |
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-small, can't distinguish between axons and dendrites
-found only in CNS and special sense organs |
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Bipolar neruons |
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-one long dendrite that branches at the end and normal axons
-rare but important in relaying sensory info concerning sight, smell, and hearing, un-myelinated |
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Pseudounipolar neurons |
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-cell body situated on one side
- sensory neurons, axons may be myelinated |
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Multipolar neurons |
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-have several dendrites off cell body, and one axons that may have branches (what you think of)
-most common neuron in CNS |
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somatic sensory neruons |
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transmit info about the outside world and our position within it
-receptors: exteroceptors and proprioceptors |
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visceral sensory neursons |
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transmit info about internal conditions and the status of other organ systems
-receptors: interoceptors |
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exteroceptors |
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(outside)
-provide info about external environment in the form of touch, temp, and pressure |
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proprioceptors |
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(one's own)
-monitor position and movement of skeletal muscles and joints |
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interoceptors |
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(inside)
-moniter organ systems and provide sensations of deep pressure, pain, and taste |
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excitability |
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the ability of a plasmalemma to conduct electrical impulses |
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action potential |
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-an electrical impulse
-develops after the plasmalemma is stimulated to a level known as the threshold |
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rate of impulse depends on:
2 |
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1. presence or absense of myelin sheath - myelinated faster
2. the diameter of the axon - larger faster |
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vesicular synapses |
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-AKA chemical synapses
-occurs in one direction only - presnaptic to postsynaptic
-involves the passage of a neruotransmitter substance between cells |
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nonvesicular synapses |
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-AKA electrical synapses, rare
-can occur in either direction
-communication junctions permitting ion flow between cells |
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divergence |
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-spread of info from one neuron to several neurons
-permits the broad distribution of a specific input |
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convergence |
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several neurons synapse on the same postsynaptic neuron |
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serial processing |
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info is relayed in a stepwise sequence, from one neruon to another |
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parallel processing |
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-several neurons are processing the same info at one time
-many different responses occur simultaneously |
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reverberation |
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-collateral axons extend back toward the source of an impulse and further stimulate the presynaptic nerons
-once activated, it will continue to function until synaptic fatigue or inhibitoy stimuli breaks the cycle (walking) |
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