Question

action potentials

1. what are two other terms for an action potential?

1. true or false: all cells naturally have an equal charge on the inside versus the outside.
2. what do we call the difference in charge on the inside of a cell versus the outside?

1. what causes the difference in charge on the inside versus the outside of a cell?

1. which two ions are involved in membrane potential?

6 what is the charge inside of a cell naturally (positive or negative)? why is it this way?

1. what is a concentration gradient?

1. what does a concentration gradient cause?

1. if there are 6 k+ ions on the outside of a cell and 2 k+ ions on the inside of a cell, is there a concentration gradient?

Explanation:

Question 1:

Action potential is also called a "nerve impulse" as it's the electrical signal that travels along a neuron, and "spike potential" due to its rapid, spiking change in membrane potential.

Question 2:

Cells have a resting membrane potential, meaning there's a charge difference (inside is more negative relative to outside in neurons, for example). So the statement is False.

Question 3:

The difference in charge between the inside and outside of a cell is called the "membrane potential" (or resting membrane potential when at rest).

Question 4:

The charge difference is caused by the unequal distribution of ions (like $\text{Na}^+$, $\text{K}^+$) across the cell membrane, along with the selective permeability of the membrane to these ions. Ion pumps (e.g., sodium - potassium pump) also contribute by actively transporting ions against their concentration gradients.

Question 5:

The two main ions involved in membrane potential are potassium ($\text{K}^+$) and sodium ($\text{Na}^+$). Chloride ($\text{Cl}^-$) and calcium ($\text{Ca}^{2 + }$) can also play roles in some cells, but $\text{K}^+$ and $\text{Na}^+$ are the primary ones for the basic resting and action potential mechanisms.

Question 6:

The inside of a cell is naturally negative. This is because there is a higher concentration of negatively charged proteins and anions (like $\text{Cl}^-$) inside the cell, and also due to the distribution of cations: more $\text{K}^+$ inside but the overall balance of charges (with more negative - charged molecules and the effect of ion permeability) leads to a net negative charge inside.

Question 7:

A concentration gradient is the difference in the concentration of a substance (usually a solute like an ion) between two regions (e.g., inside and outside a cell). For example, there's a higher concentration of $\text{Na}^+$ outside a neuron and a higher concentration of $\text{K}^+$ inside, creating concentration gradients for these ions.

Question 8:

A concentration gradient causes the movement of a substance (ion or molecule) from an area of higher concentration to an area of lower concentration (this is called diffusion). In the context of cells, this can drive the passive movement of ions across the membrane (if the membrane is permeable to them), which is a key factor in generating membrane potential and in processes like the depolarization phase of an action potential.

Question 9:

To determine if there's a concentration gradient, we compare the concentrations. Here, there are 6 $\text{K}^+$ ions outside and 2 $\text{K}^+$ ions inside. So the concentration of $\text{K}^+$ is higher outside the cell than inside. Since there is a difference in concentration, there is a concentration gradient for $\text{K}^+$ (from outside to inside, down the concentration gradient).

Answer:

1. Nerve impulse, Spike potential
2. False
3. Membrane potential (or Resting membrane potential)
4. Unequal ion distribution (e.g., $\text{Na}^+$, $\text{K}^+$) across cell membrane, selective permeability, and ion pumps.
5. Potassium ($\text{K}^+$) and Sodium ($\text{Na}^+$)
6. Negative; Due to negative - charged molecules and ion distribution.
7. Difference in solute (ion) concentration between two regions.
8. Diffusion (movement of substance down its gradient).
9. Yes, because $[\text{K}^+]_{\text{outside}} > [\text{K}^+]_{\text{inside}}$.