Discussion 11 Flashcards
What is the direction of electricity flow?
Electricity flows from the negative pole (source of electrons, higher charge) to the positive pole (lower charge).
What is electrical potential?
The ability to do work through the use of stored potential electrical energy.
Measured in volts.
What is electrical stimulation?
Passing an electrical current from the uninsulated tip of an electrode onto a nerve to produce behavior, such as a muscular contraction.
Who described the electrical activity of the neuron?
Alan Hodgkin and Andrew Huxley.
What is a nerve impulse?
A result of change in ion concentration across the axon membrane.
What did Hodgkin and Huxley win?
They won a Nobel Prize.
What is diffusion?
When molecules spread out from a point of high concentration to low concentration, requiring no additional energy.
What is a concentration gradient?
The difference in the relative abundance of a substance among regions that allows the substance to diffuse from an area of higher concentration to an area of lower concentration.
What is a voltage gradient?
The difference in electrical potential between two regions that allows a flow of current if the two regions are connected.Ions move down from an area of higher charge to an area of lower charge.
What happens when opposite charges interact?
Opposite charges attract.
What happens when similar charges interact?
Similar charges repel.
What is resting potential?
An electrical charge across the insulating cell membrane in the absence of stimulation.
What is the charge inside the cell compared to outside?
There is a store of negative energy on the intracellular side relative to the extracellular side.
What ions are more concentrated inside the cell?
Potassium (K+) and large proteins.
What ions are more concentrated outside the cell?
Sodium (Na+) and chloride (Cl-).
What maintains the resting potential?
The location of the ions, particularly the large A- molecules that cannot leave the cell.
What is the role of ungated potassium and chloride channels?
They allow K+ and Cl- to move in and out of the cell more freely.
What do gated sodium channels do?
They keep Na+ ions out of the cell.
What is the function of the Na-K pump?
It escorts leaking Na+ out of the cell and exchanges 3 Na+ for 2 K+.
What are graded potentials?
Small voltage fluctuations in the cell membrane restricted to the vicinity on the axon where ion concentrations change.
What is hyperpolarization?
An increase in electrical charge across a membrane, making the inside of the cell more negative.
What typically causes hyperpolarization?
The inward flow of chloride ions or the outward flow of potassium ions.
What is depolarization?
A decrease in electrical charge across a membrane, making the inside of the cell more positive.
What typically causes depolarization?
The inward flow of sodium ions.
What is the role of potassium channels in hyperpolarization?
They allow for the outward movement of potassium ions, reducing resistance.
What can cause hyperpolarization through chloride channels?
An influx of chloride ions can decrease resistance and result in a brief increase of Cl- inside the cell.
What happens when sodium channels open?
Depolarization can occur due to an influx of sodium ions.
What is Fugu?
Fugu (Japanese for pufferfish) contains Tetrodotoxin, a sodium channel blocker that impedes the electrical activity of neurons.
What is an inhibitory postsynaptic potential?
A brief hyperpolarization of a neuron membrane in response to stimulation, making the neuron less likely to produce an action potential.
What is an excitatory postsynaptic potential?
A brief depolarization of a neuron membrane in response to stimulation, making the neuron more likely to produce an action potential.
What is temporal summation?
Pulses that occur approximately at the same time on a membrane are summed.
What is spatial summation?
Pulses that occur at approximately the same location on a membrane are summed.
