Flashcards in Exam 2: Nervous System I Deck (35)
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Central Nervous System
-brain and spinal cord
-control center
-president
2
Peripheral Nervous System (PNS)
-cranial nerves, spinal nerves and ganglia
-ganglion=group of neuron cell bodies located outside CNS
-workers
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Sensory (afferent) Division
receives information FROM body and transmits it TO CNS for processing
-has both CNS and PNS parts
4
Somatic Sensory
-part of sensory division
-receives sensory information from skin, joints, muscle, special senses (vision, hearing, balance, smell, taste)
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Visceral Sensory
-part of sensory division
-receives sensory info from blood vessels and viscera
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Motor Division
transmits info FROM the CNS To muscles and glands
-has both CNS and PNS parts
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Somatic Motor
-part of motor division
-innervate skeletal muscle
-voluntary
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Autonomic Motor
-part of motor division
-innervates smooth muscle, cardiac muscle, and glands of viscera (organs)
-involuntary
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Neurons
-respond to stimuli and conduct nerve impulses
-primarily amitotic
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Glial Cells
-support and protect neurons
-many more glial cells than neurons
-divide by mitosis
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Cell Body of Neuron
-function: neuron's control center or head
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Nucleus
--houses DNA
-contains nucleolus for protein synthesis
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Chromatophilic substances (Nissl bodies)
-rough ER inside cell body
-function: protein synthesis
-look like darkened clumps within cytoplasm
-no chromatophilic substance in axon hillock
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Dendrites
-short nerve cell process
-function: receive input (incoming nerve impulses)
-send nerve cells to cell body
-neuron can have 1 or many dendrites
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Axon
-long nerve cell process
-function: send output (outgoing nerve impulses
-one axon per neuron
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Axon Hillock
-portion of the cell body from where the axon originates
-no chromatophilic substance here
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Multipolar Neuron
-one axon and many dendrites
-most common
-ex: motor neurons, interneurons
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Bipolar Neuron
-two processes: one axon and one dendrite
-limited in location (rare)
-ex: retina of eye, olfactory neurons in nose
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Unipolar (Pseudounipolar) Neuron
-Single process comes off of the cell body and divides into two branches
-common
-most (not all) sensory neurons
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Sensory (afferent) Neuron
-brings information TO CNS
-either unipolar or bipolar neurons
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Motor (efferent) Neuron
-takes information FROM CNS to other parts of the body
-all are multipolar
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Interneuron
-help coordinate and integrate info between sensory and motor neurons
-located solely in CNS
-"translator/mediator"
-multipolar in form
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Neuron Classification
-by structure or by function
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Satellite Cells
-In PNS
-surround neuron cell bodies in spinal ganglia
-protect the cell bodies
-regulate nutrient exchange and waste removal
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Neurolemmocytes (Schwann Cells)
-myelinate axons in PNS
-myelin is a protective covering around axon that insulates axon and helps produce faster nerve impulses
-can also help regenerate damaged PNS axons
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Astrocytes
-in CNS
-regulate transfer of materials from blood to the brain, help workings of BBB
-helps make blood vessels less leaky
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Blood Brain Barrier
-keeps harmful substances away from brain
-selectively permeable
-bust some needed substances can't pass this barrier either like chemotherapy drugs
28
Astrocytes and the BBB (Parkinsons)
-caused by a decrease of a dopamine
-dopamine can't pass the BBB but a related drug, L-dopa, can.
-Cocaine and methamphetamine pass through and damage BBB
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Oligodendrocytes
-myelinates multipe axons in CNS
-to CNS as neurolemmocytes are to PNS
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Microglia
-phagocytize damaged neurons in CNS
-replicate when there is CNS damage and need to clean up an area
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Ependymal Cells
-line central canal and ventricles of CNS
-help circulate CSF
-central canal and ventricles are spaces within the spinal cord and brain respectively
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Myelination
-process of wrapping an axon with myelin
-myelin insulates axon, produces a faster nerve impulse
-dendrites are not myelinated
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Myelination Procedure in PNS
-Neurolemmocyte wraps around a 1 mm portion of an axon successively
-Cytoplasm and nucleus of neurolemmocyte gets "squeezed" to the outside
-inner successive layers of cell membrane make up the myelin sheath of neurolemocyte
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Neurofibril Nodes (Nodes of Ranvier)
-separate neurolemmocytes
-axon unmyelinated here
-nerve impulse is generated at these nodes
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