1: Basic Organization of the Nervous System Flashcards
Neurons
the major functional unit of the nervous system
Neuroganglia
cells that play an important tole in supporting the neurons
Nerve
a bundle of axons held together by connective tissue
Cell body
integrated information, synthesizes and processes proteins for the neuron
What are 2 other names for a cell body?
- soma
- perikaryon
Dendrites
numerous short processes that receive information from other cells, contain receptors for neurotransmitters
Axon
moves materials from cell body to synaptic terminals, carry action potentials, may be insulated with myelin
Myelin
covering on the axon, not always present
Axon hillock
cone-shaped segment of cell body, part of “trigger zone” where action potentials are generated
Presynaptic termianls
collection of fine branches at distal end of axon
Synapse
specialized junction that allows neurons to communicate with other cells
Myelin functions
- increase speed of conduction
- protection
- insulation
- repair neurons
Axons with larger diameter have ____ conduction velocity
faster
White matter
regions are axons with myelin sheats
White matter in CNS
nerve tracts in spinal cord and brain
White matter in PNS
myelinated axons of peripheral nerves
Gray matter
regions are where the cell bodies and dendrites of neurons collect
Gray matter in CNS
in the cortex and named nuclei of the SC and brain
Gray matter in PNS
cell bodies congregate in regions called ganglia
Polarity of primary sensory neurons
most are unipolar
Polarity of special sensory neurons
most are bipolar
Polarity of motor neurons
most are mulipolar
3 subdivisions of PNS
- somatic
- autonomic
- enteric
Plexuses
network of nerves
Where are cell bodies of lower motor neurons in the SC?
ventral horn
Where are cell bodies of autonomic motor neurons in the SC?
lateral horn
Where are cell bodies of somatic sensory neurons?
dorsal root ganglia and dorsal horn of the SC
What is another name for a mixed spinal nerve?
peripheral nerve
Mixed spinal nerve
bundle of nerve axons
Somatic nervous system
voluntary portion of the nervous system
What are the neurons of the somatic nervous system called?
lower motor neurons
Autonomic nervous system
involuntary portion of the nervous system
What are the 2 divisions of the autonomic nervous system?
- Sympathetic - “fight or flight”
- Parasympathetic - “rest and digest”
Enteric nervous system
control the digestive tract independently of the CNS through local reflexes
What cells produce myelin sheaths?
lemmocytes
