Concept Practice
The Stress Response System

Chapter 30. The Stress Response System

norepinephrine
one of the fast-acting stress hormones called catecholamines, released by the inner portion of the adrenal gland (the adrenal medulla); speeds heart rate, dilates blood vessels, boosts mood
pituitary gland
master gland of the endocrine system
stress
the body’s response to a threat or challenge
stressor
event or object that is the source of stress; any threat or challenge to a person
stress hormones
chemical messengers released into the bloodstream to arouse the body for action
sympathetic division
the part of the autonomic nervous system that arouses the body for action
adrenal gland
part of the endocrine system; located just above each kidney; releases stress hormones
autonomic nervous system
the part of the peripheral nervous system that regulates the internal organs
cortisol
one of the slow-acting stress hormones called glucocorticoids, released by the outer portion of the adrenal gland (the adrenal cortex)
epinephrine
one of the fast-acting stress hormones called catecholamines, released by the inner portion of the adrenal gland (the adrenal medulla); speeds heart rate, dilates pupils, and suppresses the immune system
glucose
type of sugar found in blood; main fuel burned by muscles and brain cells; low level of glucose triggers hunger
hypothalamus
limbic system structure that controls eating and other motivated behaviors, governs the body’s response to stress, and influences the endocrine system via the pituitary gland
The Stress Response System
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The image includes a figure of a woman sitting at a desk studying. Lines point to her brain and adrenal glands, which are visible. On the left side of the woman is a list of body parts that are part of the fast system. This list includes the following: hypothalamus, sympathetic ganglia, and inner part of the adrenal glands. On the right side of the woman is a list of body parts that are part of the slow system. This list includes the following: hypothalamus, pituitary gland, and outer part of the adrenal glands.
Learning Objectives:

Describe the body’s two stress response systems.

Understand the different roles that the body’s two stress systems play in our reactions to stressful events.

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The image includes a figure of a woman sitting at a desk studying. Lines point to her brain and adrenal glands, which are visible. On the left side of the woman is a list of body parts that are part of the fast system. This list includes the following: hypothalamus, sympathetic ganglia, and inner part of the adrenal glands. On the right side of the woman is a list of body parts that are part of the slow system. This list includes the following: hypothalamus, pituitary gland, and outer part of the adrenal glands.

1. Stress changes your body. When you are threatened or challenged—such as by a major writing assignment—your body's dual-track stress response system springs into action.

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A cross-section of a brain appears at the top of the image In the middle of the brain is the hypothalamus. An arrow leads away from the brain to the adrenal gland at the bottom of the image. This reprsents a fast channel where there is a short-term stress response through the spinal cord. The adrenal gland releases epinephrine and norepinephrine.

2. The faster track (called the fight-or-flight response) begins when the sympathetic division of the autonomic nervous system stimulates one part of the adrenal glands to release the fast-acting stress hormones epinephrine and norepinephrine (called catecholamines).

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The image includes a figure of a man. Lines point to various parts of his body with a description for each. At his head there is faster thinking. At his neck there is faster breathing. At his chest there is increased heart rate and output. At his arm there is increased blood pressure. At his stomach there is more glucose and fat for energy. At his leg there is increased blood flow to muscles.

3. Within seconds, heart rate and breathing rate increase, blood flows away from the digestive system and toward skeletal muscles, sensations of pain diminish, and the body releases small quantities of stored sugar and fat. This catecholamine system allows a rapid initial response to the stressor.

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A cross-section of a brain appears at the top of the image In the middle of the brain is the hypothalamus, with the pituitary gland right below it. An arrow leads away from the brain to the adrenal gland at the bottom of the image. In the middle of this arrow is the label for ACTH messenger. This reprsents a slow channel where there is a long-term stress response through the bloodstream. The adrenal gland releases cortisol.

4. In contrast, the slower track begins when the hypothalamus stimulates the pituitary gland. The pituitary releases a chemical messenger (called ACTH) into the bloodstream.

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The image includes a figure of a man. Lines point to his brain and adrenal glands. In his bain there is the hypothalamus, which leads to the pituitary gland. This leads to ACTH messenger being released through the bloodstream. This leads to the adrenal glands, which leads to the release of cortisol.

5. Within a minute or two, the message reaches the outer part of the adrenal glands, triggering the release of glucocorticoid stress hormones such as cortisol. Glucocorticoids help convert protein to glucose for use as energy. They also speed up the release of stored fat to be burned as fuel.

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A rescue team carries a girl away from a river.

6. This glucocorticoid system provides the energy for the body to maintain a sustained effort to battle against the stressor.

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Practice 1: The Fast Catecholamine System

Select the PLAY button to watch the fast stress response system in action.

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      Practice 2: The Slow Glucocorticoid System

      Select the PLAY button to watch the slow stress response system in action.

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          Quiz

          Drag each label to the gray area in front of an appropriate description. When all the labels have been placed, select the CHECK ANSWER button.

          Perhaps you should go back to review the role of stress hormones in the body’s response to system.
          Select the NEXT button and move to the Conclusion.
          Catecholamines (epinephrine and norepinephrine)
          Catecholamines (epinephrine and norepinephrine)
          Glucocorticoids (cortisol)
          Glucocorticoids (cortisol)

          Released from the outer part of the adrenal glands; part of the slow arousal system using messages passed through the hypothalamus and the pituitary gland.

          Released from the inner part of the adrenal glands; part of the fast arousal system initiated by the sympathetic division of the autonomic nervous system.

          Prepare the body for immediate "fight or flight" by speeding up heart rate and breathing, increasing blood flow to skeletal muscles, and slowing digestion.

          Prepare the body for sustained effort by speeding the release of stored fat to be burned for fuel, and converting protein to glucose as another source of energy.

          The Stress Response System
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          The image includes a figure of a woman sitting at a desk studying. Lines point to her brain and adrenal glands, which are visible. On the left side of the woman is a list of body parts that are part of the fast system. This list includes the following: hypothalamus, sympathetic ganglia, and inner part of the adrenal glands. On the left side of the woman is a list of body parts that are part of the slow system. This list includes the following: hypothalamus, pituitary gland, and outer part of the adrenal glands.
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          You have completed the activity The Stress Response System.