COM- motor and sensory nerves Flashcards
What is faster a myelinated axon or unmyelinated
myelinated due to the jump in flow
what is velocity is desire - low or high
high
what is space constant
how far it goes before it decays
what is time constant
how fast the voltage travels before it decays
what determines a velocity of nueron
space and time constant
equation for conduction veloicty
space constant over time constant
time constant needs to be low - what determins this
capacitance and resistance
what is capacitance
the tendency of membranes to store electric charge
what is more important time or space c.
space
space constant is equal to what
medial resistance over the longitudinal resistance
big space constant is desired - by having what
a high medial resistance and longitudinal resistance
the voltage over time will
decay
Velocity is proportional to the number of what
space constant over time constant
anything that increases space or reduces time velocity will what
increase conduction velocity
what is the fastest a neuronal conduction is
120m
Resting membrane potential is what
the difference in electrical charge between inside and outside of the cell
The what allows pottasium and sodium to flow through
ion channel
what 2 ions flow in resting membrane potential
sodium and potassium
what effect takes place for pottasium
osmosis- highly concentrated to lowly concentrated
osmosis causes what to potassium
potassium to flow to the outside of the cell
potassium are high in intercellular - what kind of permeable and for what
permeable only for potassium
when the potassium leaves through the channels - what is caused
a build-up of positive eletrical charge outside the cell
the force of the charge build up is osmotic - and ends up being …
in equilibrium
positive charge coats the inside and negative coats
the outside in resting state of neuron
tendency of neurons firing using AP depends on what
the difference of voltage between inside and outside
the neuron using hyperpolarization and polarization will depend on what
weather the neuron will fire or not
depolarsation will result in
more likely to fire
hyperpolarization will result in
less likely to fire
the brain will decide what when firing neurons
what to fire or not
what amount of K and NA is needed for a molecule of ATP
2k+ and 3 NA+
What is the sodium potassium pump
energy dependent process of a neuron which results in K on the inside - setting a baseline for future firing
why does the brain use glucose
making atp for the sodium and potassium pump for neurons
how does action potential work
The voltage-gated ion channel embedded on the neuron - the channel opens or closes gate - depending on electrical charge ac ross the channel for sodium and potassium gates
What are the 3 states for sodium gates
resting channel which is closed , depolarized cell to threshold which can open and an inactive state / unresponsive
what are 2 states for sodium channels
resting / closed and depolarized
what are the 7 steps in AP positive feedback cycle
cell membrane depolarized,/ depolarization + NA channels open/ Na influx for more depolarization/ adjacent NA channels open / meanwhile k channels open slower causing K to flow out/ repolarizing the membrane and closing the sodium channels and becoming inactive
what is the difference in speed for k and na
sodium is quicker
differences between NA and K
permeability differs, sodium is quicker and is more permeable, pottasium is slower and effect is delayed -
what is the resting potential
-60/70 millivolts
AP is unidirectional - true or false
true
why is AP unidirectional / orthodromic
to stop channels reopening
temperature increases AP and
conduction veloicty
bigger diameter in neurons positively effects
Capacitance and decrease the medial resistance which affects conduction velocity
bigger diameter of neurons will increase the ..
speed of neurons
what does myelin do
insulate the axon
what is myelin made of
swan cells
what does myelin do
stops leaking, increases medial resistance
in myelinated axons, the AP is only occurs at the nodes - what kind of flow under their own voltage
passive ionic flow
what do the nodes do in myelinated axons
amplify the voltage to speed up conduction
passive flow is …. than amplified voltage in nodes of myelinated axons
slower
artificial stimulation is used by using a cathode to depolarize a muscle in the peripheral neurons
black cathode to stimulate nerve and muscle
anodal block is when
a neuron is deactivated after stimulation or too much stimulation
what is EMG
electromyogram / electromyography
what is EMG
Electromyography is a technique for evaluating and recording the electrical activity in muscles.
what is the 4 basic events in muscle contraction
AP stimulates the release of the Neurotransmitter across the NM junction/ AP spreads across sarcolemma/ muscle membrane and into fiber along T tubules ( this is the EMG signal) / causes calcium released from sarcoplasmic reticulum, calcium binds to muscle and causes cross-bridge cycling.
what is in the ventral horn of the spinal cord
the motor unit and it is innervated part of the muscle
what is one action potential in a muscle
one twitch
what happens when there is more than 1 action potential to a muscle
more twitches until it is too many and they all merge
higher frequency in twitches means what
how many the motor unit is firing
Twitch fusion is the concept of what
A high frequency of twitches which transitions into one big smooth contraction - this can and will result in more force from recruiting more fibres and a higher frequency
