Stress Response and General Adaptation Syndrome

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Questions and Answers

What is the definition of allostasis?

A state where the body's systems are in balance.

A state where the body is in a state of alarm.

The sum of biological reactions caused by a stressor.

The overall process of adaptive change to maintain survival and well-being. (correct)

What is a stressor?

The feeling of being overwhelmed.

A physiological reaction to a challenging situation.

The overall response to stress.

An agent or condition that disrupts homeostasis. (correct)

According to Hans Selye, what are the three stages of the General Adaptation Syndrome (GAS)?

Threat, Response, and Resolution

Stress, Adaptation, and Recovery

Alarm, Resistance, and Exhaustion (correct)

Stimulus, Response, and Feedback.

Which of the following statements accurately describes the relationship between homeostasis and allostasis?

Homeostasis is a static state, while allostasis is a dynamic process of adaptation. (A) Signup and view all the answers

What is the primary function of the alarm stage in the General Adaptation Syndrome?

To initiate the stress response and mobilize resources. (D) Signup and view all the answers

Which of the following accurately describes the role of the hypothalamus in the Alarm stage?

It senses a stressor and activates the sympathetic nervous system. (D) Signup and view all the answers

What is the primary function of the catecholamines released during the Alarm stage?

To provide energy for fight or flight responses. (C) Signup and view all the answers

What is the primary effect of the hypothalamic-pituitary-adrenal (HPA) axis being activated during the Alarm stage?

Release of glucocorticoids, like cortisol. (D) Signup and view all the answers

What is the key difference between the Alarm stage and the Resistance stage?

The Resistance stage is characterized by a return to homeostasis, while the Alarm stage is the initial response to stress. (C) Signup and view all the answers

What happens when the body fails to recover from the Alarm stage and enters the Exhaustion stage?

The body's energy stores are depleted, and it can no longer adapt to stress. (A) Signup and view all the answers

Which of the following is NOT a characteristic of the Exhaustion stage?

Increased production of catecholamines. (C) Signup and view all the answers

What is the significance of the pathologic triad seen in the Exhaustion stage?

It represents the body's failure to return to homeostasis. (D) Signup and view all the answers

What is the key takeaway message about the Exhaustion stage in the context of stress response?

It highlights the importance of early and adequate stress management. (B) Signup and view all the answers

Which of the following is NOT a factor that can contribute to allostatic load?

Effective regulation of allostatic responses (B) Signup and view all the answers

Which statement accurately describes the difference between allostasis and allostatic load?

Allostasis refers to the process of maintaining stability, while allostatic load represents the wear and tear resulting from that process. (B) Signup and view all the answers

What is a key limitation of GAS theory in explaining stress?

It does not adequately account for the role of psychological factors in stress. (A) Signup and view all the answers

Which of the following is an example of a psychological stressor, as described in the content?

Feelings of sadness (C) Signup and view all the answers

Which of the following accurately describes the relationship between stressors and allostasis?

Stressors trigger allostatic responses, which are attempts to maintain stability. (B) Signup and view all the answers

What is the primary role of norepinephrine in the cardiovascular system?

To constrict smooth muscle in blood vessels (C) Signup and view all the answers

Which of the following hormones is secreted by the adrenal cortex and increases protein synthesis in the liver?

Cortisol (B) Signup and view all the answers

What effect does cortisol have on muscle and lymphoid tissues?

Has a catabolic effect (A) Signup and view all the answers

What is the function of aldosterone in the context of fluid volume?

Raises blood pressure by enhancing sodium reabsorption (C) Signup and view all the answers

Which neurohormones are primarily responsible for inhibiting pain during stress?

Endorphins and enkephalins (A) Signup and view all the answers

What role does epinephrine play in the body during stress response?

Increases heart rate and contractility (D) Signup and view all the answers

How does stress affect reproductive hormones in females?

Suppresses luteinizing hormone and estradiol (B) Signup and view all the answers

What is the primary effect of glucocorticoids compared to catecholamines?

Slow onset and longer duration (D) Signup and view all the answers

Which hormone is produced during childbirth and also acts to promote social bonding?

Oxytocin (D) Signup and view all the answers

In what way can allostatic overload occur?

When adaptive mechanisms are inadequate (B) Signup and view all the answers

Study Notes

Stress Response

Homeostasis is the state where all systems are balanced at a specific "set-point."
Allostasis is the process of adapting to maintain survival and well-being.
Stress is the sum of biological responses when homeostasis is disrupted.
Stressors are agents or conditions that cause stress and initiate allostasis.

General Adaptation Syndrome (GAS)

Hans Selye theorized GAS in the 1920s.
GAS has three stages: alarm, resistance, and exhaustion.

GAS: Alarm Stage

The "fight-or-flight" response.
A surge in energy and physical changes to either run or confront danger.
The hypothalamus senses a threat (internal or external, physical or emotional).
Hypothalamus activates the sympathetic nervous system (SNS).
Adrenal medulla releases catecholamines (epinephrine and norepinephrine), enabling the body to fight or flee.
Corticotropic-releasing hormone (CRH) from hypothalamus stimulates anterior pituitary gland to release adrenocorticotropic hormone (ACTH).
ACTH triggers adrenal cortex to release glucocorticoids, especially cortisol.
Hypothalamic-pituitary-adrenal (HPA) axis is activated.
Alarm stage happens in full force; cannot be deactivated once the pituitary gland is activated.
Prolonged activation leads to permanent body damage.
SNS, adrenal medulla, and cortex fully function during alarm stage.

GAS: Resistance Stage

Allostatic return to homeostasis.
SNS activity, catecholamine and glucocorticoid secretion get normalized.
Body returns to a steady state if stressors are adequately addressed and resolved.
Body has "adapted" or "increased resistance" to the stressor.

GAS: Exhaustion Stage

Body cannot return to homeostasis.
Adaptive energy stores are depleted.
Body cannot adapt further.
Pathological triad (hypertrophy of adrenal glands, atrophy of lymphoid tissues, and bleeding GI ulcers).
Death is possible if homeostasis is not restored.

Allostatic Overload

When adaptive mechanisms are inadequate, allostatic overload may occur.
Many physiological and psychological effects occur from excessive stress.

Neurohormones of Stress and Adaptation

Catecholamines: Norepinephrine (NE) and epinephrine (Epi).
- Released from the CNS in response to stressors.
- NE released by sympathetic neurons near organs/tissues.
- NE and Epi released from adrenal medulla into bloodstream to enhance the SNS.
Norepinephrine and epinephrine:
- Norepinephrine is a primary blood vessel constrictor, regulating blood flow and maintaining blood pressure.
- It reduces GI activity, dilates the iris, and relaxes ciliary muscles for better vision.
- Epinephrine increases heart rate, myocardial contractility, venous return, and raises cardiac output/blood pressure.
- Epinephrine also increases glycogenolysis and blood flow to the brain, enhancing mental attention and alertness.
Adrenocortical steroids (cortisol and aldosterone):
- Have regulatory roles in cardiovascular system, fluid volume, metabolism, immunity, inflammatory responses, brain function, and reproduction.
- Cortisol is a lipid-soluble hormone and its effects last longer than catecholamines.
- Cortisol supports catecholamines by promoting epinephrine synthesis and controlling blood pressure/cardiac output.
- Cortisol increases liver protein synthesis but has a catabolic effect on other tissues, stimulating gluconeogenesis (liver) for glucose availability (especially to nerve cells). It also promotes appetite and suppresses inflammation and acute-phase responses.
- Aldosterone is a primary mineralocorticoid that's released in response to stimulation of the SNS to enhance sodium reabsorption in kidneys, increasing ECF volume and blood pressure.
Other neurohormones (endorphins, enkephalins, and sex hormones):
- Endogenous opioids (endorphins, enkephalins) inhibit pain naturally by raising pain threshold, producing sedation, and euphoria. They are released in response to stressors, e.g., by laughter, massage, or acupuncture.
- Sex hormones (e.g., cortisol) affect stress, and vice versa. For instance, cortisol inhibits the female reproductive system (luteinizing hormone, estrogen, progesterone) but androgens(testosterone, DHEA) oppose the catabolic effects of cortisol and lower levels of stress related depression. Stress often lowers testosterone levels.
- Oxytocin, combined with estrogen, is calming during stress. Oxytocin is also produced during childbirth, lactation, and orgasm, promoting bonding and social attachment.
Growth hormone and Prolactin:
- Released during intensely stressful physical/psychological stimuli.
- Growth hormone enhances protein synthesis, fat mobilization, and decreases carbohydrate utilization, impacting immune function.
- Prolactin is also released during stress, sexual activity, and breast feeding with functions similar to growth hormone, including immune regulation.
Stressors:
- External (e.g., pollution, accidents).
- Internal (e.g., low blood sugar, feelings of threat).
- Physical/Chemical/Biological/Social (e.g., injury, exhaust fumes, viruses, bad relationships).
- Psychological (e.g., sadness).
- Emotional stressors can be present or anticipated.
- Can be low-intensity impacting over time.
Risk factors: increase the likelihood of experiencing a stressor.

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Description

Explore the mechanisms of stress response and the General Adaptation Syndrome (GAS). This quiz covers concepts like homeostasis, allostasis, and the three stages of GAS theorized by Hans Selye. Test your understanding of the physiological changes triggered during the alarm stage of stress.