Listen to the AI-generated audio version of this article. (Beta)
The purpose of the stress response: preparing for fight or flight
Stress is a biological survival strategy that allows us to act with lightning speed in dangerous situations. In the early history of mankind – for example in the encounter with a predator – the stress response was crucial. It prepared the body for a quick decision: fight or flight. To this end, vital functions such as breathing, the cardiovascular system and energy supply were revved up. Unnecessary processes such as digestion or reproduction, on the other hand, were throttled back, in order to concentrate all resources on the immediate challenge.
This mechanism has proven itself over the course of evolution and has given living beings an enormous survival advantage. Unlike rigid instincts, the stress response enables flexible responses to new dangers. However, while this activation used to save lives, it often seems out of place in our modern world. Today, the same mechanism is triggered by stress at the office or in traffic – situations that can rarely be resolved with fight or flight. As a result, stress reactions can become counterproductive and even make it more difficult to cope with everyday challenges.
Stress arises in the brain
The starting point of every stress reaction lies in the brain, a highly complex information processor. The brain constantly receives signals from the environment via the senses, processes them and evaluates them in fractions of a second. When a danger is recognized, the brain activates a network of nerve cells and hormones, that puts the entire body on alert.
The three main players in the brain under stress:
- Brain stem: This developmentally oldest part of the brain is responsible for automated functions such as heartbeat and breathing. The”blue nucleus” (locus coeruleus) plays a key role as it produces the stress hormone noradrenaline.
- Limbic system: This includes the thalamus, which processes sensory signals, the amygdala, which triggers emotions such as fear , and the hypothalamus, which controls important hormones such as cortisol. The limbic system is often referred to as the”emotional brain” and is central to emotional reactions.
- Cerebral cortex: This”thinking apparatus” of the brain processes complex information, evaluates it and stores memories of previous situations. It helps us to anticipate potential dangers, However, it takes longer than the reflex reaction of the limbic system.
The course of a stress reaction
As soon as the brain recognizes a threat, the stress reaction runs through two”axes”:
- The fast axis (sympathetic-adrenal axis):
- Electrical impulses cause the release of adrenaline and noradrenaline.
- These hormones drive our heartbeat and breathing, supply the muscles with energy and make us ready for immediate action.
- The slow axis (hypothalamic-pituitary-adrenal axis):
- This is where the hormone cortisol is released, which prepares the body for prolonged stress.
- Cortisol mobilizes energy reserves, regulates the immune system and acts as a “supply organization” for the body.
While these mechanisms are helpful in the short term, they can overload and damage the body if stress persists.
How stress shapes the brain
Stress also has a direct impact on the structures in the brain. Two hormones play a key role here:
- Noradrenaline strengthens neuronal networks that are needed to cope with challenges. This leads to a learning effect during short-term stress: The brain memorizes successful strategies and reacts faster in similar situations.
- Cortisol, on the other hand, breaks down neuronal connections that have been shown to be ineffective during prolonged stress. In moderation, this is a sensible process that creates space for new solutions. In the case of chronic stress, however, cortisol leads to a breakdown of important structures, such as the hippocampus, which is responsible for memory and learning. The result: concentration problems and memory impairment.
Conclusion: stress as friend and foe
Stress is a natural mechanism that protects us in dangerous situations and promotes adaptation processes. However, in the modern world, the triggers are often different – and the stress response comes to nothing. In the long term , chronic stress can put considerable strain on the brain and body. A conscious approach to stress is therefore crucial, to take advantage of the positive effects – such as increased alertness and learning ability, without risking the negative effects.
