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STRESS

STRESS. Stress (ambiguous term): The event : A threat (real or implied) to homeostasis (often called a stressor) The response : the physiological response to the threat The condition: the physiological state that results Stressors Physiological stress Physical stress

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STRESS

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  1. STRESS • Stress (ambiguous term): • The event: A threat (real or implied) to homeostasis (often called a stressor) • The response: the physiological response to the threat • The condition: the physiological state that results • Stressors • Physiological stress • Physical stress • Emotional stress

  2. Phases of the stress response • Time frame of hormonal response • Modulation of the Stress Response • Energetics, Homeostasis and Stress

  3. Phases of the stress response • Alarm Phase • Resistance Phase • Exhaustion Phase

  4. Sympathetic Neuron Releases norepineprhine onto these tissues Adrenal Gland epinephrine Alarm Phase:Catecholamines: epinephrine and norepineprhine

  5. Epinephrine and Stress

  6. Catecholamines--what do they do? • Increase blood glucose levels • Increase oxygen in circulation • Increase heart rate • Alters blood supply— ↑ to brain and muscles

  7. Phases of the stress response • Alarm Phase • Resistance Phase • Exhaustion Phase

  8. STRESS hypothalamus pituitary adrenal Glucocorticoids (cortisol, corticosterone)

  9. Common Diving Petrel near the South Georgia Islands

  10. 90 Storm (n=8) 80 70 60 50 40 30 20 10 0 0 10 20 30 40 50 60 Calm (n=8) Pre-storm (n=3) Corticosterone, ng/ml Time after capture (min)

  11. Effects of Glucocorticoids Emergency Life History Stage • Increase circulating glucose • Suppress the immune system • Suppress reproductive behavior • Suppress growth • Multiple behavioral effects, dependent on species… • e.g. • Induce territory abandonment • Increase foraging • Reduce parental care

  12. The stress responsealarm and resistance • Maximizes glucose in the blood • Maximizes glucose and oxygen delivery to critical tissues • Shuts down non-critical activities (redirects physiology and behavior) • Digestion • Reproduction • Growth

  13. Phases of the stress response • Alarm Phase • Resistance Phase • Exhaustion Phase

  14. glucose mobilization Breakdown of protein to make glucose Inhibit immune system Decreased parental care Decrease reproduction Energy depletion Muscle wasting Increase parasite load, can’t fight disease, infection Loss of young Total loss of fitness for the season Acute Responses to Stress Chronic Stimulation

  15. Phases of the stress response • Alarm Phase • Activated in seconds • Resistance Phase • Activated in minutes • Exhaustion Phase • Chronic stimulation of Catecholamines and Glucocorticoids

  16. Phases of the stress response • Time frame of hormonal response • Modulation of the Stress Response • Energetics, Homeostasis and Stress

  17. Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Body Condition Effect of Parental Responsibility Effect of Breeding Environment

  18. Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Body Condition Effect of Parental Responsibility Effect of Breeding Environment

  19. fence lizard Corticosterone and Body Condition

  20. Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Body Condition Effect of Parental Responsibility Effect of Breeding Environment

  21. Males 80 Females 60 40 20 11 9 8 13 8 5 0 PESA SESA WESA REPH F Parental care? : M M + F Corticosterone Increase, ng/ml Magnitude of Pectoral Semipalmated Red Sandpiper Sandpiper Phalarope

  22. Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Body Condition Effect of Parental Responsibility Effect of Breeding Environment

  23. Breeding Environment

  24. 60 Abert's Towhee 50 50 Cactus Wren 40 summer summer 40 40 winter summer Inca Dove winter 30 30 30 20 20 20 10 10 10 0 0 0 CORT (ng/ml) 1 5 10 30 60 1 5 10 30 60 1 5 10 30 60 Black-throated sparrow 50 winter 40 30 20 10 0 1 5 10 30 60 Time after capture (mintues) BENIGN BREEDING ENVIRONMENT HARSH BREEDING ENVIRONMENT

  25. Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Body Condition Effect of Parental Responsibility Effect of Breeding Environment

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