Neural Conduction Flashcards
What ions are important in the action potential? When the cell is at rest, which ions are most highly concentrated inside of the cell, and which ones are most highly concentrated outside of the cell?
Sodium, Na+. Potassium, K+. Chloride Cl-. Calcium, Ca2+
K+ is greater inside. Na+, Cl- is greater outside.
Understand the forces working on the ions (electrical gradient and concentration gradient).
Electrical gradient- different charge inside vs outside. Ions flow to areas of opposite charge.
Concentration gradient- different levels of ions inside vs outside. Ions flow from areas of high to low concentration.
What is a voltage-gated channel? Where are they?
Opens when the cell reaches a certain voltage allows ions in or out. It is located on the axon, mostly the nodes
Understand the steps of the action potential, and how one leads to the next. How is an action potential started and propagated? What ion enters first? Thru what type of channel does it enter? What forces drive it inside? Why does that channel close? What channel opens next? What ion moves thru that? What forces drive that ion? Etc etc.
Sodium inside a cell diffuses to the next node of ranvier, causes the node to be -50mV then the sodium channel opens and sodium rushes in. Potassium channels open when sodium channels close. Potassium rushes out of cell. When it reaches -70, its resting and going to start over again.
Whats an action potential do?
sends signals across the synapse
When sodium rushes in……
it become depolarized
When potassium rushes out…….
it becomes hyper polarized
What voltage is resting potential?
-70 mV
Whats threshold?
depolarization that must be achieved to trigger action potential
Depolarized is…..
less negative than -70
Hyperpolarized is….
more negative than -70
Cell membrane is
always polarized
How could we depolarize the cell?
Add sodium
How could we hyperpolarize the cell?
Remove potassium.
What is the sodium/potassium pump? What does it do? What purpose does it serve?
For every 3 Sodium out, 2 potassium’s in.
Needed for maintaining rest potential and for recovery from an action potential
Removal of neurotransmitter?
Absorption by glia, enzymatic degradation, reuptake by presynaptic terminal
What is the purpose of myelin? What happens at the nodes of Ranvier? What is saltatory conduction?
What does it mean that an action potential is “all or none”?
Action potentials are generated in an “all-or-none” fashion. That is, in most (but not all) neurons, subthreshold depolarizations have no effect, but once the threshold is crossed, an action potential is generated
What is the difference between ionotropic and metabotropic receptors?
Ionotropic: Neurotransmitter binds to receptor and opens ion channel
Metabotropic: do not have channels. Neurotransmitter binds outside and that activates a G protein inside. The G protein can activate a second messenger which can find an ion channel and open it up. Takes longer than ionotropic, affects can be longer lasting
Know the common neurotransmitters.
Dopamine (Reward), Serotonin (Sleep), Norepinepherine (Adrenaline)
What is the most common excitatory neurotransmitter?
Most common excitatory NT: Glutamate
What is the most common inhibitory neurotransmitter?
Most common inhibitory NT: GABA
Where are neurotransmitters made?
Somas or teminals. The bigger ones are made in the somas.
What neurotransmitters share a pathway of synthesis?
Dopamine, Norephinephrine, epinephrine
What are the initial precursors for dopamine, norepinepherine, and epinepherine?
norephinpherine-epinepherine: Phenylalenine, tyrosine and dopa.
What are the initial precursors for serotonin ?
Tryptophan and 5-hydrozytryptophan
What are the initial precursors for acetylcholine?
Acetyl coenzyme A and Choline
What happens to neurotransmitters when they are released, and how are they cleared from a synapse?
Absorption by glia, enzymatic degration and reuptake by presynaptic terminal.
Can a neuron release more than 1 neurotransmitter? Can you think of an example of this?
Yes, the motorneurons in the spinal cord.
For dopamine and serotonin: what are they involved in?
Drugs
Whats a Agonist?
A drug that mimics or increases the effects of a neurotransmitter
Many antidepressants are serotonin agonists
Whats a Antagonist?
Drug that blocks the effects of a neurotransmitter
Many antipsychotics are dopamine antagonists
