What is Stress?

1. What is Stress? www.psychlotron.org.uk • A state of physiological or psychological strain caused by adverse stimuli (physical, mental, internal or external) that tend to disturb the functioning of an organism.

2. Physiological Stress Response www.psychlotron.org.uk • Sudden and severe stress generally produces: • Increase in heart rate • Alterations in digestive activity • Skin becomes pale • Sweating increases • Muscular tremors • These responses are produced by the Hypothalamic-Pituitary-Adrenal Axis (HPAA)

3. Physiological Stress Response www.psychlotron.org.uk The stress response occurs when we are exposed to some sort of threat. It involves co-ordinated responses from a number of different systems and structures Hypothalamus Pituitary gland Sympathetic ganglia Adrenal cortex Adrenal Medulla Finish

4. The Hypothalamus www.psychlotron.org.uk The hypothalamus is in charge of the stress response. When a stress response is triggered, it sends signals to two other structures: the pituitary gland, and the sympathetic ganglia. Hypothalamus Pituitary gland Sympathetic ganglia Adrenal cortex Adrenal Medulla Finish

5. The Pituitary Gland www.psychlotron.org.uk The pituitary gland controls the glands of the endocrine system. When activated by the hypothalamus it releases ACTH, which activates the adrenal cortex. Hypothalamus Pituitary gland Sympathetic ganglia Adrenal cortex Adrenal Medulla Finish

6. The Sympathetic Ganglia www.psychlotron.org.uk The sympathetic ganglia are connected to the internal organs. When activated they affect the functioning of the lungs, heart and digestive system. They are also connected to the adrenal medulla Hypothalamus Pituitary gland Sympathetic ganglia Adrenal cortex Adrenal Medulla Finish

7. The Adrenal Cortex www.psychlotron.org.uk The adrenal cortex releases chemicals called corticosteriods. These have a number of functions including releasing stored glucose and controlling swelling after injury. Hypothalamus Pituitary gland Sympathetic ganglia Adrenal cortex Adrenal Medulla Finish

8. The Adrenal Medulla www.psychlotron.org.uk The adrenal medulla releases adrenaline. This hormone stimulates the sympathetic ganglia, keeping their activity at a high level. Hypothalamus Pituitary gland Sympathetic ganglia Adrenal cortex Adrenal Medulla Finish

9. Ready to expend energy, either by fighting or by running away Fight or Flight Response www.psychlotron.org.uk Increase oxygen intake Release stored glucose Divert resources away from digestion

10. The Fight or Flight Response www.psychlotron.org.uk • An early evolutionary adaptation that is useful in dealing with physical threats • Helps us deal with short-term problems that can be solved by fighting or running • Unfortunately, many of the threats we face in our society do not fall into these categories…