Chapter 7 Summary

Chapter 7.1

• Every organism needs to maintain homeostasis (steady state) in some way so that its cells can function well.
• Stress can be defined in many ways, but we will mostly use the definition of stress as a deviation from homeostasis.
• Many organisms have a stress response, which allows them to return to homeostasis following exposure to a stressor.
• The severity of a stress depends on the intensity, duration, and frequency of stressor exposure, as well as whether multiple stressors are acting on an organism.

Chapter 7.2

• Stress tolerance is the ability of organisms to tolerate (deal with) stressful environments, which can include effective stress responses, as well as other changes to biology (e.g., before stress occurs) that minimize the impact of a stressor on the organism.
• Stress tolerance varies among species (depending on the environment each species is adapted to), and can vary over time within an individual.
• Both acclimatization (natural environments) and acclimation (controlled environments) can increase the stress tolerance of organisms.

Chapter 7.3

• We can categorize tolerance to a specific stress using strategies and mechanisms.
• Strategies involve the general “approach” to mitigating the stress, while mechanisms involve the biological processes that an organism uses to carry out the strategy.
• An organism may use many mechanisms to carry out a strategy, and these mechanisms may or may not differ from other organisms.