Nervous System Flashcards
what does the abbreviation “CNS” stand for
central nervous system
what does the CNS consist of
billions of neurons in the brain and spinal cord
what are tracts
bundles of axons in the CNS
axons carry impulses in only one direction in the CNS.
what are those directions and the proper terms for them
ascending: sensory impulses traveling to the brain from the spinal cord
*to the brain
descending: motor impulses traveling from the brain to the spinal cord
*to the spinal cord
what does the abbreviation “PNS” stand for
peripheral nervous system
what does the PNS consist of
all the nerves and receptors outside of the brain and spinal cord
what are nerves
bundles of axons in the PNS
axons carry impulses in only one direction in the PNS.
what are those directions and the proper terms for them
afferent: sensory impulse traveling towards the CNS from PNS
*towards spine
efferent: motor impulses traveling from the CNS to the PNS
*towards receptors
what does autonomic efferent mean
involuntary impulses to smooth muscle, glands, and cardiac muscle
what does somatic efferent mean
voluntary major impulses to skeletal muscle
in the PNS there are sensory (________) and motor (________) neurons
afferent; efferent
in the CNS there are sensory (_____) and motor (_____) neurons
ascending; descending
what are the functions of neurons
sensory, motor, and integrative pathways
there are cranial nerves (enter/exit brain) and spinal nerves (enter/exit) spinal cord
are these nerve part of the CNS or PNS
PNS
what are the two types of cells in the nervous system
neurons and neuroglia (glial cells)
what is the general function of a neuron
to carry impulses across the body in response to stimuli
what is the general function of neuroglia
to support the neurons
what are the general functions of astrocytes
serve as a blood-brain barrier
potassium/sodium/carbon dioxide balance
metabolism of neurotransmitters
repair of damaged areas in CNS
neuronal connections during development
what is the general function of microglia
phagocytes that digest debris
what is the general function of ependymal cells
ciliated cells that line spaces in the brain and aid with movement of cerebrospinal fluid
what is the general function of oligodendrocytes
they make the myelin sheath in the CNS
what is a myelin sheath and what is its purpose
a phospholipid covering around axons of neurons in the CNS and PNS
they aid in conduction of electrical impulses and isolation of the neuron
what are satellite cells
cells in the PNS that support the neurons in ganglia
what are ganglia
nerve cell clusters in the PNS
what is a ganglion
group of neural cell bodies in the PNS
what are Schwann cells
cells that make the myelin sheath in the PNS
what is another name for Schwann cells
neurolemmocytes
satellite cells are analogous to which cells in the CNS
astrocytes
Schwann cells are analogous to which cells in the CNS
oligodendrocytes
why are neurtubules important in a neuron
they provide internal support to the neuron
what is the purpose of the myelin sheath
insulation
make impulses faster
save ATP
which cell makes the myelin sheath in the CNS
oligodendrocytes
which cell makes the myelin sheath in the PNS
Schwann cells
are all neurons in the PNS and CNS myelinated
no there are some unmyelinated neurons as well
does the CNS contain neurolemma
no
does the PNS contain neurolemma
yes
what is neurolemma
the nucleated cytoplasmic (outer) layer of the Schwann cells
unmyelinated axons conduct impulses ________ than myelinated ones
a. faster
b. slower
slower
how are neurons classified
by structure and function
what are the types of structures neurons can have in the nervous system
mulitpolar - many extensions
bipolar - 2 extensions
unipolar - single extension
what does it mean for a neuron to be classified structurally
it is based on the number of extensions on the soma of a neuron
what does it mean for a neuron to be classified functionally
based on the type of impulse that is carried by the neuron
what are the types of functional names a neuron can have
sensory
motor
association or integrative
define resting membrane potential
the difference in voltage between the inside and outside
what is the resting potential voltage in a neuron
-70 mV
why is the inside negatively charged relative to the outside of the membrane
there are many large proteins that are anions with a negative charge
what is the function of the Na+/K+ pump
to maintain resting potential
it pumps out potassium and takes in sodium
does the Na+/K+ pump require ATP
yes
what does the somatic nervous system do
carries sensory information from the PNS to the brain then to the skeletal muscles
does the somatic nervous system innervate with the skeletal system
yes
what does the autonomic nervous system do
involuntary movement of impulses
does the autonomic nervous system innervate with cardiac and smooth muscle
yes
what is the enteric nervous system
nervous system of the gastrointestinal tract that can work independently from the somatic and autonomic
can the enteric nervous system be influenced by the autonomic nervous system
yes
what is depolarization
reversing the charge
*negative to positive
what is repolarization
reversing the reverse charge and putting it back to normal
*positive back to negative
what happens to the membrane during depolarization
the membrane becomes more permeable to Na+ (sodium)
what happens to the membrane during repolarization
the membrane potential is reestablished
how is depolarization caused
Na+ rushes into the cell bringing a positive charge into the cell so the membrane becomes more positive
what are voltage sensitive gates
channels that need to meet a threshold in order to function
what is the threshold for voltage sensitive channels
-55mV
textbook: -60mV
how does the cell reestablish membrane potential
K+ is positive and it leaves the cell
what is hyperpolarization
membrane potential that becomes more negative than the resting membrane potential
what is the refractory period
the time at which you can’t send action potentials
in an action potential, when does the refractory period occur
during depolarization
what is the all or none response
cells will excite to its greatest capacity through each action potential
what is saltatory conduction
action potentials jumping from node to node
what are the nodes in between the myelin sheaths called in saltatory conduction
nodes of Ranvier
in myelinated axons the action potential only occurs at the nodes of _______. the myelin insulates the rest of the axon
Ranvier
what are the advantages of saltatory conduction
fast
saves ATP
what do fast nerves look like
large diameter with myelin
speed of action potentials increases with _______
temperature
what are the different types of nerve fibers
A fibers - large diameter
B fibers - contain myeline
C fibers - no myelin
what is continuous conduction
slow action potentials that occur in unmyelinated neurons
what is a presynaptic neuron
the neuron before the synapse
what is a postsynaptic neuron
the neuron after the synapse
what is a chemically gated channel
a channel where the opening of said channel is caused by a chemical binding to a receptor
what is a voltage gated channel
a channel where the opening of said channel is caused by a change in voltage
what does ionotropic mean
neurotransmitters that bind to a receptor that also serves as a channel
what does metabotropic mean
neurotransmitters binds to a receptor that triggers the opening of a channel
what is an inhibitory postsynaptic potential
the possibility for a neurotransmitter to bind to its receptor and not move it closer to the threshold
what is a graded potential
the neurotransmitters binding to their receptors causing a local change
what is an excitatory postsynaptic potential
a graded potential that is moving the voltage towards the threshold
what is glutamine
the most common excitatory neurotransmitter
what is GABA
the most common inhibitory neurotransmitter
what fires the action potential when the threshold is reached
the axon hillock
what is a direct electrical synapse
a gap junction in cardiac muscle
what is a chemical synapse
where an impulse can only travel in one direction
list the events that occur at a synapse
- action potential is fired
- action potential reaches the axon end bulb and triggers calcium to flow into the bulb through voltage sensitive calcium channels
- calcium influx triggers the movement of vesicles with neurotransmitters towards the membrane of the axon terminal
- the neurotransmitter is released by exocytosis and diffuses across the synaptic cleft
- the neurotransmitter attaches to a receptor on the postsynaptic membrane and causes a change in the resting membrane potential
is the neurotransmitter in the nervous system always acetylcholine
no
what is the purpose of having numerous neurotransmitters in the body
for different functions/reactions needed in response to different stimuli
what changes on the postsynaptic membrane can be caused by neurotransmitters
the change in voltage
the neurotransmitter acetylcholine causes _____ influx on the skeletal muscle membrane. the ____ influx depolarizes the motor end plate and initiates the ________
Na+
Na+
action potential
some neurotransmitters caused the membrane potential of the postsynaptic cell to move closer to the threshold.
what is another words for it moving closer to the threshold
excitatory
some neurotransmitters caused the membrane potential of the postsynaptic cell to move away from the threshold.
what is another word for it moving away from the threshold
inhibitory
is acetylcholine release at the neuromuscular junction always excitatory or inhibitory
excitatory
what is a converging circuit
a lot of presynaptic neurons and one postsynaptic neuron
do excitatory neurotransmitters depolarize or repolarize the membrane
depolarize
do inhibitory neurotransmitters depolarize or hyperpolarize the membrane
hyperpolarize
excitatory neurotransmitters cause the inside of the cell to move closer to the threshold of ______
-55mV
what determines if an action potential is generated
the axon hillock summates all of the information from the neurons synapses and determines if the action potential will be generated
what is the trigger zone
zone of which if the sum reaches the potential of -55mV or higher causing an action potential
what is temporal summation
repeated impulses over time
what is spatial summation
several neurons firing at once
what is summation
the process that determines whether or not an action potential will be generated by the combined effects of excitatory and inhibitory signals
what is facilitation
axon hillock moving closer to the threshold in a neuron
what are examples of neurotransmitters
acetylcholine
amino acids glutamate and GABA
noradrenaline
norepinephrine
dopamine
serotonin
nitric oxide
endorphins
enkephalins
- neurotransmitter at the neuromuscular junction (excitatory)
- neurotransmitter in the autonomic nervous system
- broken down by cholinesterase
- nitocine stimulates these receptors
what type of neurotransmitter do these traits define
acetylcholine
- most common inhibitory neurotransmitter in the brain
1.A. valium increases these levels - is an amino acid
what type of neurotransmitter do these traits define
GABA
- most common excitatory neurotransmitter in the brain
- is an amino acid
what type of neurotransmitter do these traits define
glutamine
- can also be norepinephrine
- neurotransmitter in the autonomic nervous system
- important neurotransmitter in the brain for arousal from sleep
what type of neurotransmitter do these traits define
noradrenaline
- muscle control
- creates the “high” of certain drugs and plays a role in addiction
- role in memory
what type of neurotransmitter do these traits define
dopamine
- role in sleep, mood, and appetite
- important neurotransmitter in the GI tract
what type of neurotransmitter do these traits define
serotonin
- gas
- smooth muscle relaxer
what type of neurotransmitter do these traits define
nitric oxide
- neuropeptides
- may be released with neurotransmitters
- affect the function of neurotransmitters
- natural pain killers
what type of neurotransmitters do these traits define
endorphins and enkephalins
what is the type of nervous system that innervates smooth muscle, glands, and cardiac muscle
autonomic nervous system
what tissues are innervated by the somatic nervous system
skeletal muscle
what are the CNS neuroglial cell that can phagocytize
mircoglia
what is the CNS neuroglial cell that helps control levels of K+ in the brain
astrocytes
what is the neuroglial CNS cell that only allows fat-soluble substances to leave the blood and enter the brain
astrocyte
what is the neuroglial CNS cell that can help metabolize certain neurotransmitters
astrocyte
what is the neuroglial cell in the CNS that makes myelin
oligodendrocyte
what is the neuroglial cell in the CNS that lines spaces within the brain
ependymal cells
neuroglial cell in PNS that makes myelin
Schwann cell
what is the nucleated, cytoplasmic layer of Schwann cell
neurilemma
what is another name for the cell body of neuron
soma
perikaryon
rough ER in the perikaryon (soma) of a neuron goes by this name
Nissl Bodies
a neuron with more than two extensions off of the soma
multipolar neuron
a neuron with 2 extensions off of the soma
bipolar neuron
a neuron with 1 extension off of the soma
unipolar neuron
what is the stage in a twitch called when there is a change in charge across the membrane of a neuron due to Na+ influx
depolarization
what is the name for the stage in a twitch when there is a reestablishment of membrane potential in a neuron due to K+ outflow
repolarization
what is the term used to describe the propagation of the action potential at nodes of Ranvier only
saltatory conduction
what are common neurotransmitters in the autonomic nervous system
noradrenaline, norepinephrine, acetylcholine
what is a type of neurotransmitter that blocks plain
endorphins
what is the most common excitatory neurotransmitter in the brain
glutamate
what is the most common inhibitory neurotransmitter in the brain
GABA
what is a neurotransmitter that plays an important role in sleep and mood
serotonin
what is a neurotransmitter that is a gas and relaxes smooth muscle
nitric oxide
what is the term used to describe the change in resting membrane potential when it becomes more negative
hyperpolarization
what is the term used to describe a partial hyperpolarization caused by a neurotransmitter at the post synaptic membrane
IPSP
inhibitory post synaptic potential
what is the word for combination of EPSPs (excitatory postsynaptic potentials) that makes it easier for the postsynaptic membrane to reach threshold
summation
what type of neuroglial cell in the PNS that maintains the environment around neurons
satellite cell
what is the threshold amount that will open the Na+ voltage-gated channel at the node of Ranvier
-55mV
where would be a place where a chemically-gated channel can be found on a neuron
the post synaptic neuron membrane