BIO SCI 47 Chapter Notes - Chapter 12: Negative Feedback
22 May 2018
School
Department
Course
Professor
Aging and Death
Aged Organisms and Stress
● Aging can be defined as the worsening ability to deal with stress
● Most things in an aged organism work fine until something is thrown at them
● Failing to activate a stress response
○ How organs respond to stress
○ Cannot turn off stress response
■ older individuals are impaired at turning off epinephrine, norepinephrine,
or glucocorticoid secretion after a stressor has finished
● Not enough or too much stress response
● even in the absence of the stressor, epinephrine, norepinephrine, and glucocorticoid
levels are typically elevated
Salmon
● In some species glucocorticoids are cause of death
● Salmon are super gross after they spawn bc they’ve been through so much stress to be
at their reproduction spot
● When salmon spawn, regulation of their glucocorticoid secretion breaks down
○ Basically, the brain loses its ability to measure accurately the quantities of
circulating hormones and keeps sending a signal to the adrenals to secrete more
of them
■ Failure of feedback loop
● If you remove adrenals, salmon won’t do this
Chronic Stress and Aging
● Theory that you only have a certain amount of heartbeats before you die
Document Summary
Aging can be defined as the worsening ability to deal with stress. Most things in an aged organism work fine until something is thrown at them. Older individuals are impaired at turning off epinephrine, norepinephrine, or glucocorticoid secretion after a stressor has finished. Not enough or too much stress response. Even in the absence of the stressor, epinephrine, norepinephrine, and glucocorticoid levels are typically elevated. In some species glucocorticoids are cause of death. Salmon are super gross after they spawn bc they"ve been through so much stress to be at their reproduction spot. When salmon spawn, regulation of their glucocorticoid secretion breaks down. Basically, the brain loses its ability to measure accurately the quantities of circulating hormones and keeps sending a signal to the adrenals to secrete more of them. If you remove adrenals, salmon won"t do this. Theory that you only have a certain amount of heartbeats before you die.
