do you burn calories when donating blood?

Not so's you'd notice unless you count the eyeblink crunches I did.

Your body burns calories every second that you're alive, in order to keep you alive. So, technically yes. Not from having blood taken from your body, but from the body having to reallocate resources towards fixing the broken skin from the puncture wound, having to get your marrow to create more blood and move it into your main blood vessels, having to pump your heart faster/ more powerfully until this happens because you've lowered your BP by removing liquid quantity from your blood vessels.

etc

in a word, no..........................

No, you do however decrease the impurities in your blood stream. For instance, cholesterol.

try this 101% sure try this extra smart - https://odysee.com/$/invite/HfdUhPSReidbDaznb8UQAK...

Yes.  Lots.   In fact,  homeostasis is the biggest user of energy. 

You burn calories sitting still.  It takes calories for you to breathe, and your heart to pump.  Your body is burning calories 24/7.

You burn calories by breathing

Significantly , no.  You make red cells all the time and loss of 1 unit of blood is really minor to the body red cell production is not sped up. The fluid is replaced from stores in hours. 

You burn calories just breathing but your body works to replace the blood cells donated so burns even more.