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A polarized neuron has fewer positive ions inside in comparison to the outside of the neuron?
True
What is the chief positive intracellular ion in a resting neuron?
The chief positive intracellular ion in a resting neuron is a potassium ion. Just inside the cell of a resting neuron, the membrane is negative.
The chief positive intracellular ion in a resting neuron?
Potassium Ions (K+)
When cholinergic receptors are stimulated they?
sodium ions enter the postsynaptic neuron.
What condition is neuron in when the outside of the neuron has a net positive charge and the inside has net negative charge?
This is called the resting potential (inactive state) of the neuron. However, when a neurotransmitter binds to receptors, electrical stimulus is applied, etc. to induce an opening of ion channels in the membrane of the neuron, positive ions rush into the neuron from the outside to the inside, and result in a sharp increase of the positive charge density (due to more positive ions) inside the neuron. Beyond a certain threshold, this can induce the creation of an action potential, causing the neuron to fire. After the action potential is created, and the neuron fires, there is a short refractory period where the neuron cannot be fired again due to stimuli, when positive ions are pumped back out of the neuron, negative ions are brought into the neuron, and then the ion channels close, leaving the neuron in a polarized state, and returning it to a resting potential.
What is the first response a neuron makes to a stimulus?
Sodium ions enter the cell
What causes the inside of neuron becomes positive?
Outside a neuron, there are mostly sodium ions but some potassium ions. Inside the neuron, there are only potassium ions. Since both sodium and potassium are positive ions, and they are in a higher concentration outside the cell, that makes the outside have a more positive charge than the inside. But for all intents and purposes, the outside is positive, and the inside is negative. When the sodium ions (Na+) rush into the cell during depolarization, it causes the concentration of positive ions inside the cell to go WAY up, making the inside more positive than the outside. This means that the outside is now negative and the inside now positive.
Do sodium ions move to inside of neuron in a nerve impulse?
No. Three sodium ions are pumped out of the neuron by the sodium-potassium pump and two potassium ions enter the cell. This way you maintain a slightly negative charge just inside the cell membrane.
What is the resting potential and how is it created and maintained?
The resting potential is the voltage inside the neuron cell membrane of about -70 mV (negative 70 millivolts). This electrical potential (separation of charges) is made possible by an imbalance in sodium (positive), potassium (positive), and chloride (negative) ions on each side of the neural membrane. In the case of the resting potential, the surplus of chloride ions and relative deficiency of sodium/potassium ions within the neuron, relative to the outside of the neuron, give a charge difference of 70 millivolts, making the inside of the neuron more negative than the outside.There are ion channels that open and close based on voltages and other factors that are embedded in the neuron's cell membrane. When triggered by a nerve impulse, they open to allow for positive ions to stream into the nerve, which depolarizes it to generate the "signal".After the signal passes, the neuron resets itself by opening ion channels that pump positive ions back out of the neuron, and pump negative ions back in, in order to readjust to the resting potential again.
Circle the letter of the choice that describes an action potential?
a. Reversal of charges due to the flow of positive ions into a neuron
When calcium ions enter the synaptic terminal?
they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.
What initiates the depolarization of the neuron?
Most neurons are at a negative membrane potential so when a ligand operated channel opens there is an inflow of positively charged ions, mostly but not exclusively sodium. If the neuron cell membrane has voltage-operated channels (the textbook example) then the inflow of positive ions can open the voltage-operated channels causing an even greater flow of positive ions into the neuron. This positive feed arrangement can lead to the neuron transitioning from negative to respect to outside of the cell to positive (overshoot). Since the voltage-operated channels inactive and also due to the potassium specific channels the cell is returned it's pre-action potential negative level (close to potassium's equilibrium potential).
