# ActionPotential

> ActionPotential traces the membrane potential of an action potential on axes of time (0 to 6 ms) against millivolts, drawing it in duration seconds from…

Page: https://fframes-kit.pages.dev/docs/biology/action-potential/
Cargo feature: `biology` (`fframes-kit = { version = "..", features = ["biology"] }`)

`ActionPotential` traces the membrane potential of an action potential on axes of time (0 to
6 ms) against millivolts, drawing it in `duration` seconds from `delay`, a dot at its head.
The dashed threshold (-55 mV) and resting (-70 mV) lines are there from the start, and each
phase is named as the trace reaches it: resting potential, stimulus, depolarization, the peak,
repolarization and hyperpolarization. `membrane_potential(ms)` gives the curve. Gallery
scene: `ActionPotential`.

Gallery clip of `ActionPotential`: https://fframes-kit.pages.dev/media/scenes/ActionPotential-a92f27f6.mp4

```rust
use fframes_kit::prelude::*;
use fframes_kit::kits::biology::membrane_potential;

assert_eq!(membrane_potential(0.0), -70.0);
assert!((membrane_potential(2.3) - 40.0).abs() < 1e-6); // the peak

fn spike<'a>(ui: &mut Ui<'a, '_, '_>) -> Svgr<'a> {
    ui.show(ActionPotential { duration: 3.0, ..ui.defaults() })
}
```

## API

Components are plain structs. Set the fields you need and fill the rest with `..ui.defaults()`: the defaults below come from the current theme (`theme.` values are fields of `Theme`).

### ActionPotential

| Field | Type | Default | Description |
| --- | --- | --- | --- |
| `delay` | `f32` | `0.0` | Seconds after the container's start before the trace begins to draw. |
| `duration` | `f32` | `5.0` | Seconds the trace takes to draw from 0 to 6 ms. |
| `center` | `(f64, f64)` | `(0.0, -0.3)` | The middle of the axes, in units of `ui.space`. |
| `x_length` | `f64` | `9.0` | Width of the axes, in units of `ui.space`. |
| `y_length` | `f64` | `5.2` | Height of the axes, in units of `ui.space`. |
| `trace_color` | `Color` | `Color::hex("#ffd43b")` | Colour of the trace and the dot at its head. |
| `threshold_color` | `Color` | `Color::hex("#ff8787")` | Colour of the dashed threshold line (-55 mV). |
| `axis_color` | `Color` | `theme.colors.muted` | Colour of the axes and the dashed resting line (-70 mV). |
| `label_style` | `TextStyle` | `label_style` | The font of the axis labels and numbers: family, size in pixels and weight. |
| `phase_style` | `TextStyle` | `theme.typography.caption` | The font of the phase names along the trace: family, size in pixels and weight. |
| `text_color` | `Color` | `theme.colors.text` | Colour of the phase names. |
| `enter` | `Option<FadeIn>` | `None` | Fade in at the start; `None` for none. |
| `exit` | `Option<FadeOut>` | `None` | Fade out before the end; `None` for none. |

Feature `biology` · [Source](https://github.com/khanhthanhdev/fframes-kit/blob/main/fframes-kit/src/kits/biology/neuron.rs#L439)