Action Potential
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
|
|
||||
|---|---|---|---|---|---|
| What are axons? | They are long, thin structures than conduct a signal called an action potential
🗑
|
||||
| What is a nerve? | A bundle of axons
🗑
|
||||
| What occurs at the trigger zone? | An action potential is usually initiated at the junction of the axon hillock at the initial segment
🗑
|
||||
| What is the initial segment? | A myelinated axon's first region
🗑
|
||||
| What happens once an action potential is generated? | It is regenerated down the membrane of the axon. In other words the action potential is propagated or conducted down the axon.
🗑
|
||||
| An action potential is usually initiated in an axon or near... (3) | axon hillock, initial segment and the trigger zone
🗑
|
||||
| The initiation of an action potential in a sensory neurone in the body normally... | follows a sufficiently large depolarising receptor potential
🗑
|
||||
| What is the threshold voltage? | The voltage at which you first observe action potential
🗑
|
||||
| What change in membrane potential triggers a change for action potential? (2) | A depolarization in the membrane potential results in an action potential. The membrane potential must become less negative in order to trigger an action potential.
🗑
|
||||
| How did the action potential at R1 (or at R2) change as you increased the stimulus voltage above the threshold voltage? | The action potential didn't change as the stimulus voltage increased. This is because once the threshold is met, the even is all or none, not graded.
🗑
|
||||
| An action potential is an "all-or-nothing" event. Explain what is meant by this phrase. | This means that once the threshold is met, an action potential occurs. If the stimulus is too small an action potential does not occur.
🗑
|
||||
| What is the approximate concentration of K+ inside a typical cell (intracellular concentration)? | 150 mM
🗑
|
||||
| What is the approximate concentration of K+ outside a cell (extracellular concentration)? | 5mM
🗑
|
||||
| What is the approximate concentration of Na+ inside a cell (intracellular concentration)? | 5 mM
🗑
|
||||
| What is the approximate concentration of Na+ outside a cell (extracellular concentration)? | 150 mM
🗑
|
||||
| What does it mean that the voltage just inside the membrane is negative? | There are more negative charges than positive charges just inside the membrane.
🗑
|
||||
| The membrane of most cells, including neurons, contains passive, open, K+ leak channels. Given the normal K+ concentrations and the resultant concentration gradient, which direction would K+ be expected to move (diffuse) through these leak channels? | Out of the cell
🗑
|
||||
| What effect does increasing extracellular K+ have on the net diffusion of K+ out of the cell? | It decreases the net diffusion of K+ .
🗑
|
||||
| Which way would Na+ move across the membrane if there were open Na+ channels? | Na+ would diffuse into the cell.
🗑
|
||||
| Changing the extracellular Na+ concentration does not significantly change the membrane potential. What do your results suggest about the number or state (open or closed) of Na+ channels in the resting membrane of a neuron? | Na+ channels are mostly closed.
🗑
|
||||
| Which of the following caused a change in membrane potential from -70 to -40 in the cell body? | an increase in extracellular K+
🗑
|
||||
| A negative membrane potential was recorded when the tip of the microelectrode was | both inside the cell body and inside the axon.
🗑
|
Review the information in the table. When you are ready to quiz yourself you can hide individual columns or the entire table. Then you can click on the empty cells to reveal the answer. Try to recall what will be displayed before clicking the empty cell.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Created by:
meunid