Beyond Fight or Flight 2: Run and Hide
Andy
Bodily responses to threat can be profound. That gut-wrenching, heartache, or ‘heart in the mouth’ moments are familiar to us all. Often we are unclear about the physiological causes of these experiences and therefore we find it difficult to understand them. Even when we seek this information, it is limited to the fight or flight response which only part-explains our experience and can lead us to have even more unanswered questions.
In this series of 'Beyond Fight or Flight' we explore three levels of autonomic nervous system response to safety and threat to develop a greater understanding of these responses.
When nobody is around to respond to our cries for help or notice our distressed facial expressions, and the threat continues to increase, our bodies move into a evolutionary older way of responding. The brakes (from new vagus nerve activity) are released and our bodies hit the accelerator pedal in the form of the fight or flight response.
This acceleration is signalled by the sympathetic nervous system. This increases blood flow to the muscles, heart rate and blood pressure. This is partly due to the release of adrenaline and cortisol (the longer-lasting stress hormone).
This is triggered to ensure our survival. As the sympathetic nervous system is a major branch of the autonomic nervous system, which regulates the organs that keep our body systems in balance, it is connected to several organs. Its activation therefore has a powerful effect on the body.
The fight or flight response mobilizes our muscles, the heart, lungs and sweat glands. The response also reduces salivation, activity in the stomach and intestines, and relaxes the bladder, as these functions aren't needed when we are fleeing or fighting. This whole-bodily response to immediate threat puts us in the best position to get out and hide or to fight the threat.
This response is evolutionarily older than the social engagement level 1 response and is responsible for our survival (and the survival or many other organisms) through millennia. During this time our lifestyle and environments have changed enormously, however the sympathetic nervous system has change very little. The sympathetic nervous system responds to any threats to us including physical threats, threats of rejection and abandonment (as we aren't good at surviving on our own), and unmet needs amongst others.
There are, however, situations when we are in inescapable danger. When we are trapped or held down, even the powerful response of the fight or flight cannot get us to safety. At this stage, the body's immobilization systems activate and we go into shutdown. See the 'Beyond Fight or Flight 3: Shutting Down' page for more details.
Summary of Levels:
3. Social communication or social engagement
• Facial expression, vocalization, listening.
• Dependent on the myelinated vagus, which originates in an area of the brainstem known as the nucleus ambiguus. The myelinated vagus fosters calm behavioral states by inhibiting the influence of the sympathetic nervous system on the heart.
2. Mobilization
• Fight-or-flight behaviors.
• Dependent on the functioning of the sympathetic nervous system, a system associated with increasing metabolic activity and increasing cardiac output (e.g., faster heart rate, greater ability of the heart to contract).
1. Immobilization
• Feigning death, behavioral shutdown.
• The most primitive component, shared with most vertebrates.
• Dependent on the oldest branch of the vagus nerve (an unmyelinated portion originating in an area of the brainstem known as the dorsal motor nucleus of the vagus).
