Adapting To Arctic Weather And Preparing For Migration Flashcards
What is a stress response?
The body’s adaptations to correct a disruption of physiological balance
What are the long term and short term responses?
- Fight or flight: adrenaline- short term
2. General adaptation syndrome: glucocorticoids- long term
What are the processes of the adrenal axis (HPA axis)?
- Brain
- Hypothalamus: CRF released into a specialised neural network to take it to pituitary gland
- Pituitary: stimulated by CRF to produce hormone ACTH which circulates in the blood
- Blood: ACTH binds to the adrenal cortex
- Adrenal cortex: cells are stimulated to produce glucocorticoids
What are the short term effects of glucocorticoids in animals?
Suppression of reproductive behaviour without affective reproductive system
Altered immune function
Increased gluconeogenesis
Increased foraging behaviour
Promotion of escape behaviour during the day
Promotion of night restfulness
What are the long term effects of glucocorticoids in animals?
Inhibition of the reproductive system Immune suppression Loss of protein from skeletal muscle Accelerated neuronal degeneration Suppression of growth
Describe the ‘capture, handling and restraint’ method to determine stress responsiveness in wild birds:
- Take blood sample within 2 mins of capture
- Birds subjected to standardised stressor (drawstring bag)
- Take further samples at defined intervals
What is the most efficient store of energy for migratory birds flying long distances?
Energy in the form of lipids (fats)
Why are lipids good energy stores?
They have a higher energy density and have little water associated with them
Can store a lot of energy in a small space
What is the highest percentage of fat found in a migratory bird?
50%
Ruby throated hummingbird
What is spring migratory fattening induced by?
Photoperiod- long days
Give an example of natural fasting in animals
When hens are incubating their eggs they lose interest in food to spend more time sitting on the eggs
What are the two effects of corticosterone?
- Basal (non stressed) concentrations regulate food intake and fat deposition
- Stress induced corticosterone secretion is associated with activating the emergency life history stage