Synapses Flashcards
How does the action potential travel?
from the dendrite to the axon
What is a pre synaptic cell?
cell that will be transmitting or sending something to other neuron
What is a post synaptic cell?
cell that receives something from another neuron
Where does synapse occur?
occurs between an axon of the pre-synaptic with the dendrites of the post-synaptic
What are the structures used to transmit the message from one neuron to the other?
axon terminals
an average neuron forms and receives how many synpatic connections?
1000 synaptic connections
What is synaptic transmission ?
is the way communication occurs between neurons in the brain
Where does neuron communication occur?
at special structures called synapses
If excitable cell membranes are in a resting state, the cells are ______?
polarized
What exactly is reffered to as membrane potential?
differences in charges across the membrane or difference in number of cations or anions
At a resting potential, neurons are at ?
-60 to -70mV
Depolarization
-Making cell more positve/less negative
-Na+ enters the cell
Hyperpolarization
Cell is more negative
How does the concentration gradient moves?
highly to low concentrated
Do to the concentration, how does K+,Na+,Cl- move?
K= is intracellular and moves toward the outside
Na= is extracellular and moves towards the inside
Cl= is extracellular and moves towards the inside
How does the ATPase work?
Against concentration gradient(uses energy)
K= travels towards inside of the cell
Na=travels towards the outside of the cell
Membrane permeability is the key to be able to create…..?
action potential
During resting state, how are the Na+ and K+ gated channels?
closed, they are deactivated
Voltage -gated channels only open when?
they are triggered by an action potential or there is a voltage difference across the cell membrane
What are the 2 types of Na+ gated channels ?
gate m= known as the ACTIVATION GATE. is normally CLOSED and opens when the cell starts to get more positive
gate n= known as the INACTIVATION GATE. normally OPEN, shuts down when the cell start to get TOO positive
What is the type of K+ gated channels?
gate n=is normally CLOSED, but slowly opens when the cell is depolarized (cell is very positive because Na+ enters the cell)
What is an action potential?
temporary shift of the membrane potential generated by excitable cells(neurons) due to the opening of the voltage gated ion channels
What is the function of the axon?
propagates the signal to the terminal and transmit to another neuron
What is the function of the soma?
encode information (head of the neuron)
What part of the neuron is the post-ganglionic neuron?
dendrites
Channels open when a _____________ binds to channel and opens it ?
neurotransmitter
What triggers an action potential?
binding of neurotransmitter(which causes the channel to open and thus depolorization occurs)
What are the steps of an action potential?
1 triggering event occurs= neurotransmitter binds to channel and causes it to open (causes positive ions to flow into inside of cell)
#2 Depolarization=makes the cell less polar(makes the cells more positive/less negative)
*Na+ voltage-gated channel used= m-gated channels
#3 Repolarization=brings cell back to resting potential
*gate h(inactivation gates) close
*gate n(K+ channels) open
#4 Hyperpolarization=makes cell more negative than its normal resting state
#5 Resting state
What is the type of Na+ channel present during the depolarization?
m-gated channel (located in the part of the axon closest to cell body) (channel activates due to the depolarization or Na+ ions entering the cell)
At what voltage is the membrane potential able to reach a threshold?
when it reaches -55mV (which is when an action potential is triggered to fire)
When is an action potential triggered to be fired?
when cell reaches threshold(-55mV)
When Na+ gated channels open during depolarization, Na+ ions enter the negatively charged _______ and depolorize the surrounding __________
Axon—–axon
What happens during the repolarization step?
-K+ channels open
-K+ ions flow more towards the outside of the cell, thus making cell less positive(returning cell into resting state)
What happens during the hyperpolarization step?
-cell becomes even more negative than the normal resting membrane potential
-K+ channels stay open, thus letting more postive ions leave cell(making cell more negative)
-when K+ channels close, sodium-potasium pump works to reestablish the resting state
Why are the refractory periods important?
-so brain doesn’t run out of action potentials
-so brain doesn’t get exhausted
stronger the stimulus , the __________ action potential
stronger the signal/ frecuency of the action potential
Stronger the action potential, _________ neuron fires up
faster the neuron fires up
Refractory periods help with replenishing ______________?
neutransmitter so that the message can keep passing along
When an action potential is triggered ,what happens?
eventually reaches axon terminal so that synapsis occurs
What can’t occur during the refractory period?
fire up another action potential
-h-gated Na+ channels = lock so no Na+ can enter the cell (no depolarization can occur)(no action potential can be produced)
What happens after refractory period?
-Na+ channels open causing depolarization and an action potential can be triggered
-cell are still hyperpolarized after sending action potential so it takes more postive ions to enter cell and cause depolarization
Refractory period can help determine the __________ of the stimulus
intensity of the stimulus
(ej: retina cells send a bigger/faster singal in a bright light than a dimmer light)
What are Saltatory conductions?
