nerve impulses action and resting potential

Question 1

when the nurone is at resting state -or resrting potential the outside of the neurone is…

Answer 1

positively harged and the inside negatively chrged

Question 2

describe how resting potential is maintained in an axon neurone

Answer 2

resting potential of the axon is -70 v
- maintained by sodium potassium pump and potassium channells
- sodium potassium pump , actively transports 3 Na+ ions out and 2K+ ions in.
- creates a sodium electrochemical gradient as axon membrane s not permiable to sodium ions so they cannot diffuse back in.
- axon membrane is permiable to K+ ions and diffuse out via potassium ion channels
- outside of the axon becomes positively charged and the inside negatively charged

Question 3

decribe the generation of action potential

Answer 3

• stimulus excites neurone causing sodium ion channels to open.
• as result of sodium ion channels opening rapid influx of soduim ions depolerising the axon.
• threshold value of +40 is reached
• sodium ions that have entered the neurone diffuse sideways causing a wave of depolerisation

Question 4

define refactory period

Answer 4

time delay between one action potential and anouther where ion channels cant be opened.

Question 5

define all or nothing principle

Answer 5

once threshold value is reached action potential will always fire with the same voltage no matter how big the stimulus