stress Flashcards
define stress
An environmental effect on an individual which over-taxes it’s control systems & reduces its fitness
Unfavorable state being brought on by unpleasant or harmful conditions
Environmental conditions having adverse effect on an individual
stressors lead to symptomatic physiological changes, what is an example?
hormone response pattern
what kind of hormones indicate stress?
adrenal hormones
how are animals affected by stress in terms of environment?
Distinguish situations which are adverse & those that are not
how does an animal cope by regulatory systems from an affected environmental conditions?
adaptation
what is fundamentally different from situation in which environment has detrimental consequences?
adaptation
describe detrimental
How to assess
define fitness of genotype
Measured as being per capita rate of ↑ of corresponding phenotype
provide examples of fitness of phenotype in the environment
◼ Age at 1st breeding
◼ Interval between successive breedings
◼ Survivorship from birth to 1st breeding
◼ Survivorship of adults between successive breedings
◼ Number of female offspring / breeding attempt
Fitness reduced if any of these adversely affected:
◼ Delayed breeding
◼ Mortality
◼ Reduced number of offspring
what stress response system is responsible for fight or flight system?
Hypothalamic-adrenal-medullary stress response system
Why is Walter Cannon important?
◼ Identified hormone secreted by adrenal glands
◼ Response to physiological stimuli
◼ Prepares & supports body in fight/flight situations
what is secreted when cats in cages are scared by barking dogs?
Secrete adrenaline (epinephrine)
what are some human examples of epinephrine release?
◼ Taking exam
◼ Cheering at ball game
what is epinephrine and norepinephrine associated with and what’s the difference between them?
◼ High anxiety/Activity
epinephrine: More effect on heart
norepinephrine: More effect on blood vessels
the 4 “E” (epinephrine) situations
exercise
excitement
embarrassment
emergency
how does the sympathetic alarm reaction affect the animal?
Animal must decide almost immediately whether to stand or run
what is the alarm reaction?
Make’s animal’s subsequent reactions vigorous
mass sympathetic discharge increases in:
◼ ↑ arterial pressure & HR ◼ ↑ blood flow to active muscles concurrent with ↓ blood flow to GI tract organs ◼ ↑ rate of cellular metabolism ◼ ↑ blood glucose concentration ◼ ↑ muscle & liver glycolysis ◼ ↑ muscle strength ◼ ↑ mental activity
examples of parasympathetic responses
- stimulates flow of saliva
- slows heartbeat
- constricts bronchi
- stimulates peristalsis and secretion
- stimulates the release of bile
- constricts bladder
parasympathetic system’s sludd:
salivation lacrimation urination digestion defecation
examples of sympathetic responses
- dilates pupil
- inhibits flow of saliva
- accelerates heartbeat
- dilates bronchi
- inhibits peristalsis and secretion
- conversion of glycogen to glucose
- secretion of adrenaline and noradrenaline
- inhibits bladder contraction
describe the fight or flight response starting with the hypothalamus (flow chart)
hypothalamus activates the adrenal-cortical system by releasing CFR, then the pituitary gland secretes ACTH and the ACTH arrives at the adrenal cortex and releases ~ 30 hormones which is released into the bloodstream and neural activity combines with hormones in the bloodstream by constituting fight or flight response
hypothalamus activates the sympathetic nervous system where impulses activate glands and smooth muscles and neural activity combines with hormones in the bloodstream by constituting fight or flight response
the sympathetic nervous system can also activate the adrenal medulla where it can release norepinephrine or epinephrine into the bloodstream and neural activity combines with hormones in the bloodstream by constituting fight or flight response
why is Hans Selye important?
◼ General concept of
stress developed
◼ Medical student (1936)
Injected tissue extracts in rats -produced triad of symptoms
