Stress and Health
•What is a stressor?
•Anything that throws body out of allostatic balance
•What is allostasis?
o –Allostasis: range of measures appropriate for situation (sleep vs. bungee-jumping)
o the process of achieving stability, or homeostasis, through physiological or
o –Compare to homeostasis (maintenance of a single optimal level)
o Homeostasis is the regulation of the body to a balance, by single point tuning such as blood
oxygen level, blood glucose or blood pH. For example, if a person walking in the desert is
hot, the body will sweat and they will quickly become dehydrated. Allostasis is adaptation but
in regard to a more dynamic balance. In dehydration, sweat occurs as only a small part of
the process with many other systems also adapting their functioning, both to reduce water
use and to support the variety of other systems that are changing to aid this. In this case,
kidneys may reduce urine output, mucous membrane in the mouth, nose and eyes may dry
out; urine and sweat output will decrease; the release of arginine vasopressin (AVP) will
increase; and veins and arteries will constrict to maintain blood pressure with a smaller blood
•What are the 3 stages of a stress response?
o •The body’s attempt to restore balance.
o •Non-specific response of body to any demand made on it
o –Good stress and bad stress; Bad stress is worse for health
o •It’s great for dealing with acute physical stressors, but can be disastrous if activated all
o •Three stages:
o 1. Alarm: SNS activation
o 2. Resistance: decreased SNS activity; increased HPA activity cortisol & other
hormones for maintaining prolonged alertness & increased immune function (to
fight infections & to heal wounds)
o 3. Exhaustion: NS and Immune system are spent…person is tired, inactive, and
vulnerable to illness
•What is the role of the sympathetic NS in the stress response?
o Sympathetic NS: axons activate organs for “fight or flight”
•What is the HPA and what is it’s role in the stress response?
o •Hypothalamus, pituitary gland, adrenal cortex
o •Hypothalamus makes CRH Pituitary makes ACTH adrenal secretes cortisol
increase in blood sugar & metabolism
o •Activated w/ prolonged stressors
o •Beneficial in the short-term; detrimental in the long-term
o •Negative consequences of stress (like effects on learning and memory) can be induces
by stress itself, or by an injection of cortisol
o controls reactions to stress and body processes
•Why do you feel terrible during finals week?
o •Acute activation boosts the immune system, even improves memory o –Useful for escaping a predator…
o •*but* Powerful, inescapable, temporary stress body reacts like illness, w/ increased
o –Like exam week!
o –body increases production of natural killer cells (a type of white blood cell for
fighting infections) and cytokines.
o –Cytokines help fight infections, but they are also the body’s way of telling the
brain you are sick, so you have “sickness syndrome” (fever, exhaustion,
o –This also tires your immune system, so when challenged with an actual
bacterium or virus, it will be ill-equipped to handle it.
o •Questionaire re. stressful life events given cold virus stress > 1month more
likely more likely to develop cold
•What are some factors that affect the stress response?****
o Two factors largely determine individual responses to stressful situations: the way the
person perceives the situation, and the person’s general state of physical health.
•What are some effects of