Intro to nervous system Flashcards
Clusters of neuronal cell bodies are called ______.
Nerve nuclei
Organized bundles of neuronal processes are termed ________.
Fiber tracts
Groups of peripheral nerve cell bodies are termed ______.
Ganglia
What defines a ganglion cell?
Any neuron whose soma is situated int he PNS.
What are the divisions of the 31 vertebrae?
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
What vertebrae control the upper limbs?
C5 - T1
What vertebrae control the lower limbs?
L2 - S3
Are there synapses in sensory ganglia?
No
Describe sensory (afferent) neuron structure.
Single unipolar cell body extends a process out to the tissues for sensory reception and a central process inward to the dorsal portion of the spinal cord or brain stem.
Sensory axons in a spinal nerve pass to the spinal cord through a _________, and the corresponding nerve cell bodies for a ______________ for the nerve.
dorsal (posterior) root, sensory dorsal root ganglion
Are sensory neurons unipolar or multipolar?
Unipolar
Are motor neurons unipolar or multipolar?
Multipolar
Describe motor neuron structure.
Multipolar motor neurons in VENTRAL regions of the spinal cord extend their axons outward through spinal and cranial nerves. Distance from CNS to the peripheral target is bridged by one or two neurons depending on the tissue being innervated.
Motor neurons leave the spinal cord through the _________.
Ventral (anterior) root of the nerve
What is the structure of somatic innervation?
Direct single-neuron pathway to skin and deeper musculoskeletal tissues.
What is the structure of autonomic innervation?
Indirect two-neuron pathway to cardiac muscle, smooth muscle, and glands, etc.
First neuron is in the CNS. It synapses in the PNS on a motor ganglion cell.
The sympathetic nervous system is also referred to as what?
Thoracolumbar division (axons leave at T1 - L2)
The parasympathetic nervous system is also referred to as what?
Craniosacral division (axons leave at S2 - S4)
What are GSE fibers?
General Somatic Efferent fibers: motor outflow to VOLUNTARY STRIATED muscles. They are large multipolar neurons in the ventral portion of the spinal cord. Single neuron pathway
What are GSA fibers?
General Somatic Afferent fibers which carry sensory inflow from non-visceral tissues. Single neuron pathway
What is exteroception?
Perception of the external environment, conveyed from sensory receptors int the skin. Related to temperature, touch, pressure, and pain.. These reach consciousness and are well localized.
What is proprioception?
Perception of self from stretch, acceleration, and other receptors in muscles, joints, and tendons. Can reach consciousness if desired.
What are GVE fibers?
General Visceral Efferent: fibers carry motor outflow to cardiac muscle, involuntary smooth muscle, and glands. Two neuron pathway originating with multipolar cells in the ventral spinal cord. Called “pre-ganglionic because they synapse with motor ganglion cells in the periphery. After the ganglion = post-ganglionic.
Describe the structure of the sympathetic motor pathway.
Preganglionic neurons leave through T1-L2 via ventral roots. These bundles are called “white” ramus communicans. Immediately outside of the spinal cord they reach a sympathetic chain/trunk of motor ganglion cells that serve ALL body levels.
All ganglion cells in the chain receive synaptic input from pre-ganglionic neurons in the ________ spinal cord.
Throacolumbar