Acute Stress Flashcards
(12 cards)
What is the acute stress response and why is it considered adaptive?
It is a rapid physiological reaction to threat (fight-or-flight) that mobilise energy and enhances survival by preparing the body for immediate action, such as escaping or defending.
Which systems mediate the acute stress response in mammals?
The hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic division of the autonomic nervous system leading to the release of glucocorticoids (adrenal cortex) and catecholamines (adrenal medulla)
What are the main physiologic changes caused by the acute stress response in mammals?
Increased heart rate, increased blood glucose, redirected blood flow, suppressed digestion and reproduction, heightened alertness
What is the equivalent stress pathway in fish?
The hypothalamus-pituitary-interreneal (HPI) axis, which leads to the release of cortisol Iinterreneal tissue) and catecholamines (chromaffin cells)
What similarities exist between the stress response of fish and mammals?
Both use cortisol and catecholamines to mobilise energy, increase alertness, and enhance locomotory ability in response to threats
How do the endocrine structures differ between fish and mammals in stress response?
Mammals have adrenal glands with a distinct cortex and medulla; fish lack discrete adrenal glands and instead use interreneal and chromaffin cells dispersed near the kidney.
What additional system contributes to the mammalian stress response, but is less developed in fish?
The sympathetic nervous system, which allows mammals finer control of cariodvascular and other responses
What are the short-term benefits of the acute stress response in both fish and mammals?
Increased chances of surviving by enhancing energy availability, muscle performance, and sensory alertness to escape or counter threats.
What are the long-term physiological costs of the acute stress response in fish?
Suppressed immunity, impaired growth, reduced reproductive success, and poor osmoregulation.
What are the long-term physiological costs of the acute stress response in mammals?
Suppressed immune function, reduced growth and reproductive output, oxidative stress, and risks of chronic diseases like heart disease and depression.
Why is the acute stress response considered a trade-off?
It prioritises short-term survival over long-term functions like growth and reproduction, which can be costly if the response is frequent or prolonged
What does the similarity of stress responses in fish and mammals suggest about evolution?
That the acute stress response is an evolutionary conserved mechanism, indicating strong selection for its survival advantage across vertebrates.
