Ronda Rousey lost in a spectacular way after only 48 seconds in the first round after getting in the ring with Amanda Nunes with a stunning knockout.

A professional fighter always runs the risk of being knocked out during a fight. What really happens during a knockout?

The skull is the bone encasing the brain. When a blow is placed to the head, this rocks the brain, pushing it against the wall of the skull.

When the force is strong enough to cause unconsciousness, cell death occurs. The more brain cells die the fewer brain tissues you have. In the recent match, Ronda Rousey was visibly stunned with the first few flurries of blows.

Nunes kept the pressure on and Rousey was unable to check the onslaught. The fight was stopped after 48 seconds as Ronda was visibly rocked by the powerful punches to her head and was unable to defend herself.

Ronda Rousey's lost to a powerful striker has been a shock as the former champion was not expected to be as easily defeated in such a fashion, but what really happens when you get hit in the head?

A professional fighter, take for example a boxer, can generate force of up to 400 kilograms. When hit with such force, the brain can shut down due to the trauma.

The impact of such force can and probably will probably leave a permanent effect on the recipient of such a blow. Brain volume is lost in the posterior and the frontal regions of the brain.

Mood changes, memory problems, confusion and slower information processing speed may be some of the lasting effects of suffering a massive blow to the head as reported in Medical Daily.

Amanda Nunes thinks that Ronda Rousey should hang up her gloves and retire. She went on to say that Rousey could not take her punches. And in an event of a rematch, Nunes said that she will do the same thing as reported in USA Today.