STRESS

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

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

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

27. Energy and Homeostasis: Definitions • Homeostasis: maintenance of basic systems essential for life: pH, glucose, temp, salts, oxygen • But: homeostasis must be supported as environmental conditions or life history stage changes……SO: • Basic—maintenance of basic systems • Regulated— homeostasis through life history changes • Facultative— homeostasis under non-ideal conditions or unpredictable changes • Stress: when energy required to maintain homeostasis is greater than the energy available (negative energy balance)

28. Energy • EE = The energy required to maintain homeostasis (basic existence) • EI = The energy required to maintain normal function under ideal conditions • EO = extra energy required under non-ideal conditions • EG = Energy available in the environment

29. EI EE Energy Model EE = basic existence homeostasis EI = normal function—ideal conditions regulated homeostasis EO = function—non-ideal conditions facultative homeostasis ENERGY Facultative Homeostasis Regulated homeostasis homeostasis TIME

30. Energy Model EE = basic existence homeostasis EI = normal function—ideal conditions regulated homeostasis EO = function—non-ideal conditions facultative homeostasis ENERGY Facultative Homeostasis EI Regulated Homeostasis EE homeostasis TIME

31. EG = energy available EG ELHS Energy Model EE = basic existence homeostasis Ei = normal function—ideal conditions regulated homeostasis EO = function—non-ideal conditions facultative homeostasis Negative Energy Balance ENERGY Facultative Homeostasis Ei Regulated Homeostasis EE homeostasis TIME

32. EO EE = basic existence Energy Model Ei = normal function—ideal conditions EO = function—non-ideal conditions EG = energy available Negative Energy Balance EG ENERGY Facultative Homeostasis Ei Regulated Homeostasis ● seasonal change ● breeding ● predator pressure ● parasite load ● human disturbance ● change in social status ● change in energetic reserves EE homeostasis Time to change strategy (ELHS) TIME

33. EG EG EI EI EE EE EO EO Energy Models ENERGY