Nerve Impulses

Question 0

An electrical difference across the membrane of the cell called

Answer 0

Resting potential

Question 1

2 types electrical signal neurons

Answer 1

Graded potential - short distance communication

Action potential- long distance communication

Question 2

What in the cell membrane can open and close due to stimuli, changing the potential and creating an electrical current.

Answer 2

Specific ion channels

Question 3

What are ion channels

Answer 3

Transport channels for ions created by trans-membrane proteins within the neuronal membranes

Question 4

What happens when ion channels open

Answer 4

Allow specific ions to move through the membrane across an electrochemical concentration gradient.
Eg Na channels allow Na through

K channels allow k through

Question 5

4 categories of stimulus causing ion channels to open

Answer 5

Voltage
Chemicals
Mechanical pressure
Light

Question 6

What do neurons at rest possess across the cell membrane

Answer 6

Electrical difference/gradient

Question 7

How is neuron electrical difference across cell membrane created

Answer 7

Build up of intercellular negative ions and extra cellular positive ions

Separation of charges creates potential energy

Question 8

Voltage of resting potential

Answer 8

Approx -70mV

Question 9

Cells exhibiting membrane potential are said to be

Answer 9

Polarised

Meaning charged

Question 10

Na+ is

Answer 10

Sodium

Question 11

Cl- is

Answer 11

Chlorine

Question 12

K+ is

Answer 12

Potassium

Question 13

Describe extracellular fluid during resting potential

Answer 13

Rich in Na and Cl ions

Carries a POSITIVE charge

Question 14

Describe intracellular fluid in resting potential

Answer 14

Rich in K and large negative ions which cannot leave cell

Negative charge

Question 15

What do Na and Cl try to do during resting potential

Answer 15

Move back inside to equalise the charge

Question 16

How is resting potential polarity maintained by sodium potassium pump

Answer 16

Polarity maintained by

Pumping out 3 Na for every K it pumps back in

Question 17

What is an action potential

Answer 17

Formation of nerve impulse/signal/excitation

Series of events > decreases/reverses membrane potential then restores it to resting state

Question 18

2 phases action potential

Answer 18

Depolarisation

Repolarisation

Question 19

Define depolarisation

Answer 19

The negative membrane potential (-70mV) becomes less negative, reaches zero, then becomes positive.

Question 20

Describe depolarisation

Answer 20

After being positive the membrane is restored to its negative resting potential of -70mV

Question 21

Describe process of depolarisation

Answer 21

Triggered by stimulation of nerve ending
Na channels open allowing Na to flood into the cell
Positive charge builds up inside cell

Question 22

Describe process repolarisation

Answer 22

K channels open much more slowly than Na channels so just as Na channels are closing the K ones open.
Allows K to flood out of cell, restoring membrane potential to -70mV

Question 23

What is the refractory period

Answer 23

Period of time after repolarisation in which a nerve cannot generate another action potential because N and K are on wrong sides of the membrane

Question 24

What does Na-K pump do during refractory period

Answer 24

Pumps Na out and some K back into cell

Restores resting potential

Question 25

Difference absolute and relative refractory period

Answer 25

Absolute - even strong impulse can’t make action potential

Relative - larger than normal stimulus needed to generate action potential