Chapter 1 Outline
The Importance of Physiology
The Highly Integrative Nature of Physiology
Mechanism and Origin: Physiology’s Two Central Questions
- The study of mechanism: How do modern-day animals carry out their functions?
- The study of origin: Why do modern-day animals possess the mechanisms they do?
- Natural selection is a key process of evolutionary origin
- Mechanism and adaptive significance are distinct concepts that do not imply each other
This Book’s Approach to Physiology
Animals
- The structural property of an animal that persists through time is its organization
- Most cells of an animal are exposed to the internal environment, not the external environment
- The internal environment may be permitted to change when the external environment changes, or it may be kept constant
- Homeostasis in the lives of animals: Internal constancy is often critical for proper function
- BOX 1.1 Negative Feedback
- Time in the lives of animals: Physiology changes in five time frames
- BOX 1.2 The Evolution of Phenotypic Plasticity
- Size in the lives of animals: Body size is one of an animal’s most important traits
Environments
- Earth’s major physical and chemical environments
- The environment an animal occupies is often a microenvironment or microclimate
- Animals often modify their own environments
Evolutionary Processes
- Some processes of evolution are adaptive, others are not
- A trait is not an adaptation merely because it exists
- Adaptation is studied as an empirical science
- Evolutionary potential can be high or low, depending on available genetic variation