Select your language

Suggested languages for you:
Log In Start studying!
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

All-in-one learning app

  • Flashcards
  • NotesNotes
  • ExplanationsExplanations
  • Study Planner
  • Textbook solutions
Start studying

Physiology of Stress

Save Save
Print Print
Edit Edit
Sign up to use all features for free. Sign up now
Physiology of Stress

Heart racing in your chest, and your breathing is getting quicker and quicker. Do these symptoms sound familiar? They are some physiological symptoms of stress; another example is altered PH levels in the body. The physiology of stress is when the homeostatic condition of the body changes as a result of encountering stressors. Researchers have identified several parts of the body that are activated when we are stressed, and these are responsible for the physiological causes of stress.

Homeostasis is the optimal condition that the body needs to be in, to work effectively.

Physiological impact of stress

What happens to our bodies when we are stressed?

The stress response is considered an innate response in animals (including humans). If the body is exposed to stress for too long, then the physiological effects of stress can damage the body. However, there are short-term evolutionary advantages to stressful encounters, such as helping us perceive and react to potentially harmful stimuli and situations. Therefore, it is essentially a survival mechanism.

When stressed, many changes occur in the body; the General Adaptation Syndrome describes the stages of stress that we experience and how these affect the physiology of our body.

The General Adaptation Syndrome (GAS)

The GAS model was proposed by Selye (1936) to describe what happens to the body when we experience stressors and how the body adapts to stressful situations.

Stressors are negative stimuli, events or threats that cause a physiological ‘stress’ response in the body. Some stressors are divorce, moving house, injury, losing a job, deadlines, work.

The model states that there are three stages that we experience when we encounter a stressor, these are:

  1. The alarm phase - the body kicks into “fight-or-flight mode” after encountering a stressor; this leads to a physiological response such as increased heart rate, quickened breathing.

  2. The phase of resistance - the parasympathetic branch is activated to try and calm the body and counteract the symptoms triggered by the alarm phase. The body does this by releasing the hormones adrenaline and cortisol. During this stage, a lot of the body’s energy is depleted.

  3. The phase of exhaustion - the body has used up all its energy resources, and it couldn’t counteract the stress symptoms. Continual exposure to this stage leads to cardiovascular and immunity problems.

Physiology of Stress Fight or flight StudySmarterImages to show the “fight or flight” response to stress (Image created in Canva using pictures from Pixabay)

What hormones are released when we are stressed?

The hormones that are released when we are stressed are adrenaline and cortisol. These hormones are released to stop the adverse effects of stress damaging our bodies.

Adrenaline and stress

Adrenaline is released when we are stressed. This hormone affects the sympathetic nervous system and triggers the fight-and-flight response. An increase in adrenaline leads to an increased heart rate. Adrenaline prepares the body by:

  • Fight - an increase in energy leads to heightened awareness of your senses so that you are best equipped to fight.
  • Flight - an increase in energy to provide you with energy so that you can run away.

Too much and too frequent exposure to high levels of adrenaline causes the heart to work harder, leading to cardiovascular problems.

Cortisol and stress

Cortisol is a hormone that helps regulate blood sugar levels, metabolism and reduces inflammation. Cortisol is also released when we encounter stressors. The hormone ‘turns off’ systems that are not needed in the body. The body is then better prepared to deal with stressors and can stop cells and hormones involved in inflammatory responses from being released. The body needs to have a balanced amount of cortisol to function correctly.

  • If we experience high cortisol levels too frequently, it can lead to health issues, such as immunosuppression. Chronic stress causes cells to become resistant to cortisol. Cortisol becomes less effective at stopping cells/hormones from causing inflammatory responses, compromising the functioning of the immune system.

  • Too little cortisol can cause tiredness, muscle weaknesses, weight loss and low blood pressure.

What causes the physiological symptoms of stress?

Two different pathways are activated when we experience stressful situations the Hypothalamic Pituitary Adrenal (HPA) system and the Sympathomedullary Pathway (SAM).

Physiology of Stress Physiological stress processes HPA & SAM StudySmarter

The HPA system and SAM pathway activation process, Sharon Thind - StudySmarter Originals

The Hypothalamic-Pituitary-Adrenal Axis (HPA) system

The purpose of the HPA system is to try and maintain homeostasis when we experience stress. The body needs to stay in optimal conditions, e.g., a specific temperature or pH to work properly; this is homeostasis. When we encounter stressful situations, the hypothalamus is activated, activating the pituitary gland. The pituitary gland releases a hormone, ACTH (adrenocorticotropic hormone), which is transported to the adrenal glands and responsible for the production of cortisol.

Corticosteroids are produced in the adrenal cortex, and are also a synthetic version of cortisol, mimicking the effects of cortisol in the body.

Cortisol turns off the systems, such as inflammatory reactions caused by the activation of the SAM pathway. People with high blood pressure are more likely to get inflammatory diseases.

Sympathomedullary (SAM) pathway

During stressful situations, the hypothalamus also activates the adrenal medulla, which works as a part of the Autonomic Nervous System. The adrenal medulla causes the release of adrenaline that is responsible for the “fight-or-flight” mode that we enter when we are stressed. The activation of this region leads to increased activity in the sympathetic nervous system and decreased activity in the parasympathetic nervous system; this is known as the SAM pathway.

Adrenaline (made in the adrenal medulla, and is a hormone) and noradrenaline (made in the sympathetic nervous system, and is a neurotransmitter) can act as hormones and neurotransmitters, but they favour one over the other respectively. Both help the body prepare for fight-or-flight.

Physiology of Stress - Key takeaways

  • The physiology of stress is when the homeostatic condition of the body changes as a result of encountering a stressor;
    • Homeostasis is the optimal condition that the body needs to be in, to work effectively.
  • The hormones that are released when we are stressed are adrenaline and cortisol. These hormones are released to stop the adverse effects of stress damaging our bodies.
  • The GAS model was proposed by Selye (1936) to describe what happens to the body when we experience stressors.
  • Two different pathways are activated when we experience stressful situations the Hypothalamic Pituitary Adrenal (HPA) system and the Sympathomedullary Pathway (SAM).

Frequently Asked Questions about Physiology of Stress

When you experience stressful situations you may have noticed an increase in your heart and breathing rate, this is the physiological symptoms of stress.

Increase in heart rate and breathing rate. The body's PH levels also change. 

When we are exposed to physiological symptoms of stress for too long then it can cause inflammation. Inflammation has been linked to many mental health illnesses. 

This is also known as the General Adaptation Syndrome (GAS) model which explains the three stages of stress (the alarm phase, the phase of adaptation and the phase of exhaustion) and the effects these have on the body. 

These have been linked to inflammation and cardiovascular problems. 

Final Physiology of Stress Quiz

Question

What type of stress does the sympathomedullary pathway respond to?

Show answer

Answer

Acute stress.

Show question

Question

What part of the brain is activated if a situation is judged to be stressful?

Show answer

Answer

Hypothalamus.

Show question

Question

What is the second stage of the sympathomedullary pathway?

Show answer

Answer

The autonomic nervous system (regulates physiological processes such as heart rate, blood pressure, respiration, and digestion), which includes the sympathetic nervous system, is aroused, and heart rate and blood pressure increase.

Show question

Question

What hormones do the adrenal glands release?

Show answer

Answer

Adrenaline and noradrenaline.

Show question

Question

What are the effects of adrenaline?

Show answer

Answer

Adrenaline boosts the supply of oxygen and sugar. It also stops non-emergency processes in the body, such as digestion.

Show question

Question

What are the effects of noradrenaline?

Show answer

Answer

Noradrenaline raises physiological arousal, prepares the body for ‘fight or flight’.

Show question

Question

After a threat disappears, what system brings the body back into a balanced state?

Show answer

Answer

Parasympathetic nervous system.

Show question

Question

What stress response do women tend to produce?

Show answer

Answer

Tend-to-befriend response.

Show question

Question

What did McCarty (1981) find about the responsiveness of the SAM as animals ages?

Show answer

Answer

Responsiveness of the SAM diminished, leading to reduced capacity to adjust to stressful situations.

Show question

Question

What did Horwatt et al. (1988) show acute stress responses? Pick one.


Show answer

Answer

Acute stress responses develop differently according to previous stress experiences.

Show question

Question

According to Lazarus (1999), what shaped a person’s response to a stressor apart from the physiological account?

Show answer

Answer

How we perceive the potential stressor (the demands of the stressor and our ability to cope with it) also determines our response.


Show question

Question

According to Speisman et al. (1964), what happened to the students’ heart rates when they positively interpreted the medical procedure?

Show answer

Answer

Heart rate decreased.

Show question

Question

The HPA axis consists of which three components?

Show answer

Answer

Hypothalamus, pituitary gland, and adrenal glands.

Show question

Question

What hormone does the pituitary gland produce? It is fine to use the shortened initials in answer.

Show answer

Answer

ACTH.

Show question

Question

What are the effects of cortisol? (5 effects)

Show answer

Answer

  • Releases a steady supply of blood sugar.
  • Lowered pain sensitivity.
  • Lowered immune response.
  • Diminished cognitive functions, such as concentration,
  • Slowing down of digestion.

Show question

Question

How long does the process of the HPA system take to complete?

Show answer

Answer

Around 20 minutes.

Show question

Question

The HPA system is self-regulating. What happens if high cortisol levels are detected?

Show answer

Answer

The levels of CRH and ACTH decrease, leading to a reduction of cortisol levels.  

Show question

Question

Which researchers demonstrated the effects of chronic stress on the immune system?

Show answer

Answer

Heim et al.

Show question

Question

What happens to the HPA system as a result of childhood trauma?

Show answer

Answer

Hypersecretion of CRH, leading to hyperactivity of the HPA system.

Show question

Question

Why is chronic stress not good for health?

Show answer

Answer

The body cannot relax, leading to excess cortisol in the body, leading to physical and mental health problems.

Show question

Question

What is the link between chronic stress and the immune system?

Show answer

Answer

Glucocorticoids, including cortisol, play a role in regulating the immune system and reducing inflammation. Chronic stress can impair communication between the immune system and the hypothalamic-pituitary-adrenal system.

Show question

Question

What is the link between the HPA system and depression?

Show answer

Answer

Due to an excess of cortisol, the cortisol receptors become desensitised, leading to noradrenaline and serotonin transmission disturbances.

Show question

Question

What do people who have had their adrenal glands removed need, showing the vital role of the HPA system in dealing with stress?

Show answer

Answer

Hormone supplements.

Show question

Question

Why is the HPA system not effective at dealing with long-term chronic stress?

Show answer

Answer

Our body system is old, still reacting the same way it would have done thousands of years ago when stress did not last as long. It was not equipped to deal with the modern stressors we face today for months or years.

Show question

Question

What does GAS stand for?

Show answer

Answer

General Adaptation Syndrome 

Show question

Question

What year did Seley propose the GAS model?

Show answer

Answer

1936

Show question

Question

What is the physiology of stress?

Show answer

Answer

When we experience stressful situations our body responds to this by increasing our heart rate, this is a physiological effect of stress. 

Show question

Question

How many stages are in the GAS model?

Show answer

Answer

2

Show question

Question

Which hormone is responsible for the "fight-and-flight" mode that is activated when stressed? 

Show answer

Answer

Cortisol

Show question

Question

Which hormone is responsible for reducing inflammation? 

Show answer

Answer

Cortisol

Show question

Question

Does cortisol affect the hypothalamic-pituitary-adrenal axis (HPA) system?

Show answer

Answer

Cortisol levels increase when we are stressed to try and prevent the activation of the HPA system from causing harmful effects. 

Show question

Question

What is the purpose of the HPA system? 

Show answer

Answer

To try and maintain homeostasis when stressed. 

Show question

Question

What are the pathways activated when we are stressed? 

Show answer

Answer

  • The hypothalamic-pituitary-adrenal axis (HPA) system
  • Sympathomedullary (SAM) Pathway

Show question

Question

Which are responsible for the production of cortisol?

Show answer

Answer

Adrenal medulla

Show question

Question

How does adrenaline help you "fight" a stressor? 

Show answer

Answer

Adrenaline gives a surge in energy that can heighten your senses so that you have a better chance of dealing with the stressor. 

Show question

Question

How does an increase in adrenaline help you 'run away' from a stressor?

Show answer

Answer

It gives you an increase in energy so that you can run away from the stressor. 

Show question

Question

Which stage of the GAS model can cause problems in the body? 

Show answer

Answer

The alarm phase

Show question

Question

What are the stages of the model proposed by Seley?

Show answer

Answer

  • The alarm phase 
  • The phase of adaptation 
  • The phase of exhaustion 

Show question

60%

of the users don't pass the Physiology of Stress quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Just Signed up?

Yes
No, I'll do it now

Sign up to highlight and take notes. It’s 100% free.