“Neurotransmitters called Substance P* that alert the brain that it’s feeling pain are then released from within the testicles,” Dr. Mizra continues. “Substance P travels from the testicles up through the spinal column into the brain and is then processed by the part of the brain called the somatosensory cortex, which is responsible for processing physical sensations.”
*Would make a killer band name
The brain releases endorphins, which decrease the perception of pain. Dr. Mizra clarifies. “The production of these endorphins leads to decreased oxygen levels within the brain,” he explains. “Typically, in this type of situation, it can cause a throbbing headache and sometimes nausea. Because signals are also sent to the abdominal area, as this area shares the same set of pain receptors with the groin, the physical response would likely be holding onto the stomach and bending over and/or falling to the ground and going into the fetal position.” See? So, the girly reaction is biological, not wuss-related.