To have cold feet means to lose your nerve when facing a dangerous predicament. It’s meaning changed from nervous to coward centuries ago. This is a bit harsh because everyone’s body extremities become cold when nervous, not only of cowards. When the body knows you’re about to fight or run, it transfers all the blood into the vital organs instead of spreading it around like normally.
Did you know that there is no substance that can replace blood in your body and that 7% of your current body weight is blood, also an average adult has 14-18 pints of blood inside his body.