Physiological Responses to Stress

Kirsten Schuder
Stressed Woman

The body's response to stress is its natural, automatic response to a perceived danger or to an upsetting situation. It activates a chain reaction of events in the body known as the body's physiological responses to stress as it rises to the occasion to meet the stressful situation.

Fight or Flight Response

The fight or flight response refers to the physiological response to stress. It is the body's automatic response that occurs when we perceive a situation as dangerous or stressful. This sets off a chain of chemical and hormonal reactions so your body can be ready to fight or flee to keep you from harm.

Perceived Stress

Stress begins with our perception. The body's response to stress, whether it is a real, life-threatening situation or a perceived threat, produces physiological responses.

As Harvard Medical School explains, perceived stress starts in the senses and the brain.

  • When we see or hear a stressful event, the information is transferred to the brain.
  • There, the brain processes the information in the emotional processing center called the amygdala, and the information is transferred to the hypothalamus, the center that regulates the nervous system.
  • The hypothalamus then secretes ARH (adrenocorticotrophic releasing hormone).
  • The information is sent to the sympathetic nervous system which is the part of the nervous system that is in charge of sending out the alarm to the adrenal gland, the center in charge of the fight and flight response.
  • The adrenal gland sends out epinephrine, which is another name for adrenaline, to keep the body on high alert.

Secretion of Stress Hormones

The hypothalamus, which is also referred to as the master gland because it controls the endocrine system, secretes two stress hormones: CRH and vasopressin.

  • Vasopressin activates the ducts of the kidneys that are responsible for collecting water to take back some water from the kidneys and minimize the production of urine.
  • CRH induces the pituitary gland to make corticotrophin, which is brought to the adrenal cortex via the blood.

  • The adrenal cortex produces corticotrophin, which regulates the making of cortisol. The reason cortisol is produced is to help deliver the body from a state of stress back to a state of balance.

Increased Adrenaline Production

As the body readies itself for the emergency situation, it increases its output of adrenaline as a physiological response to stress. Adrenaline is responsible for sending out the emergency signal to various parts of the body to keep it in a state of alarm as long as the stressful event continues.

  • Adrenaline goes to the lungs, which causes the muscles in the lungs to loosen up so they can supply extra oxygen to the blood and you breathe in and out faster.
  • Adrenaline binds with the cells that regulate heart beat and causes the heart rate to rise, which also helps circulate the increased blood sugar.
  • Adrenaline also causes some muscles to tighten, which makes you sweat and the hairs on your body stand on end.

Increased Cortisol Production

Cortisol plays a role in both getting the body ready to deal with the emergency and for returning the body to a state of equilibrium once the stressful situation resolves itself. As Dartmouth University explains, cortisol produces a number of effects as it goes throughout the body to produce energy for handling the emergency, then return the body to a state of equilibrium.

  • Cortisol encourages the body to increase production of blood sugar so we can have the energy needed to react to the stressful situation. It also helps the blood sugar return to normal when the emergency is over.
  • In regulating potassium and sodium levels, cortisol returns the acidic/alkaline balance in the body to normal after a stressful situation.
  • With acute, short-term stress (like staring down a mountain lion), cortisol temporarily disables the immune system.
  • High levels of cortisol shut down the hippocampus, the area in the brain that is responsible for short-term memory.

Physical Signs of Stress

When the stress response initiates, you are probably not going to be aware that the hypothalamus is secreting stress hormones. However, you will probably know you are stressed because of the physical signs of stress upon your body. This is a result of your body shutting down all nonessential functions in order to meet the crisis, and supplying blood, oxygen, and glucose to the bodily functions that are needed to deal with the crisis.

  • Your thoughts are sharper.
  • Your blood pressure rises as your heart beats faster.
  • Your sight is sharper because the pupils open wider to allow more light.
  • You might feel like you need a shower because the apocrine glands increase their output and make your body smell.
  • You might not feel injuries as much because the pain receptors are shut down.
  • Your digestion and the elimination system temporarily shut down.
  • Your mouth gets dry, and your throat tightens.
  • You perspire and your skin might feel cool and moist.
  • Your hair stands on end.

Physiological Effects of Chronic Stress

The physiological stress response, the fight and flight response, is our way of surviving a crisis and is vital to keep us from harm. However, when stress becomes chronic, it can produce a host of health problems.

  • When the body is in a constant state of stress, cortisol and adrenaline upset the delicate hormonal balance in the body.
  • Continued immune system suppression leaves you open to more frequent colds and infections.
  • Stomach upset can lead to digestive disorders such as irritable bowel syndrome.
  • Excess cortisol upsets the balance of metabolism regulation resulting in weight gain.
  • Risk for diabetes increases because of cortisol's role in the regulation of blood sugar.
  • Susceptibility to physical aches and pain, such as muscle tension and headaches, increases.
  • Trouble either falling asleep or staying asleep may occur.
  • Sex life could suffer.
  • Women may experience negative impacts on their reproductive system and fertility.
  • Loss of focus and memory may occur due to shrinking in the hippocampus region of the brain due to excess cortisol.
  • Increased susceptibility to drug abuse and mental disorders, such as eating disorders, depression, and anxiety may occur.

Combat the Effects of Stress

Life events are first perceived as stressful before your body sounds the alarms. Therefore, while you can't control some of what occurs in your life, you can control your reaction to life events as well as change your current situation to help you alleviate your stress. Most importantly, just as stress has real physiological effects on the body, if you take measures to decrease your stress, the beneficial physiological effects you will produce on your body will be just as real.

Get Help

Most importantly, if you are feeling overwhelmed from stress, take the time to seek help for your symptoms. Seek help from a medical professional for any illnesses or disorders you are experiencing. Mental health professionals can be very useful to help you combat stress. They can help you to build your coping skills so you can handle life's daily stressors in a more productive way, or to help you with relationships that could be stressing you out, or even help you make a major life change. Reach out and don't feel like you have to do it alone.

Physiological Responses to Stress