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22 Cards in this Set
- Front
- Back
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What are the 2 main divisions of the nervous system? |
Central Nervous System/CNS: brain and spinal cord Peripheral Nervous System/PNS: nerves and ganglia |
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What is another name for a nerve cell? |
neuron |
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What are the properties of neurons? |
Excitability (irritability) Conductivity Secretion: can release chemical messengers, or neurotransmitters (ex: acetylcholine) |
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What are the functional classes of neurons? |
sensory (afferent) neurons - detect stimuli interneurons (association neurons) motor (efferent) neurons - send signals to muscles to provide response |
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Describe the structure of a neuron... |
neurosoma (soma or cell body) - control center nissl bodies - compartmentalized rough ER dendrites - receive signals axon - sends action potentials |
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Describe the varieties of neurons... |
multipolar: many dendrites, one axon. most abundant in our body bipolar: one dendrite, one axon unipolar: no dendrites, one axon anaxonic: many dendrites, no axon |
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What are the glia associated with the CNS? |
oligodendrocytes (myelinate to assist conduction) ependymal cells microglia astrocytes |
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What are the glia associated with the PNS? |
schwann cells satellite cells |
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What is the function of myelin? |
helps speed the transmission of the message |
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Describe myelin... |
similar to insulation on a wire. speeds transmission of message. oligodendrocytes make fatty white matter of CNS. Nodes of ranvier: fiber segments with gaps in myelin |
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What are nodes of ranvier? |
fiber segments with gaps in myelin |
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What is the neurilemma? |
the outermost coiled layer of a Schwann cell |
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Describe nerve repair... |
the PNS can repair itself if damaged, the CNS cannot. |
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Do fibers need myelin? |
No. Sometimes fast reaction to a stimulus is not necessary. |
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Describe signal conduction... |
depends on 2 factors: diameter of fiber (larger are faster), and presence of myelin (myelinated are faster) |
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Describe nerve regeneration... |
if the cell body remains intact, cut nerve fibers can regenerate in the PNS. Schwann cells secrete nerve growth factors. CNS neurons cannot regenerate. |
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What is a synapse? |
meeting point of neuron and other cell |
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What are the types of synapses? |
axodendritic (axon to dendrite) axosomatic (axon to soma) axoaxonic (axon to axon) |
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Describe chemical synapses... |
presynaptic neuron releases neurotransmitter to postsynaptic cell |
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What is a neurotransmitter? |
messenger molecule. some are excitatory, some are inhibatory |
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Describe electrical synapses... |
adjacent cells joined by gap juntions. ions diffuse from cell to cell. |
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Describe some neural tube defects (NTDs)... |
spina bifida: vertebrae fail to enclose spinal cord. spina bifida occulta (1- a few vertebra, no functional problems), spina bifida cystica (more severe, sac protrudes from spine) microcephaly: small brain anencephaly: no brain |
