Chapter 1 - why don't zebras get ulcers?

Question 1

Explain the findings of Seyle’s less than trauma free rat injection study?

Answer 1

Seyle (1930’s) investigated the effects of an ovarian extract in rats.

Important: the injection procedure for both control and experimental groups of rats was traumatic; dropping them, chasing them ect. Both groups of rats developed peptic ulcers, enlarged adrenal glands, atrophy f tissues of the immune system.

This finding was further studied; putting rats into uncomfortable living environments (rood/boiler room), surgical procedures and forcing them to exercise. The physiological changes in the rats were the same as the ones in the original study.

He concluded the rats were experiencing “stress”.

Question 2

How did Selye formalize the concept of stress ?

Answer 2

1. General Adaption system/stress-response: The body has a surprisingly similar set of responses to a broad array of stressors.
2. If stressors for on for too long, they make you sick.

Question 3

Homeostasis vs. Allostasis : What are the 2 key comparisons?

Answer 3

1. Homeostasis : there is a single optimal level, number/amount for any given measure in the body.
   Allostasis: Contradicts this as; “constancy through change”; what is ideal under basal conditions changes during stress.
2. Homeostasis: This optimal level is reached through a specific local regulatory mechanism.

Allostasis: Argues that there are many various ways for the body to regulate itself, each with their own consequences.

Question 4

What does your body do to adapt to acute stressors?

Answer 4

1. Rapid mobilization of energy (glucose, simple proteins + fats) from storage sights (fat cells, liver & muscles)
2. Inhibition of immunity, further storage, digestion and other long-term projects ( growth, repair ect).
3. Perception of pain is greatly diminished/blocked.

Question 5

How did Seyle explain the rats stress induced sickness and why is this reasoning incorrect?

Answer 5

3rd stage “exhaustion”: Stores that secrete hormones during the stress-response become depleted - there is no energy for defense left.

Fault in reasoning: It is very are for the crucial hormones to be depleted even through sustained stress. In actuality, the stress-response can become more damaging then the stressor itself because of the stress-response inhibiting actor (repressed immunity, growth, rest ect).

Question 6

Doe stress increase the risk of getting sick?

Answer 6

No, stress increases the risk of obtaining diseases that make you sick. Stress is not what causes disease directly but rather what weakens the bodies’ defenses to these diseases.