W3 T2 P1

• Stress is an important factor involved in affective disorders.
• Part one covers the stress response, presenting stress hormones, introduces the hypothalamic pituitary adrenal axis, & how hormones work, considering the endocrine system.
• Part two covers the differences between acute and chronic stress and what happens when the stress response is dysregulated, focusing on depression.
• Part three will discuss different ways to measure some of the effects of stress.
• Stress can be generated from work or studies, public speaking or flying, lack of control, or with deadlines.
• Stress can be associated with a flight or fight response.
• The reactions occur in response to harmful events or threats to survival.
• Some stress experts are adding the word freeze, because instead of fighting or fleeing sometimes animals freeze, for example, deer in the headlights.
• A response to anything that threatens homeostasis of the organisms creates physiological and behavioral responses that attempt to reinstate an equilibrium.
• Stress can be caused by any circumstances that threaten the individual's well-being, or that the individual perceives as threatening to their well-being.
• The concept of stress has been attributed to Hans Selye, an Austrian-Canadian endocrinologist of Hungarian origin.
• Selye was nominated 17 times for the Nobel Prize in physiology or medicine between 1949 and 1953.
• Selye's nomination stemmed from his work on endocrinology and the adaptation syndrome, for his contribution to the isolation of steroid hormones, and for his formulation of stress reactions.
• Selye saw rats develop enlargement of the adrenal cortex, atrophy of the thalamus, spleen and lymph nodes, and deep bleeding ulcers in the lining of the stomach and duodenum due to ovarian extract injections.
• The same changes occurred in both control groups injected with saline alone, and rats injected with extracts of other organs.
• Selye also induced the same outcomes by placing animals on the roof in winter, and in the boiler room.
• Forced exercise or surgical procedures also generated the same outcomes.
• Therefore, Selye concluded the changes were a general response to all different stressors.

The General Adaptation Syndrome

• Selye called the general adaptation syndrome, also known as the stress response.
• Stress hormones are produced when this occurs.
• Stress hormones are glucocorticoids, derived from glucose, cortex, and steroid.
• The hormones regulate glucose metabolism, are synthesised in the adrenal cortex, and are chemically classified as steroids.
• Cortisol - the main stress hormone in humans.
• Cortisol is released into the blood after its creation in the cortex of the adrenal glands & transported around the body.
• Cortisol acts through specific receptors and almost cells contain receptors for cortisol.
• Cortisol can have lots of different actions, depending on which cells it is acting upon.
• Cortisol acts on two receptors, the mineralocorticoid receptor or MR, and the glucocorticoid receptor or GR
• The mineralocorticoid receptor has high affinity for endogenous glucocorticoids and therefore is already activated by low or basal cortisol concentrations.
• The glucocorticoid receptor has low affinity for cortisol, and is thus predominately activated by high cortisol concentrations as they occur upon stress.
• GR is a Ligand Activated Nuclear Transcription Factor.
• Upon ligand binding, or upon cortisol binding, the GR which resides in the cytoplasm in association with chaperone proteins, then translocates into the nucleus and binds to glucocorticoid response elements or GREs
• GRE's are on the DNA, and subsequently regulates gene transcription.
• Cortisol regulates gene expression and plays a role in the regulation of several physiological processes by controlling energy metabolism, maintaining electrolyte balance and blood pressure, and modulating immune responses.
• Neurons in the paraventricular nucleus PVN of the hypothalamus normally control the production of cortisol.
• Under a stressful trigger PVN secretes corticotropin releasing hormone/factor (CRH/CRF), and arginine vasopressin (AVP), which in turn stimulates the secretion of adrenocorticotropic hormone or ACTH from the anterior pituitary gland.
• ACTH travels to the adrenal glands which sit on top of the kidneys, which promotes the synthesis and the release of cortisol.
• Cortisol enables the release of stored glucose from the liver for energy while suppressing the immune system.
• Cortisol interacts with receptors present in multiple target tissues, including the HPA axis itself.
• Excessive levels of circulating cortisol signal the brain to regulate its production, known as negative feedback regulation.
• This generates feedback inhibition of secretion of ACTH from the pituitary and CRH from the hypothalamus, which ends up decreasing cortisol production.
• Hormones like Cortisol are part of the endocrine system and they work and act in different ways to neurotransmitters, which are part of the nervous system.
• Hormones are produced by glands and are secreted into circulation to be carried toward mostly distant target organs, where they start their action by interacting with receptors.
• Hormones induce responses at the protein or genetic level which takes some time and are an involuntary process.
• The nervous system responds rapidly to stimuli by sending electrical action potentials along neurons using neurotransmitters.
• The nervous system is often fast and short lived (example: removing hands when something is hot faster) than the effects that hormones have, which tend to be longer lasting.
• The body maintains a constant internal environment while also been able to respond and adapt to external events via the nervous and endocrine systems.
• When the nervous and endocrine systems fail, stress is felt.

Recent Life Changes Questionnaire or RLCQ

• A commonly used stress scale addresses the stress levels by inquiring about the presence or perception of life events during the recent past.
• The RLCQ ascertains a person's life change experiences over the past year or the past few months by using a list of common sources of stress.
• The RLCQ has five categories: work, home and family, health, personal and social, and financial.
• Each of these events has a score according to the severity.
• Add the number of life changing units, or LCU, to obtain a total score.
• A 6 month score of 300 or more, or a yearly score of 500 or more indicates high stress.
• The reaction to stress is what matters most.

Explore the physiological and behavioral responses to stress, including the roles of cortisol and the HPA axis. Learn about Selye's contributions to stress understanding and the impact of perception on stress levels. Discover the body's goal in responding to stressors.