什么是压力反应

Stress is a biological and psychological response experienced upon encountering a threat that we feel we do not have the resources to deal with.

A stressor is a stimulus (or threat) that causes stress, e.g., an exam, divorce, the death of a loved one, moving house, or loss of job.

Sudden and severe stress generally produces:

• Increase in heart rate
• Increase in breathing (lungs dilate)
• Decrease in digestive activity (don’t feel hungry)
• Liver releases glucose for energy

Firstly, our body judges a situation and decides whether or not it is stressful. This decision is made based on sensory input and processing (i.e., the things we see and hear in the situation) and also on stored memories (i.e., what happened the last time we were in a similar situation).

If the situation is judged as being stressful, the hypothalamus (at the base of the brain) is activated.

The hypothalamus in the brain is in charge of the stress response. When a stress response is triggered, it sends signals to two other structures: the pituitary gland and the adrenal medulla.

The fight or flight response produces these short-term responses via the Sympathomedullary Pathway (SAM). Long-term stress is regulated by the Hypothalamic-Pituitary-Adrenal (HPA) system.

The Hypothalamic-Pituitary-Adrenal (HPA) System

Chronic stress response: hypothalamic-pituitary-adrenal system (HPA) system.

1. The stressor activates the Hypothalamic Pituitary Axis
2. The hypothalamus stimulates the pituitary gland
3. The pituitary gland secretes adrenocorticotropic hormone (ACTH)
4. ACTH stimulates the adrenal glands and releases the stress hormone cortisol
5. Cortisol releases stored glucose from the liver (for energy), enabling the body to maintain steady supplies of blood sugar
6. Adequate and steady blood sugar levels help a person cope with a prolonged stressor and control swelling after an injury. The immune system is suppressed while this happens.

Sympathomedullary Pathway (SAM)

The hypothalamus also activates the adrenal medulla. The adrenal medulla is part of the autonomic nervous system (ANS).

The ANS is the part of the peripheral nervous system that acts as a control system, maintaining homeostasis in the body. These activities are generally performed without conscious control.

The adrenal medulla secretes the hormone adrenaline. This hormone gets the body ready for a fight-or-flight response. The physiological reaction includes an increased heart rate.

Adrenaline leads to the arousal of the sympathetic nervous system and reduced activity in the parasympathetic nervous system.

Adrenaline creates changes in the body, such as decreases (indigestion) and increased sweating, increased pulse, and blood pressure.

Once the ‘threat’ is over, the parasympathetic branch takes control and brings the body back into a balanced state.

No ill effects are experienced from the short-term response to stress, and it further has survival value in an evolutionary context.

Evaluation

Strengths

• Measuring stress hormones gives an objective measure of stress.
• Fight/flight response can be seen in all mammals in response to threats.

Weakness

• There is considerable variation in the level and type of hormones released by different people and in response to different stressors – not a simple physiological process.
• People without adrenal glands need hormonal supplements to survive stress.
• Symington (1955) found that conscious dying patients showed different stress reactions to unconscious ones. Suggests that psychological factors play a role.

References

Currie, A. R., & Symington, T. (1955). The pathology of the pituitary and adrenal glands in systemic disease in man. Proceedings of the Royal Society of Medicine, 48(11), 908.ReviewerAuthor

Olivia Guy-Evans, MSc

BSc (Hons) Psychology, MSc Psychology of Education

Associate Editor for Simply Psychology

Olivia Guy-Evans is a writer and associate editor for Simply Psychology, where she contributes accessible content on psychological topics. She is also an autistic PhD student at the University of Birmingham, researching autistic camouflaging in higher education.

什么是压力反应

压力是我们在遇到威胁时所经历的一种生物和心理反应，而我们认为我们没有资源来应对。

压力源是导致压力的刺激（或威胁），例如考试、离婚、亲人去世、搬家或失业。

突然而严重的压力通常会产生：

• 心率增加
• 呼吸增加（肺部扩张）
• 消化活动减少（不感到饥饿）
• 肝脏释放葡萄糖以获取能量

首先，我们的身体会判断情况并决定是否有压力。这个决定是根据感官输入和处理（即我们在该情况下看到和听到的东西）以及存储的记忆（即我们上次处于类似情况时发生的事情）做出的。

如果判断情况有压力，下丘脑（位于大脑底部）就会被激活。

大脑中的下丘脑负责应激反应。当应激反应被触发时，它会向另外两个结构发送信号：垂体和 肾上腺髓质。

战斗或逃跑反应通过交感髓质通路（SAM）产生这些短期反应。长期压力由下丘脑-垂体-肾上腺（HPA）系统调节。

下丘脑-垂体-肾上腺 (HPA) 系统

慢性应激反应：下丘脑-垂体-肾上腺系统（HPA）系统。

1. 压力源激活下丘脑垂体轴
2. 下丘脑刺激垂体
3. 垂体分泌促肾上腺皮质激素（ACTH）
4. ACTH 刺激肾上腺并 释放应激激素皮质醇
5. 皮质醇从肝脏释放储存的葡萄糖（作为能量），使身体能够维持稳定的血糖供应
6. 充足且稳定的血糖水平有助于人们应对长期的压力并控制受伤后的肿胀。当这种情况发生时，免疫系统会受到抑制。

交感髓质通路 (SAM)

下丘脑还激活肾上腺髓质。肾上腺髓质是自主神经系统（ANS）的一部分。

ANS 是周围神经系统的一部分，充当控制系统，维持体内的稳态。这些活动通常是在没有意识控制的情况下进行的。

肾上腺髓质分泌肾上腺素激素。这种激素让身体做好战斗或逃跑反应的准备。生理反应包括心率增加。

肾上腺素导致交感神经系统兴奋并减少副交感神经系统的活动。

肾上腺素会导致身体发生变化，例如减少（消化不良）和出汗增加、脉搏和血压增加。

一旦“威胁”结束，副交感神经分支就会开始控制并使身体恢复平衡状态。

对压力的短期反应不会产生不良影响，而且在进化背景下还具有生存价值。

评估

优势

• 测量压力荷尔蒙可以客观地衡量压力。
• 所有哺乳动物在应对威胁时都会出现战斗/逃跑反应。

弱点

• 不同的人在应对不同的压力源时释放的激素水平和类型存在很大差异，这不是一个简单的生理过程。
• 没有肾上腺的人需要补充荷尔蒙来应对压力。
• Symington（1955）发现，清醒的临终病人与无意识的病人表现出不同的应激反应。表明心理因素发挥了作用。

参考

AR 柯里和 T 赛明顿 (1955)。人类全身性疾病中垂体和肾上腺的病理学。英国皇家医学会会刊，48(11), 908。审稿人作者

奥利维亚·盖伊·埃文斯，理学硕士

心理学（荣誉）理学学士、教育心理学理学硕士

《简单心理学》副主编

奥利维亚·盖伊·埃文斯 (Olivia Guy-Evans) 是《Simply Psychology》的作家兼副编辑，她在其中提供有关心理学主题的易懂内容。她也是伯明翰大学的一名自闭症博士生，研究高等教育中的自闭症伪装。