system
Given the following post, respond as if you're commenting on Reddit:
human
Why don't people bleed out during surgery?  When people get stabbed they bleed out.

The title is pretty self explanatory.  Surgeons cut pretty deeply.  It's my understanding that people feel pain when they get cut because it is the body signalling something is wrong.  So we give anesthesia to stop the patient feeling the pain.  But they are still bleeding!  For example, open heart surgery.  Do they just close the patient up before anything too bad can happen?  Or do they constantly recycle the lost blood through the patient's body artificially?

Thank you, knights of AskScience!
gpt
As you can see from the comments, there are lots of reasons that patients don't bleed out.  A non-comprehensive list:

* Surgeons avoid severing major veins/arteries whenever possible, and use hemostats to control bleeding.

* Minimally-invasive surgical techniques can reduce bleeding significantly.

* The patient's blood may be captured and recycled.

* Blood may be transfused.