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

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. hypothalamus pituitary adrenal Glucocorticoids (cortisol, corticosterone

9. Common Diving Petrel near the South Georgia Islands

10. 6050403020100 0 20 30 40 50 60 70 80 90 Pre-storm (n=3) Storm (n=8) Calm (n=8) Time after capture (min) Corticosterone, ng/ml

11. Effects of Glucocorticoids 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 Emergency Life History Stage

12. The stress response alarm 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 StressChronic 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 Breeding Environment Effect of Parental Responsibility Effect of Body Condition

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

19. Corticosterone and Body Condition fence lizard

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

21. PESASESAWESAREPH 0 20 40 60 80 Males Females Magnitude ofCorticosterone Increase, ng/ml Pectoral Sandpiper Semipalmated Sandpiper Red Phalarope 98 11 13 85 F M + F MParental care? :

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

23. Breeding Environment

24. Time after capture (mintues) CORT (ng/ml) BENIGN BREEDING ENVIRONMENT HARSH BREEDING ENVIRONMENT 15103060 winter 0 10 20 30 40 50 60 summer 15103060 0 10 20 30 40 50 summer winter Cactus Wren Black-throated sparrow 15103060 0 10 20 30 40 50 Abert's Towhee 15103060 0 10 20 30 40 summer winter Inca Dove

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

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 E E = The energy required to maintain homeostasis (basic existence) E I = The energy required to maintain normal function under ideal conditions E O = extra energy required under non- ideal conditions E G = Energy available in the environment

29. EIEI E ENERGY TIME E I = normal function—ideal conditions regulated homeostasis E E = basic existencehomeostasis E O = function—non-ideal conditions facultative homeostasis Energy Model homeostasis Regulated homeostasis Facultative Homeostasis

30. EIEI E ENERGY TIME E I = normal function—ideal conditions regulated homeostasis E E = basic existencehomeostasis E O = function—non-ideal conditions facultative homeostasis Energy Model homeostasis Regulated Homeostasis Facultative Homeostasis

31. EiEi E ENERGY TIME EGEG E G = energy available E i = normal function—ideal conditions regulated homeostasis E E = basic existencehomeostasis E O = function—non-ideal conditions facultative homeostasis Energy Model homeostasis Regulated Homeostasis Facultative Homeostasis Negative Energy Balance ELHS

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

33. EGEG EIEI E EOEO EGEG EIEI E EOEO Energy Models ENERGY