central nervous system (CNS)
consists of brain and spinal cord, enclosed within the cranial vault and vertebrae
peripheral nervous system (PNS)
composed of cranial nerves and spinal nerves
also can be divided into somatic and autonomic nervous systems
cranial nerves
project from the brain and pass through foramina in the skull
spinal nerves
project from the spinal cord and pass through intervertebral foramina of the vertebrae
afferent
pathways that carry sensory impulses toward the CNS
efferent
descending pathways carrying sensory impulses from the CNS to effector organs
somatic nervous system
consist of motor and sensory pathways regulating voluntary motor control of skeletal muscle
autonomic nervous system
consists of motor and sensory components and is involved with regulation of the body's internal
environment through involuntary control of organ systems
-can be further divided into sympathetic and parasympathetic
microtubules
made of protein and believed to be involved in transport of cellular products
neuroglial cells
found in the CNS and PNS and can provide structural support and nutrition for neurons, remove debris,
increase speed of nerve impulses, and play a role in memory
Nissl substances
consist of ER and ribosomes and are involved in protein synthesis
nuclei
dense, packed cell bodies in the CNS
ganglia
groups of cells bodies in the PNS
,McCance Huether Pathophysiology Test 1
dendrites
extensions that carry nerve impulses toward the cell body
dendritic zone
the receptive portion of a neuron that receives a stimulus and continues further conduction
axons
long, conductive projections from the cell body that carry nerve impulses away from the cell body
axon hillock
the cone-shaped, organelle-free area where the axon leaves the cell body
fascicles
bundles of axons in large nerves
myelin
an insulating substance made of a segmented layer of lipid material
endoneurium
a delicate connective tissue around each axon in the PNS
nodes of Ranvier
interruptions in the neurilemma and myelin sheath
saltatory conduction
process by which ions can flow between segments rather than along the entire length of the membrane,
resulting in increased velocity of neuronal conduction
divergence
ability of branching axons to influence many different neurons
convergence
branches of numerous neurons converging on and influencing one or a few nuerons
larger
_________axons transmit impulses at a faster rate
unipolar
neurons have one process that branches shortly after leaving the cell body.
pseudounipolar
,McCance Huether Pathophysiology Test 1
neurons that have one process that has its dendritic portion extending away from the CNS and its axon
portion projecting into the CNS
-typical of sensory neurons in cranial and spinal nerves
bipolar
neurons that have two distinct processes arising from the cell body; example: neuron connecting rod
and cone cells of the retina
multipolar
neurons that are the most common and have multiple dendrites and a single axon; example: most
motor neurons
sensory
neurons that carry im,pulses from peripheral sensory receptors to the CNS
interneurons
transmit impulses from neuron to neuron and are also involved in cognitive function
motor
neurons that transmit impulses away from the CNS to an effector organ
neuroglia
most numerous type of CNS cell
astrocyte
a neuroglial cell that fills spaces between neurons and surrounds blood vessels in the CNS
oligodendrocyte
a neuroglial cell that functions to deposit myelin within the CNS; the CNS counterpart of the Schwann
cells
ependymal
neuroglial cell that lines the CSF-filled cavities in the CNS
microglia
remove debris through phagocytosis in the CNS
Schwann cell
a glial cell that wraps around and covers axons in the PNS. Forms and maintains the myelin sheath
wallerian degeneration
the sequence of events that occur when an axon is severed
, McCance Huether Pathophysiology Test 1
synapse
region between adjacent neurons
presynaptic
neurons that relay impulses toward the synapse
postsynaptic
neurons that relay impulses away from the synapse
action potential
An ______ _______ in the presynaptic neuron causes the synaptic vesicles to release their
neurotransmitters through the plasma membrane into the synaptic cleft
neurotransmitter
A ________ is normally stored on one side of a synaptic cleft, and its receptors are on the other side
cannabinoid
transmitters that are released from postsynaptic neurons that modulate neurotransmitter release from
presynaptic neurons
summation
the number and frequency of potentials the postsynaptic neuron receives
temporal summation
the effects of successive, rapid impulses received from a single neuron on the same synapse
spatial summation
the combined effects of impulses from a number of neurons on a single synapse at the same time
facilitation
the effect of excitatory postsynaptic potentials on the plasma membrane potential
brainstem
made up of the midbrain, medulla oblongata, and the pons
reticular formation
a large network of connective tissue nuclei within the brainstem that regulate vital reflexes. Essential for
maintaining wakefulness
reticular activating system
reticular formation + cerebral cortex
plasticity