Exam II | Nervous System General Organization & Cytology Flashcards
At what level of the spine does the spinal cord end?
L1-L2
At what level of the spine does the dura mater end?
mid-sacrum
What is the filum terminale? Where does it begin and end?
- a specialized portion of the pia mater
- filum terminale internum begins at medullary cone and extends through dural sac
- filum terminale externum extends from bottom of dural sac to coccyx
What does the white matter of the cord primarily consist of? Gray matter?
- white consists of myelinated axons
- gray consists of cell bodies
What is the difference between tracts and nerves?
tracts are axon bundles in the CNS; nerves are axon bundles in the PNS
What are the buttons or ‘boutons’ of the neuron?
axon terminals
What are bipolar neurons, and where are they located?
- sensory motor neurons
- present in the eye and other specialized sensory structures
- e.g hair cells of the cochlea
What are pseudo-unipolar neurons, and where are they located?
- sensory motor neurons
- free nerve endings (e.g. dendrites extend up into dermis) that act as the receptor
- present in the somatosensory system
What are multipolar neurons?
motor neurons with a large number of dendrites
What are primary or alpha motor neurons, and where do they extend from?
- aka lower motor neuron (LMN) or last neuron
- the neuron that carries the final motor signal and is in contact with the effector (muscle)
- extends from ventral horn of cord to effector
What are primary or alpha sensory neurons?
- initial neuron in pathway the generates action potential
- carries initial sensory signal
- may also be the receptor cell (e.g. free nerve ending)
- or it may receive signals from a specialized receptor (such as a Merkel’s disk or corpuscle)
Where is the cell body of the afferent nerve?
DRG or cranial nuclei
Where is the cell body of the efferent nerve?
the ventral horn of the cord or cranial nuclei
What does the term “somatic” refer to?
- motor neurons of the PNS
- or to all motor and sensory neurons of the PNS that are not autonomic
Significance of dendritic spines
critical for interneuronal communication or LTP (learning, memory, association, etc.)
How many neurons and synapses form a disynaptic reflex arc?
- 3 neurons (efferent, interneuron, afferent)
- 2 synapses
What is the difference between nervous system ganglia and nuclei?
- Ganglia are in the PNS, nuclei are in the CNS
- exception is basal nuclei
How does a sensory ganglion differ from an autonomic ganglion?
autonomic ganglion have synapses, sensory ganglion do not
What is the difference between a motor unit and a myotome?
- a motor unit is a motor NEURON and all the muscle FIBERS innervated by it
- a myotome is a range of MUSCLES that are generally innervated by MORE THAN ONE spinal NERVE
What is the neurotransmitter and receptor at the neuromuscular junction?
Ach; nicotinic