An aggressive appearance is achieved by the erection of body hair and tensing of the facial muscles to expose the teeth. This, together with a general tensing of the body and the adoption of an aggressive posture, can give the impression of increased and imposing size aimed at frightening the opponent into retreat. Noradrenaline is involved in these responses.
Reducing activity of non-vital functions
Whilst fighting and fleeing, non-vital functions such as digestion and urine formation slow down or stop.
Tensing the muscles
The catecholamines increase the tenseness of the body muscles, keeping them partially contracted ready to spring into action. Muscle contraction strength is increased, particularly by noradrenaline.
Minimizing blood loss due to injury
Another set of alarm responses is aimed at reducing loss of blood in case of injury during the attack or escape. Noradrenaline increases the speed at which the blood clots. This, together with the constriction of the blood vessels in the blood redistribution process, means that there is less chance of serious blood loss if wounded.
Cortisol is released during and after the alarm reaction to reduce inflammation and assist wound healing so that injured tissues can be mended as soon as possible (see Figure 10, page 54).