Brain and Behavior Exam 2

action potential

brief and dramatic depolarization of the membrane of an axon; message sent down axons

cation

positively charged ion

anion

negatively charged ion

ion channel

pore through which ionsmay pass into or out of the cell; embedded in the membrane of the cell

sodium (Na+)

When no signl is traveling down an axon, ______ ions have a higher concentration outside the cell than inside the cell

Potassium (K+)

When no signal is traveling down an axon, _____ ions have a higher concentration inside the cell than outside the cell

diffusion

tendency for molelcules to distribute themselves evenly

electrostatic pressure

opposite charges attract; like charges repel; thus, ions tend to move to an area with its opposite charge

1. Na+ ion channels open

2. Na+ ions move inside the axon

3. K+ ion channels open

4. K+ ions move outside the axon

four steps of action potential

voltmeter

registers the difference in electrical charge between the inside and outside of the cell (membrane potential)

oscilloscope

records the changes in membrane potential over time

membrane potential

difference in electrical charge (in millivolts) between the inside and outside of a cell; in reference to axon potential it is the difference in electrical charge between the inside and outside of an axon

resting potential

membrane potential in the absence of stimulation or an action potential; it is a condition of polarization

negatively; -70mV

At resting potential the inside of the axon is ______ charged with respect to the outside. About how many millivolts?

graded potential

small voltage fluctuations across the membrane (between the inside and outside) of an axon

depolarization

when the inside of an axon is less negative than it was at resting potential

hyperpolarization

when the inside of an axon is more negative than it was at resting potential

threshold of excitation

minimum amount of depolarization needed in order for an action potential to occur

reversed polarization

a condition where the membrane potential has a positive value; occurs at the peak of an action potential “spike: when the membrane potential is a positive value

repolarization

when the membrane potential is retruning back to the resting potential after the peak of the action potential “spike”; occurs due to potassium (K+) ions axiting the ion

slatatory conduction

refers to the fast movement of a signal in a mylinated axon; action potentials only occur in the nodes of ranvier

decreases signaling (action potentials) in sensory neurons; decreases signaling by blocking sodium (Na+) ion channels in the senory neuron axons

How does lidocane work?

synapse

spatial junction between one neuron and another; forms the information transfer site between two neurons

anatomy of a synapse:

long structures containing muscle