Neural Conduction

Question 1

membrane potential

Answer 1

the difference of electrical charge between the inside and the outside of a cell.

Question 2

Resting membrane potential

Answer 2

• 70mV

* it’s 70mV less charged on the inside of the cell than the outside of the cell*

Question 3

random motion

Answer 3

ions move around randomly but are more likely to move down their concentration gradients (from high to low concentration)

Question 4

electrostatic pressure

Answer 4

opposites attract, like charges move away from each other

Question 5

sodium-potassium pumps

Answer 5

energy consuming mechanisms in the cell

-continually exchange 3 Na+ ions for 2 K+ ions

Question 6

depolarization

Answer 6

decreasing a resting membrane potential
(it becomes less negatively charged)
ex: -70mv => -55mv

Question 7

hyperpolarization

Answer 7

increasing a resting membrane potential
(it becomes more negatively charged)
ex: 30mv => -75mv
after an AP- the K+ channels let in too much

Question 8

excitatory postsynaptic potentials (EPSPs)

Answer 8

depolarizations of a neuron

increase the likely hood that a neuron will fire (closer to threshold)

Question 9

inhibitory postsynaptic potentials (IPSPs)

Answer 9

polarizations of a neuron

*decreases the likely hood that neuron will fire (further away from threshold)

Question 10

graded responses

Answer 10

amplitudes of EPSPs and IPSPs are proportional to stimulation
they can also combine to be bigger

Question 11

decremental

Answer 11

EPSPs and IPSPs decrease in amplitude as they travel through a neuron

Question 12

threshold of exitation

Answer 12

the level of polarization necessary to generate an Action Potential. *usually -60mV (10 less than the resting potential)

Question 13

action potential

Answer 13

a massive (1 millisecond) reversal of membrane potential (from -70mV to about +20mV)

Question 14

all-or-none response

Answer 14

APs occur to their full extent or not at all

they are not grade, they are all one amplitude and last for the same amount of time

Question 15

integration

Answer 15

combining a number of signals to create one overall signal

Question 16

spatial summation

Answer 16

when EPSPs and IPSPs occur at the same time, they combine to create one dip/rise/cancellation in the level of membrane potential

Question 17

temporal summation

Answer 17

when EPSPs and IPSPs occur in rapid succession, they can combine to create a greater signal

Question 18

voltage activated ion channels

Answer 18

located along the axons at the nodes of ranvier, these are protein channels that are activated to open at certain levels of membrane potential
usually during an AP

Question 19

absolute refractory period

Answer 19

a brief period (1-2 milliseconds after AP initiation) where another AP cannot occur

Question 20

relative refractory period

Answer 20

the period after an AP (2-4 milliseconds) when it is possible for the neuron to fire again, but only by applying higher than normal levels of stimulation

Question 21

orthodromic conduction

Answer 21

signals sent from the soma to the axon

Question 22

antidromic conduction

Answer 22

signals sent from the axon to the soma

• doesn’t happen naturally
• we can make it happen w/ drugs

Question 23

saltatory conduction

Answer 23

in myelinated axons, the signal can go faster bc the APs can jump farther distances
goes from node of ranvier to node of ranvier