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Somatic Nervous System contains
Sensory neurons for control of skin, muscles, and joints
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Autonomic Nervous System contains
Sympathetic, parasympathetic, and enteric subdivisions that are responsible for involuntary innervation of various organ systems.
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Central Nervous system
brain and spinal cord
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peripheral nervous system
cranial and spinal nerves and receptors
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pathways of the peripheral nervous system
- afferent- bring sensory input to the brain
- efferent- descending, takes input away from brain, innervates muscles.
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Neuron
basic functional cell of the CNS
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Neurons consist of
- cell body aka perikaryon
- dendrites
- a single axon- carries impulses away
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Single axons emerge from where?
May branch to form what?
Diameter?
Most in brain are how big?
Some in spinal cord how big?
- Single axons emerge from cell body at the axon hillock.
- They may branch to form collateral nerves at the point distal to neuron cell body.
- Axon diameter range from 0.2- 20 micrometers
- Most in brain are a few mm long
- In spinal cord can be up to a meter long.
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Stimulation of a dendrite
produce conduction in toward cell body, and then conduction away from the cell body by way of the axon
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Four types of neurons that vary in shape and size.
Unipolar
Unipolar- found only in lower invertebrates
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Four types of neurons that vary in shape and size.
Bipolar
Bipolar- found in the retina, ear, and olfactory mucosa
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Four types of neurons that vary in shape and size.
Pseudounipolar
Pseudounipolar- have one cytoplasmic process that exits the cell and divides into two branches, one serving as dendrite and other serving as axon.
-present in the dorsal root ganglia and cranial ganglion cells, enabling sensory impulses to travel from the dendrite directly to the axon without passing through the cell body.
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Four types of neurons that vary in shape and size.
Multipolar
Multipolar neurons- have multiple dendritic processes but only one axon and constitute the majority of the CNS neurons
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What is gray matter composed of?
neuron cell bodies in the CNS
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What is white matter composed of?
composed of mylinated axons
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Ganglia
regions of concentrated cell bodies within the peripheral nervous system form cranial, spinal, and autonomic ganglia
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