Instagram's favorite doctor is in the house. Board Certified Family Medicine Physician Dr. Mike Varshavski is explaining what to do in various emergency situations. Something has happened and someone is hurt — now what?

"There's a lot of crazy stuff happening in the news — major trauma scenarios — so people wonder, 'What's the first thing to do in case someone has a major cut, a gunshot wound? How can we prevent that person from bleeding out?'" Dr. Mike says. "As a doctor I think about what can we do to save the crisis in that moment."

If someone is bleeding out, the first thing you should do to help them is put as much pressure on the wound as you can, the doc explains. But oftentimes if they have a major gash or a gunshot wound, that's not enough. 

What you can do is make a makeshift tourniquet, he says — out of a belt or out of a dress shirt.

If you're wearing a shirt with sleeves, just rip the sleeve off of the shirt and tie it as tightly as you can, as close to the heart as possible. This will cut off the circulation and help the person lose less blood.

If the wound is at the bottom of the person's arm, for example, you should tie the tourniquet at the top of their arm because it's closer to the heart. 

You want to cut off the blood flow. When knotting the shirt, make it as tight as you possibly can. 

"You want to make the person scream, because by causing them pain you're also saving their life," Dr. Mike says. "You have to stop the blood flow. And this is going to give that person time in order to get the emergency responders to come and save their life."