neurotransmission I

Question 1

how do nerves make muscles move?

Answer 1

by transmitting electrical signals (action potentials) to muscles

Question 2

is nerve conduction the same in humans and animals like frogs?

Answer 2

Yes, though nerve conduction is much slower (~30–40 m/s) compared to electricity in wires.

Question 3

what is an electrical current?

Answer 3

flow of charged particles (electrons)

Question 4

what is voltage?

Answer 4

measure of stored electrical energy or potential for charge to move

Question 5

what is Ohm’s law?

Answer 5

V = IR (voltage = current x resistance)

Question 6

how is nerve conduction different from wire conduction?

Answer 6

nerves conduct via a slow wave of ion movement (action potentials), not rapid electron flow

Question 7

how do cells create electrical signals?

Answer 7

by moving ions like Na+, K+ and Cl- across membranes

Question 8

what is the resting membrane potential?

Answer 8

the voltage across the cell membrane when the neuron is at rest (~ -70mV)

Question 9

what ions are high outside the neuron?

Answer 9

Na+, Cl- and a bit of Ca2+

Question 10

what ions are high inside the neuron?

Answer 10

K+ and negatively charged proteins

Question 11

what are ion channels?

Answer 11

holes in the membrane allowing selective ion movement

Question 12

what is an electrochemical gradient?

Answer 12

the combination of an ions concentration gradient and electrical charge gradient

Question 13

what is an equilibrium potential?

Answer 13

the membrane voltage at which there is no net ion movement for a specific ion

Question 14

what is the nernst equation used for?

Answer 14

to calculate the equilibrium potential for an ion

Question 15

what maintains ion gradients?

Answer 15

the sodium-potassium pump (Na+/K+ pump)

Question 16

why is the resting membrane potential near -70mV?

Answer 16

the membrane is more permeable to K+ than to Na+

Question 17

what is an action potential?

Answer 17

brief wave of depolarisation that travels down an axon

Question 18

what triggers an action potential?

Answer 18

threshold voltage thar opens voltage-gated sodium channels

Question 19

how to ion channels affect membrane potential?

Answer 19

opening ion channels changes permeability and shifts membrane potential

Question 20

what are leak channels?

Answer 20

ion channels that are always open, especially for K+, helping set resting potential

Question 21

what happens first in an action potential?

Answer 21

threshold potential is reached, opening voltage-gated sodium channels

Question 22

what causes repolarisation?

Answer 22

sodium channels inactivate and voltage-gated potassium channels open

Question 23

what is hyperpolarisation?

Answer 23

Membrane potential becomes more negative than the resting level as K+ channels stay open briefly.

Question 24

What is the absolute refractory period?

Answer 24

When all sodium channels are inactivated; no new action potential can start.

Question 25

What is the relative refractory period?

Answer 25

Some sodium channels have recovered; a very strong stimulus can cause another action potential.

Question 26

Are action potentials graded?

Answer 26

No, they are all-or-nothing — they either happen fully or not at all.

Question 27

What sets the resting membrane potential?

Answer 27

Concentration gradients of ions and relative membrane permeability.

Question 28

Why is membrane potential closer to EK+?

Answer 28

The membrane is much more permeable to K+ than Na+ at rest.

Question 29

How does an action potential transmit signals?

Answer 29

By a brief, self-regenerating change in membrane potential that travels along the axon.