All Nervous system Flashcards
Where is potassium concentration highest?
inside the cell (makes it more negative inside the cell)
where is sodium concentration highest?
outside the cell
has more positive charge
what does the Na/K atpase pump do?
Pumps 3 sodium ions out and brings 2 potassium ions in
What prevents equilibrium of Na and K in the cell??
Na+/K+ ATPase pumps so we
(refer to the resting membrane
potential to be in the steady-
state)
what is the equilibrium potential for sodium?
+65 mV
what is the equilibrium potential for potassium?
-85 mV
what is an EPSP?
EPSPs will change the resting membrane potential to become more positive
What is an IPSP?
IPSPs will change the
resting membrane potential
to become more negative
what is spatial summation?
multiple neurons fire at the same time, but from different locations
and the areas of depolarization overlap
what is temporal summation?
multiple stimuli from the same
neuron occurs in rapid succession
Summation occurs at the _______ and starts the process of ________
axon hillock
axon conduction
When there is significant depolarization of the cell membrane what happens to Na channels?
they open causing significant depolarization (look at image on slide 382)
what helps repolarize the membrane?
opening of voltage gated K channels (downstroke)
what is the overshoot or delayed rectifier phase?
too much K enters making the cell hyperpolarized for a bit
what is the difference between absolute and relative refractory periods?
- The absolute refractory
period is the time when a
second action potential
cannot be conducted no
matter how great the
stimulus. - The relative refractory period
is the time when voltage-
gated sodium channels are
resetting, and a second
action potential can be
conducted as long as the
second stimulus is greater
than the first.
What inactivation also
allows the axon
potential to be
conducted in one
direction
Na channel inactivation (as the impulse travels down axon the Na close to make sure the potential only goes down the axon and not back up)
the larger the diameter of the axon, what happens?
less internal resistance so higher conduction velocity
where might you find large axonal diameter nerons?
Type A-alpha nerve fibers.
* These are efferent skeletal
muscle motor neurons
Type A-beta are involved in:
pressure and touch sensations.
HIGHLY MYELINATED
- Type A-delta are involved in:
fast pain, such as extremes in
pressure and temperature.
highly mylinated
- Type C fibers are involved in
slow pain and are postganglionic
autonomic nerve fibers.
not myelinated
________ are responsible for the development of the resting membrane potential.
Leak channels
______ leak channels make up the majority of this channels and allow for the resting membrane potential to be negative.
Potassium
Once the membrane potential meets threshold at the axon hillock, then an action potential will occur. This will require the opening of _____________
voltage-gated
sodium channels
_____________ channels will be responsible for the upstroke of the action potential and will undergo rapid inactivation.
Voltage-gated sodium
This along with the opening of _________channels will cause the downstroke of the action potential.
voltage-gated potassium
Since voltage-gated potassium channels are slower in closing this will result in an after ________ phase
hyperpolarization (undershoot)
what is the difference between a electrical and chemical synapse
electrical: gap junctions that allow small molecules to pass
chemical: neurotransmitters
what is an ionotropic post synaptic receptor?
receptors allow for ions to enter into the postsynaptic cell (usually sodium or calcium)
In order for a neurotransmitter to be released, there must
be an _______________ within the terminal button
increase in intracellular calcium
what is an metabotropic post synaptic receptor?
receptors require cell metabolism, and this is typically through a G-protein coupled receptor (GPCR) pathway
is ionotropic or metabotropic receptors faster action?
ionotropic is faster
what are some ways signals are terminated at the chemical synapse?
diffusion, degradation, autoreceptors, reuptake, or endocytosis of postsynaptic
receptors
what is an example of an auto receptor?
Alpha-2 adrenergic receptor (auto receptors release the neurotransmitters to themselves)
what do neuromodulators do?
enhance or diminish the
pre-synaptic and postsynaptic membrane potential
The neurotransmitter must then bind to either an_____ or ______ receptor unless it is a gaseous neurotransmitter.
ionotropic or metabotropic
The action potential is conducted down the axon to open up:
voltage- gated calcium channels. Calcium is the GO signal!
Increase in intracellular calcium at the terminal button will cause:
exocytosis of neurotransmitter and release into the synaptic cleft.
What are peripheral receptors?
specialized cells in the peripheral nervous system that respond to stimuli and allow us to perceive and interpret the world
examples chemoreceptors, mechanoreceptors, baroreceptors, thermoreceptors
nociceptors
what is anesthesia?
The loss of sensation or conscious response to a stimulus
(this is a destructive lesion)
what is Paresthesia?
an abnormal feeling of touch, such as tingling, burning, prickling, numbness, or pins & needles
what is hypesthesia?
a reduced sensitivity to touch. It can be temporary or permanent (irrative lesion)