nervous physiology Flashcards
what is the information pathway
sensory information is sent to the CNS, where it is integrated into motor information and sent away from the CNS
afferent pathway
sensory information sent TO the CNS
efferent pathway
motor information sent AWAY from the CNS
CNS
brain and spinal cord
PNS
nerves and ganglia
what part of the nervous system takes in and sends out information
PNS
autonomic nervous system
smooth muscle, cardiac muscle, and glands
is the autonomic nervous system voluntary or involuntary
involuntary
what are the two subdivisions of the autonomic nervous system
sympathetic and parasympathetic
sympathetic nervous system
fight or flight
parasympathetic nervous system
rest and digest
where are neurons found in the CNS
white matter
where are neurons found in the PNS
nerves
where are somas located in the PNS
ganglia
what do dendrites do
increase the surface area for receiving messages and catch graded potentials
what do axons do
carry out action potentials
what is myelin
a wrapping of cell membranes that are made of phospholipids
what does myelin do
increases the transmission rate of action potentials
neuroglia
supporting cells that outnumber neurons (about 10 to 1)
what neuroglia are found in the CNS
astrocyte, microglial, ependymal, and oligodendrocyte
what neuroglia are found in the PNS
schwaan, satellite
astrocyte
star cells that brace and support neurons and blood vessels, forms the blood-brain barrier
microglial
small, glue cells that defend the CNA and clean up damage, are motile
ependymal
cells that line the fluid-filled cavities in the CNS, lined with cilia
oligodendrocyte
branches of cells that myelinate
schwaan cells
multiple small single cells that wrap their membranes around an axon
satellite
cells that support/surround somas only in ganglia
what 2 things are neurons classified by
structure, function
multipolar neurons
most common, 99% of all neurons
bipolar neurons
rare, for sensory information in retina and nose
unipolar neurons
sensory neuron
sensory neuron function
bring information to the CNS, unipolar/bipolar
motor neuron function
bring information out of the CNS, multipolar
interneuron/association neuron function
within the CNS, multipolar
voltage (V)
the separation of charged particles (ions) the particles that are moving
resistance (R)
the hindering of charges particle flow from cell membranes
current (i)
the flow of charged particles (ions) across the membrane
ohm’s law equation
current = voltage/resistance
gated channels
channels that can be open or closed
ligand/chemical gated channels
a chemical binds to open or close a channel
voltage gated channels
if there is a charge change (v) across the membrane, the ion channel will open or close
mechanically gated channels
a pull on the membrane channel with open/close the ion channel
leakage channels
are always open, creates a constant slow current
resting membrane potential
the charge across the membrane (mV)
what ion is the membrane more permeable to at rest
potassium because of the leakage channels
graded potentials
a localized change to the membrane charge (V)
what does a big stimulus cause
more channels open –> bigger ion flow –> bigger voltage change
what does a small stimulus cause
less channels open –> less ion flow –> smaller voltage change
steps to a graded potential
1.) stimulus to cell
2.) induces ion channels to open up gated channels
3.) ions diffuse across the membrane at the current sink
4.) charge across the membrane
what does sodium diffusing into a cell cause
less negative charge, depolarization
what does potassium diffusing out of a cell cause
more negative charge, hyperpolarization
what does chlorine diffusing into a cell cause
more negative charge, hyperpolarization
what does calcium diffusing into a cell cause
less negative charge, depolarization
how many areas of a membrane do local potentials affect
1 area
decremental
potential voltage change decreases over a distance
how is the potential reversed
diffusion of ions away, ions pumping out of the cell
what do gated potentials add up to make
an action potential
non-decremental
recreated at the same voltage down the membrane
all or none rule (action potentials)
there is an action potential or there isn’t
what are refractory periods
when action potentials are unable to occur
absolute refractory period
the time frame when another action potential cannot occur
relative refractory period
the time after an action potential when the stimulus that is needed to get to threshold is increased
where is the action potential recreated on unmyelinated axons
along every part of the membrane
where is the action potential recreated on myelinated axons
the nodes (skip from node to node)
what does a bigger axon do for the action potential
bigger axon –> more ion flow –> increase in speed
electrical synapse
the gap junction, important in nerves system development
chemical synapse
predominated in the nervous system and uses neurotransmitters
axo-dendritic/somatic/axonic
all the places where an axon attaches to a post synaptic cell
where is ACh found
the neuromuscular junction, brain, and autonomic nervous system
amino acid neurotransmitters
GABA, glycine, aspartic acid, glutamate
GABA
the primary inhibitory neurotransmitter in the CNS, opens channels for chlorine to hyper-polarize
what do amines contain
nitrogen
amine neurotransmitters
catecholamines, serotonin, histamine
conversion of catecholamines
catecholamine –> dopamine –> norepinephrine –> epinephrine
serotonin
mood, sleep/wake, balance/coordination
histmine
function of hypothalamus
neuropeptides
chains of amino acids
neuropeptide neurotransmitters
substance p, enorphins, enkephalins
endorphins, enkephalins
inhibit pain
substance p
pain signals
how do gases work as neurotransmitters
as neuromodulators
neuromodulator
a chemical that can change/regulate neurons that are no released at the synapse (do not have a receptor, diffuse and excite/inhibit)
inotropic effect
the neurotransmitter opens an ion channel, allowing ions to diffuse across the post-synaptic membrane
metabotropic effect
uses 2 messengers, 1st messenger outside the ell –> stimulates G protein –> 2 messenger inside the cell
how does a signal stop
the neurotransmitter diffuses away, an enzyme breaks down the neurotransmitter, reuptake by the presynaptic neuron
synaptic delay
the more synapses that information has to pass through, the slower it happens
excitatory post-synaptic potential (epsp)
a depolarization occurs increasing the chance of an action potential
inhibitory post-synaptic potential (ipsp)
a hyperpolarization occurs decreasing the chance of an action potential
summation
adding up all epsp and ipsp
temporal summation
1 synapse firing repeatedly in a short time
spatial summation
more than 1 synapse firing at a similar time
when does an action potential occur
if the summation adds up to threshold (-55mV)
facilitation
generalized neuron excitement –> increase of action potentials
divergent pathway
few neurons –> many neurons
convergent pathway
many neurons –> few neurons
