Class13_Stress

Class13_Stress - What is Stress? Defining stress is harder...

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1 Neuroendocrinology of Stress What is Stress? • Defining stress is harder than it sounds – A state of threatened homeostasis – The thing responsible for the imbalance: stressor – The body’s response to the imbalance: stress- response Threat to Homeostasis • Lava from a volcano is about 700° C • Body temperature is 37 C° • Standing to close to lava for too long will disrupt homeostasis Other Sources of Stress • Predators • Food deprivation • Social conflict Outline • Biological stress responses • Acute versus chronic – Health effects • Resilience – Mice – Humans – Coping • Development Biological Responses to Stress • Hormones released from the hypothalamus trigger a cascade of hormonal responses
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2 Hypothalamic Response • The paraventricular nucleus of the hypothalamus releases C orticotropin R elasing H ormone (CRH) • In mammals CRH travels to the pituitary gland via the portal blood vessels Pituitary Response • CRH travels to the pituitary • CRH stimulates the release of A dreno c ortico t ropic h ormone into general circulation Adrenal response • Adrenal cortex releases glucocorticoids – Humans, most domestic animals: cortisol – Most rodents: corticosterone • Adrenal medula – epinephrine Negative Feedback • Indoor temperatures are regulated by negative feedback loops • Many physiological systems are regulated in a similar way + - Hypothalamus stressors CRH Pituitary ACTH Adrenal Cortex cortisol + + - - Hippocampus + - Negative Feedback • There are three ways to turn off cortisol – Inhibit ACTH release from pituitary – Inhibit CRH release from hypothalamus directly – Inhibit CRH release from hypothalamus indirectly (via hippocampus)
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Sympathetic Nervous System Response • Nerve endings release norepinephrine – Increase heart rate, respiration, blood pressure • Adrenal medulla releases epinephrine – Increase blood glucose levels Hypothalamus stressors S p i n a l C o r d norepinephrine norepinephrine Medulla epinephrine Outline • Biological stress responses • Acute versus chronic – Health effects • Resilience – Mice – Humans – Coping • Development The stress response is non-specific short-term adaptive long-term maladaptive
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Class13_Stress - What is Stress? Defining stress is harder...

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