Problem, need urgent help...plz (communication) (1 Viewer)

[leeraff]

hello ppl, i need help with a dot point. Firstly im sorry if it has been answered somewhere else, but i couldnt find it.

Basically it is this.

define the term threshold and explain why not all stimuli generate an action potential

ive been told by my teach a bit of stuff.....but im not sure how deep we are meant to go into it. If somebody could provide some guidence i would be forever gratefull!!

THX!!

 

[swordfish]

The threshold is the amount of positive charge in membrane potential which is required before an action potential is produced. The depolarisation must reach a threshold which is at least 15mV more positive than resting potential of -70mV.
Also, each stimulus produces either a full action potential or none at all. Each action potential is a separate event. Therefore, a cell cannot produce another action potential until the previous one is complete.

well, that's straight from my notes, i dont think there's that much more to say....that's all i have anyway. I hope it helps a little!

 

[babydoll_]

Whoo! I was just about to type that! I got that pretty much exactly off a guy at the Helpline. Thanks swordfish!

BTW if you're worried about the graph (2nd column), think of the activation energy graph you use in chem. Looks like that

 

[Leap]

BTW if you're worried about the graph (2nd column), think of the activation energy graph you use in chem. Looks like that

i'm worried about the graph but i don't do Chem.
Could anyone explain, or maybe scan a copy of what this graph should look like for me? I'm so confused

 

[babydoll_]

Hmmm

well up to a point, there is no reaction to a stimulus

e.g if you walk into a dark room, you either see colour or you dont

once you reach the threshold, you can see colour

the graph looks like this:

 

[swordfish]

i think they would be more likely to give the data and ask us to plot it on a grid. It seems a bit cruel to ask us to remember all the numbers (even by board of studies standards!)

 

[babydoll_]

why? its just 70mV and -15mV.

 

[leeraff]

great thx for you help