Neurophysiology: Electrical Signaling

Question 1

Neurophysiology

Answer 1

Study of specialized life processes that allow neurons to use chemical and electrical processes to sum up vast amounts of info and pass to other neurons

Question 2

Resting potential

Answer 2

Resting neuron is polarized (inside of cell more negative than outside)

Achieved by distribution of ions

Maintained by semipermeable membrane

Question 3

Anion

Cation

Answer 3

Anion- negatively charged ion

Cation- positively charged ion

(Both are dissolved in intracellular and extracellular fluid)

Question 4

Ionic forces

Answer 4

Diffusion (concentration gradient)

Electrostatic pressure

Question 5

Diffusion (concentration gradient)

Answer 5

Move from high concentration to low concentration

Like food coloring in water

Question 6

Electrostatic pressure

Answer 6

Move away from like charge toward opposite charge

Question 7

Equilibrium potential

Answer 7

Electrical charge that balances forces of diffusion and electrostatic pressure

Corresponds with resting potential (~-60mV)

Maintained by semipermeable membrane

Question 8

Leaky channels

Answer 8

K+

Always open

Question 9

Voltage gated Na+ ion channels

Answer 9

Open in response to change in membrane voltage

Depolarization threshold (-40mV)

Na+ enters the cell (moving down concentration gradient and electrostatic pressure)

Question 10

Voltage-gated K+ channels

Answer 10

Open in response to depolarization

K+ exits the cell (moving down concentration gradient, against positive inside electrostatic pressure)

Question 11

Na+K+ Pump

Answer 11

Maintains polarity by pumping out 3 Na+ for every 2 K+ in

Restores resting potential

Question 12

EPSP

Answer 12

Excitatory postsynaptic potential

Pushes postsynaptic cell closer to threshold for AP

depolarization (less negative inside, more similar to outside)

Cations (Na+) move in

Question 13

IPSP

Answer 13

Inhibitory postsynaptic potential

Pushes cell away from threshold for AP

hyperpolarization (more negative inside)

Anions (Cl-) move in

Question 14

Integration

Answer 14

Local potentials sun at axon hillock

Resting potential ~-60mV

Threshold ~-40mV

Question 15

Spatial summation

Answer 15

Multiple different EPSPs help meet the threshold

Question 16

Temporal summation

Answer 16

EPSPs in quick succession help to meet the threshold

Question 17

Absolute refractory phase

Answer 17

Inactivated voltage-gated Na+ channels

No APs are produced

Question 18

Relative refractory phase

Answer 18

Hyperpolarized due to K+ exiting the cell

Strong depolarization need in order to produce AP

Question 19

What impacts AP conduction velocity?

Answer 19

Myelination- (myelinated=faster) saltatory conduction

Diameter of Axon- (wider=faster)

Question 20

Chemical synapse

Answer 20

Large distance between pre/post synaptic cells

Chemical messengers span space between neurons

Slow

Question 21

Electrical synapse

Answer 21

Much less common than chemical

Gap junctions

Very small distance between pre/post synaptic cells

Ions can flow into the pre and postsynaptic cell directly

Very fast (and activates a lot of things at once)