The following activity includes an interactive animation that will help you to appreciate the nature of stress and the role played by stress and the hypothalamic–pituitary–adrenal (HPA) axis when we come to consider the aetiology of emotional disorders such as depression and anxiety.
The animation is designed to help you understand the operation of the HPA axis – how it is controlled under normal conditions and how the controls are disrupted under conditions of chronic stress.
Allow 1 hour
The stress response has evolved to mobilise the body and mind for action when a threat is perceived. The response has two main strands which act in parallel. The first is the sympathetic response, which triggers the release of adrenalin from the medulla of the adrenal gland. The second strand involves the hypothalamic–pituitary–adrenal, or HPA, axis, and triggers the release of cortisol from the cortex of the adrenal gland.
In this activity you will look at the operation and control of the HPA axis in three different conditions – first, under normal relaxed or baseline conditions; second, under normal conditions when there is an episode of stress which is resolved; and third, under conditions of continual or chronic stress when regulation of the HPA axis breaks down.
Baseline
Acute
Chronic
Identify two factors from the list below that would help to bring cortisol levels back to baseline levels after experiencing a stressful event.
Identify the correct statements about cortisol from the following:
Cortisol acts via glucocorticoid receptors to inhibit the activity of the HPA axis, so less cortisol is secreted. Why does cortisol become less effective in inhibiting the HPA axis during chronic stress? Select the best explanation from the list below.
Statement (a) provides the best explanation for why cortisol becomes less effective in inhibiting the HPA axis during chronic stress. Statement (b) is incorrect because there is more, not less, cortisol present during chronic stress. Statement (c) is correct in that there is more activity in the HPA axis during chronic stress, but it does not explain why cortisol fails to control the activity of the HPA axis.
Select, from the following, the statement(s) that explain why the high activity of the HPA axis during chronic stress can affect how we feel and act.
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