Neural Communication & Drug Properties

Question 1

What does it mean to say that neuronal communication is an electrochemical process?

Answer 1

synapse- pre and post synaptic side

single neuron? membrane potential/voltage

a comparison between in and out

• inside vs + outside

two separate things

CHEMICAL because Na+ and K+ ions
moving around from in to our or vice versa, just somewhat controlled

ELECTRICAL because ions are +/- charged
as they move they change the potential/voltage of that area of the membrane

Question 2

Describe the chemical and electrical gradients for a neuron at rest.

Answer 2

chemical force pushing on Na and K

high concentration to low concentration

swimming pool - entry blocked- dye -

electrical force
wants to move where equal +/- of 0mV

they will be pushing on the same ions but in different directions

thus one is stronger and then they equal out=equilibrium

Question 3

What two proteins are responsible for the resting membrane potential? How so?

Answer 3

channels and pumps

channels

• a pore for specific passage
• ions move according to the gradients (high to low)
• ions against? yes. need ATP thus pumps

pump

• require ATP/ cellular energy
• push ions from low to high

Question 4

Describe how the resting membrane potential is established.

Answer 4

phospholipid layer doesnt have chemical or electrical gradient

NAK pump

• important because it takes up most of energy
• 3 na out for 2 k in for each action

chemical more sodium on outside, thus wants to move it in

K in and wants to go out

electrical- 3 + go out an 2+ in, leaves -1 inside. builds inside negative

Question 5

What two proteins are responsible for the action potential? How so?

Answer 5

NA+ channels - sitting closed at rest

• voltage activated ion channels
• when it reaches threshold, causes to change shape to open and NA flows in

K+ voltage gated channels

Question 6

Describe how an action potential occurs, including its threshold, stages, and refractory periods.

Answer 6

sum of esps and ipsp reaches the axon inital segment it reaches threshold of excitation, thus, passing that line = AP (-70 to +55
inside of membrane becomes + in respect to outside

if enough EPSP, then a Ap fires(all or none, not graded by percentage)

resting potential, depolorization/rising phase, repolorization, hyperpolarization

Question 7

Why does conduction only happen in one direction along the axon? Can you imagine a possibility in which conduction could travel in the opposite direction? (This likely happens in nature.)

Answer 7

Na+ gate is the culprit

inactivated. refractory - AP spreads in one direction

Question 8

Describe the differences between conduction in unmyelinated versus myelinated axons.

Answer 8

fewer channels to open

spent more time passively traveling

Question 9

Identify and define four key differences between postsynaptic potentials and action potentials. Additionally, describe where each occurs, and why.

Answer 9

PSPS
-receptors on dendrites
graded - different shapes
-Amplitude modulated; strength depending on size 
-RAPID
-Decremental -decay

AP

• channels on axons
• not graded, same shape
• Frequency modulated; stronger signal from frequency
• less fast; regeneration needed
• not decremental - do not decay, constantly regnerated