system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens in our brain when we "stand up to quick" causing our vision to go semi black and feel like were going to pass out?

This just happened to me, my vision went to the usual dotted blackness, just curious what is happening in my brain area during this.
gpt
Two words: Orthostatic Hypotension

OH happens when your blood pressure takes a dive. Usually, your body compensates when you go from sitting to standing by prompting your heart to beat a little faster (about an extra 10 beats per minute) and constricting your blood vessels, which force more blood back to your head and keep your brain on the up-and-up.

Many reasons, such as Dehydration, can cause OH and thus, Dizziness when you stand up too fast. 

I hope that was thorough enough, feel free to ask any more!