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Foundations of Neuroscience (Na+/K+ ion pumps (WHY: Contributes to…
Foundations of Neuroscience
Na+/K+ ion pumps
WHY:
Contributes to activating action potentials
Action potentials send electric impulses that send signals around the body for us to think & do
HOW
: Opening & closing of
sodium potassium pump
(a protein located around the axon) that changes the concentration of Na+ & K+ in a neuron
Resting potential
: More - ions inside the neuron compared to outside
Polar
-70 mV
Ion Channels
: Large proteins that open up K+ to go in the neuron
Voltage-gated channels
: Opens/closes up at certain membrane potentials
opens around -55 mV
Mechanically-gated channels
: Opens up when the membrane is physically stretched
Ligand-gated channels
: Opens up when a neurotransmitter latches into its receptor
Electrochemical gradient
: More + ions inside the neuron compared to outside
WHAT:
Transports 3 Na+ ions out of the cell & transports 2 K+ ions into the cell
Genes are NOT made out of protein
Action Potential
WHAT:
Stimulus that sends signals from one neuron to another
Action potential leads to a synaptic transmission
Presynaptic neuron: Neurotransmitters are pushed by action potential into a postsynaptic neuron (
travels a neuron's axon
)
Neurotransmitters can be in vesicles (
clumped up neurotransmitters
)
Ca+ enter presynaptic neuron
Postsynaptic neuron: Neuron receiving neurotransmitters from presynaptic neuron with its receptors (
received by the neuron's dendrite
)
Synaptic cleft: space between presynaptic neuron & postsynaptic neuron
Re-uptake: Process in which presynaptic neuron takes leftover neurotransmitters
Diffusion: Process in which leftover neurotransmitters in the synaptic cleft are flushed out
HOW:
All or None (
-55 mV
)
Polar
->
Depolarization
->
Repolarization
->
Hyper-polarization
of the membrane potential
Polar = More
- ions
inside the neuron (resting potential at -70 mV)
Depolarization = Na+ enter the neuron increasing
+ ions
at 40 mV
Repolarization = Membrane potential returns to resting potential
Hyper-polarization = More
- ions
inside the neuron (below resting potential; < -70 mV)
Same voltage for every signal, BUT different frequencies based on the stimuli
Occurs with sodium-potassium pumps when the stimulus is strong enough to cause the brain to send signals
Na+ outside the cell; K+ inside the cell that go in & out of ion channels