The HPA Axis and Intrinsic Nature of The Stress Response
You are walking through the forest when all of the sudden you hear a twig snap behind you. You quickly spin around to discover a wolf stalking you. What do you do? How you respond in the next several seconds could be a matter of life or death. In moments like these, the most paramount of moments, there is no time to draw a venn diagram in your head and meticulously weigh out your options. Instead, an innate and instinctive reaction occurs which most people term “fight or flight”. Internally, your body has a trick up its sleeve that is essential for self preservation. This tool is called the HPA axis or Hypothamus-Pituitary-Adrenal axis.
In the context of a stressful event, like a bloodthirsty wolf following you, the HPA axis goes through the following pathway, “a hormonal cascade is initiated in response to the stressor with the release of corticotropin releasing hormone (CRH) from the hypothalamus, which stimulates the release of adrenocorticotropin releasing hormone (ACTH) from the pituitary gland. ACTH then triggers the breakdown of pregnenolone within the adrenal cortex into the glucocorticoid, cortisol, which is subsequently secreted into the blood circulation (Shea et al., 2005).” My project illustrates this pathway from Hypothalamus to Pituitary to Adrenal Cortex while highlighting the key hormones involved in the fight or flight response. Portraying the HPA axis during stress was my way of demonstrating the relationship between the endocrine and nervous system– a key objective from this semester. Additionally, to go beyond the material covered in the unit, I added in an image of a cat which symbolizes the “animal brain” and touches on unconscious thinking. This is an important component to understand when grasping human behavior and especially trauma. Dunlop and Wong (2019) are a pair of researchers who looked at the relationship between the HPA axis and PTSD. They admit in their account on the topic that there is much more to PTSD than the HPA axis and many factors including childhood stressors and sex will affect how the HPA axis responds in a PTSD scenario. However, some PTSD cases have been strongly linked to a dysfunctional HPA axis and above normal cortisol levels. The idea behind the linkage is that the hypothalamus, the unconscious, primal part of the brain, becomes overactive to stimulus causing increased reactivity to otherwise benign triggers. In the book, The Body Keeps Score by Bessel van der Kolk, which spent almost 150 weeks on the New York Times Bestseller list he outlines the hypothalamus’ importance in relation to trauma. He refers to the limbic system, which includes the hypothalamus, as the old or animal brain. The limbic system gets these names because it produces our primal instincts and was developed before the rational, thinking parts of the brain–evolutionarily speaking (p. 35). He specifies that the unconscious limbic system processes incoming information before other parts of the brain get the chance. This can lead to reactions that an individual has little say in. In PTSD the hypothalamus begins secreting stress hormones from otherwise normal stimuli because of a disturbance that has occurred in this quick defense mechanisms (p. 55). For instance, a hormonal reaction may occur from someone dropping something in the supermarket because it resembled the noise an individual heard before experiencing a bombing. The hypothalamus may then, without executive say, trigger a fight or flight response in the attempt to keep the individual safe.
It can be uncomfortable to think a vital piece of our machinery tasked to keep us alive can also be the root of our misery. I think it is natural to see ourselves as the captains of our emotions, but there is a bigger story. On deeper inspection, many parts of the brain that control our mood and hormones are unconscious, survivalistic areas.
Works Cited
Shea, A., Walsh, C., MacMillan, H., & Steiner, M. (2005). Child maltreatment and Hpa Axis
dysregulation: Relationship to major depressive disorder and post traumatic stress
disorder in females. International Society of Psychoneuroendocrinology, 30(2),
162–178. https://doi.org/10.1016/j.psyneuen.2004.07.001
Dunlop, B. W., & Wong, A. (2019). The hypothalamic-pituitary-adrenal axis in PTSD:
Pathophysiology and treatment interventions. Progress in
Neuro-Psychopharmacology and Biological Psychiatry, 89, 361–379. https://doi.org/10.1016/j.pnpbp.2018.10.010
Van der Kolk, B. A. (2015). The body keeps the score: brain, mind, and body in the healing
of trauma. New York, New York, Penguin Books.
Samantha Nixon
The HPA Axis, Hypothalamus-Pituitary-Adrenal axis, is the innate instinctive reaction we all love to call the “flight or fight response”. It is what controls our emotions and actions when faced with an emotional stressful event in our path, such as encountering a wolf out in the woods suddenly. The HPA axis goes through a hormonal cascade initiated by the response of the stressor, with the release of hormones eventually circulating through the blood stream. The project illustrates the pathway from the hypothalamus to pituitary and the adrenal cortex, all while highlighting key important hormones involved in the HPA axis or flight or fight response. The image of the cat represents the “animal brain” which symbolizes the unconscious mind or way of thinking. Two researchers who worked on the relationship between the HPA axis and PTSD, found that many cases of PTSD have been strongly linked to a dysfunctional HPA axis. Granted there are numerous variables that go into PTSD, the link to the HPA axis connects to the unconscious, primal part of the brain causing an overstimulation and increased reactivity in the brain. The book, The Body Keeps Secrets, outlines the connection between the limbic system and these primal instincts that take over as our “animal brain” when it comes to trauma. It can definitely become uncomfortable to think that something from our primal instincts that is supposed to keep us alive, can be turned against us and cause us so much misery. Showing that many parts of our brain controlling, hormones and our moods, derive from our unconscious survivalist instincts.
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The HPA Axis and Intrinsic Nature of The Stress Response
You are walking through the forest when all of the sudden you hear a twig snap behind you. You quickly spin around to discover a wolf stalking you. What do you do? How you respond in the next several seconds could be a matter of life or death. In moments like these, the most paramount of moments, there is no time to draw a venn diagram in your head and meticulously weigh out your options. Instead, an innate and instinctive reaction occurs which most people term “fight or flight”. Internally, your body has a trick up its sleeve that is essential for self preservation. This tool is called the HPA axis or Hypothamus-Pituitary-Adrenal axis.
In the context of a stressful event, like a bloodthirsty wolf following you, the HPA axis goes through the following pathway, “a hormonal cascade is initiated in response to the stressor with the release of corticotropin releasing hormone (CRH) from the hypothalamus, which stimulates the release of adrenocorticotropin releasing hormone (ACTH) from the pituitary gland. ACTH then triggers the breakdown of pregnenolone within the adrenal cortex into the glucocorticoid, cortisol, which is subsequently secreted into the blood circulation (Shea et al., 2005).” My project illustrates this pathway from Hypothalamus to Pituitary to Adrenal Cortex while highlighting the key hormones involved in the fight or flight response. Portraying the HPA axis during stress was my way of demonstrating the relationship between the endocrine and nervous system– a key objective from this semester. Additionally, to go beyond the material covered in the unit, I added in an image of a cat which symbolizes the “animal brain” and touches on unconscious thinking. This is an important component to understand when grasping human behavior and especially trauma. Dunlop and Wong (2019) are a pair of researchers who looked at the relationship between the HPA axis and PTSD. They admit in their account on the topic that there is much more to PTSD than the HPA axis and many factors including childhood stressors and sex will affect how the HPA axis responds in a PTSD scenario. However, some PTSD cases have been strongly linked to a dysfunctional HPA axis and above normal cortisol levels. The idea behind the linkage is that the hypothalamus, the unconscious, primal part of the brain, becomes overactive to stimulus causing increased reactivity to otherwise benign triggers. In the book, The Body Keeps Score by Bessel van der Kolk, which spent almost 150 weeks on the New York Times Bestseller list he outlines the hypothalamus’ importance in relation to trauma. He refers to the limbic system, which includes the hypothalamus, as the old or animal brain. The limbic system gets these names because it produces our primal instincts and was developed before the rational, thinking parts of the brain–evolutionarily speaking (p. 35). He specifies that the unconscious limbic system processes incoming information before other parts of the brain get the chance. This can lead to reactions that an individual has little say in. In PTSD the hypothalamus begins secreting stress hormones from otherwise normal stimuli because of a disturbance that has occurred in this quick defense mechanisms (p. 55). For instance, a hormonal reaction may occur from someone dropping something in the supermarket because it resembled the noise an individual heard before experiencing a bombing. The hypothalamus may then, without executive say, trigger a fight or flight response in the attempt to keep the individual safe.
It can be uncomfortable to think a vital piece of our machinery tasked to keep us alive can also be the root of our misery. I think it is natural to see ourselves as the captains of our emotions, but there is a bigger story. On deeper inspection, many parts of the brain that control our mood and hormones are unconscious, survivalistic areas.
Works Cited
Shea, A., Walsh, C., MacMillan, H., & Steiner, M. (2005). Child maltreatment and Hpa Axis
dysregulation: Relationship to major depressive disorder and post traumatic stress
disorder in females. International Society of Psychoneuroendocrinology, 30(2),
162–178. https://doi.org/10.1016/j.psyneuen.2004.07.001
Dunlop, B. W., & Wong, A. (2019). The hypothalamic-pituitary-adrenal axis in PTSD:
Pathophysiology and treatment interventions. Progress in
Neuro-Psychopharmacology and Biological Psychiatry, 89, 361–379.
https://doi.org/10.1016/j.pnpbp.2018.10.010
Van der Kolk, B. A. (2015). The body keeps the score: brain, mind, and body in the healing
of trauma. New York, New York, Penguin Books.
The HPA Axis, Hypothalamus-Pituitary-Adrenal axis, is the innate instinctive reaction we all love to call the “flight or fight response”. It is what controls our emotions and actions when faced with an emotional stressful event in our path, such as encountering a wolf out in the woods suddenly. The HPA axis goes through a hormonal cascade initiated by the response of the stressor, with the release of hormones eventually circulating through the blood stream. The project illustrates the pathway from the hypothalamus to pituitary and the adrenal cortex, all while highlighting key important hormones involved in the HPA axis or flight or fight response. The image of the cat represents the “animal brain” which symbolizes the unconscious mind or way of thinking. Two researchers who worked on the relationship between the HPA axis and PTSD, found that many cases of PTSD have been strongly linked to a dysfunctional HPA axis. Granted there are numerous variables that go into PTSD, the link to the HPA axis connects to the unconscious, primal part of the brain causing an overstimulation and increased reactivity in the brain. The book, The Body Keeps Secrets, outlines the connection between the limbic system and these primal instincts that take over as our “animal brain” when it comes to trauma. It can definitely become uncomfortable to think that something from our primal instincts that is supposed to keep us alive, can be turned against us and cause us so much misery. Showing that many parts of our brain controlling, hormones and our moods, derive from our unconscious survivalist instincts.