Nerve Tissue Physiology Flashcards
what is considered the insulator of the nerve cell?
myelin
what is the conductor of the nerve cells?
water with dissolved ion
what kind of potentials happen at the dendrites and cell body?
graded
what kind of potentials happen at the axon?
action
movement of which ion is the key factor for cell membrane gradient?
Potassium
what does gaba stand for
gamma amino buteric acid
what kind of ion channels are at the end balls of the axon?
Ca++ voltage gated ions
why is it called a graded potential?
many stimulations are coming into the neuron and the graded potential allows the neuron to decide when to create an AP (does it reach the threshold or not?)
decremental
will travel in both directions down the plasma membrane
what is a seizure?
for some reason, an area of the brain misfires. all fire at once
- generalized tonic clonic
- absence
what are seizure meds?
gaba agonists (Cl hyperpolarizes neuron so it doesn’t misfire)
what is the big class of anti-anxiety?
benzos
xanax
valium
(hyperpolarize neuronal cell membrane)
glycine
inhibitory neurotransmitter
epsp
excitatory which depolarizes
ipsp
inhibitory which hyperpolarizes
gaba, glycine
where does summation occur?
only in graded potentials
AP is all or none
temporal summation
how frequently one neuron is releasing neurotransmitter onto our neuron
-close enough frequency that causes an AP
spatial summation
two simultaneous stimuli at different locations cause EPSP to add together
spatial summation of EPSP and IPSP
the two changes in membrane charges cancel each other out
how many moving parts does the sodium channel have?
2
which voltage gated ion channel is more complicated?
Na
absolute refractory period
time in which another AP cannot be fired no matter how much stimulus it has
(Na channel has to close inactivation gate and return to where activation gate is blocking)
relative refractory period
time frame in which you could fire another AP, but you have to have a stronger stimulus than usual (during hyperpolarization, you need a stronger stimulus)
hyperpolarization
end stage of the AP when K channels are slow to close
subthreshold potentials
graded potential didn’t get to firing first AP
membrane AP events are not dependent on…
stimulus strength
suprathreshold
graded potential gets an AP, but doesn’t make a greater AP…they all look the same (it will only change frequency)
large diameter axons conduct…
faster
1000 APs per second
larger diameter fibers offer less resistance to local current with more ions flowing per unit time
small diameter axons conduct…
slower
250 APs per second
how do APs move in axons?
in one direction
saltatory conduction
jumping from node of Ranvier to the next node
active zone
on neuron end ball where ligands are ready to go
snare and snap proteins
complex of cytoskeletal proteins that come together so that you pull it open to have a gap to release exocytosis
what is a neural modulator?
aid in effect of neurotransmitter or inhibit
autoreceptor
used in negative feedback system, decreases release of neurotransmitters
axon collateral
outcropping of the axon
-has a role in feedback on its own self
receptor desensitization
when a receptor responds once then fails to response despite neurotransmitters
what is the best example of always excitatory neurotransmitter
glutamate!
- can be neurotoxic, opens too many ion channels and kills neurons
- stroke patients
what does botox do?
prohibits release of acetylcholine
