Module 7 Vocabulary
myelin sheath
a fatty wrapping which speeds up the conduction of the action potential down the axon
potential difference
a measure of the charge difference across the cell membrane
as you read this question, cells in your eyes are sending information to your brain, which your brain uses to form an image of the words that you read. Is this information being sent along afferent (towards the CNS) or efferent nerves (away from the CNS)?
afferent nerves
collateral axons
axons that split off the main branch
oligodendrocyte
bings together and insulates CNS neurons
nerves
bundles of neuron axons and their coverings which are found outside the CNS
presynaptic neuron
carries signals to the synapse
soma
cell body that houses the nucleus
unit of a neuron
cell body, axons, and dendrites
ganglia
collections of neuron cell bodies that are found outside the CNS
peripheral nervous system (PNS)
composed of all the parts of the nervous system (PNS) that are not in the central nervous system (CNS)
central nervous system (CNS)
composed of the brain and the spinal cord
PNS
consists of nerves and ganglia
epineurium
covering of a nerve
endoneurium
covering of an axon
the strength of the stimulus
determines the frequency of the action potential
sympathetic division
division of the ANS that generally prepares the body for increased energy expenditure (the fight-or-flight division)
parasympathetic division
division of the ANS that regulates resting and nutrition related functions such as digestion, defecation, and urination
what are the differences between a sensory nerve, a motor nerve, and a mixed nerve? What is the most common kind of nerve in the body?
sensory neurons, which make up sensory nerves, can only send incoming messages to the CNS. Motor neurons, which make up motor nerves, can only send outgoing messages from the CNS to muscles or glans when a nerve carries both neurons, it is a mixed nerve. Most nerves in the body are mixed nerves.
nerves in the human body are either
sensory, motor, or mixed. The most common type is the mixed nerve
presynaptic terminals
terminal boutons or axon terminals
excitability
the ability to undergo an action potential in response to a stimulus
perineurium
the covering of a fascicle
oscillating neuron
the message stimulates itself
depolarization
the potential difference basically become zero
refractory period
the time when no action potential can be generated on the neuron because one in already in progress
inhibitory synapse
this type of synapse makes up the majority of neuron to neuron synapses in the body
resting potential
where the axon is not carrying any signal
name the 6 types of neuroglia and their functions
-oligodendrocytes: binds together and insulates CNS neurons -schwann cell: insulates PNS neurons -microglia: fight infection with phagocytosis -astrocyte: form the blood-brain barrier -ciliated ependymal cells: move cerebrospinal fluid -non-ciliated ependymal cells: secrete cerebrospinal fluid
somatic motor nervous system
PNS neurons that transmit action potentials from the CNS to the skeletal muscles
autonomic nervous system
PNS neurons that transmit action potentials from the CNS to smooth muscles, cardiac muscles, and glands
an axon is covered by several schwann cells. If it is severed, will it definitely heal? Why or why not?
No, not definitely. Unless the branching axon is pointing in the general direction of the severed end, it will not be able to heal
association neuron
a neuron that conducts action potentials from one neurons to another neuron within the CNS
multipolar neuron
a neuron with many processes: several dendrites but only one axon
unipolar neuron
a neuron with only one process and the cell body is suspended from that process
bipolar neuron
a neuron with two processes: an axon and a dendrite
local potential
a small change in the potential difference that just dies out because the stimulus that produced it was subthreshold
when you are digesting food, smooth muscles contract your stomach. Is this controlled by the afferent division of the PNS? You can be even more specific than that. What would be the most specific way to describe the nerves involved in this situation?
efferent neurons; autonomic division
microglia
fight infection with phagocytosis
astrocyte
form the blood-brain barrier
nodes of Ranvier
gaps in the myelin sheath
schwann cell
insulates PNS neurons
an axon is covered by an oligodendrocyte. Is it part of the CNS or the PNS? Will it regenerate a new axon, if severed?
it is part of the CNS. It is not able to regenerate an axon
convergent
many inputs lead to one limited output
spinal nerves
nerves that originate from the spinal cord (part of the PNS)
cranial nerves
nerves that originates from the brain (part of the CNS)
oligodendrocytes
neuroglia in the CNS
schwann cells
neuroglia in the PNS
afferent neurons
neurons that transmit action potentials from the sensory organs to the CNS (also called the sensory division). It carries signals from the sensory neurons: the tongue, ears, nose, etc.
efferent neurons
neurons that transmit action potentials to the effector organs (a.k.a. the motor division) It carries signals from the CNS to the effector organs
divergent
one message gets spread to different parts of the body
ependymal cells
one of the 6 types of neuroglia. There are 2 types of ependymal cells: non-ciliated ependymal cells which secrete cerebrospinal fluid and ciliated ependymal cells which move that cerebrospinal fluid