1. Chp 1 Function on the Ecological Stage

2. Animal Physiology: Study of how animals function
Importance:
For basic understanding of physiology since human are part of the animal kingdom
Important practical applications for health and disease, management
Mechanism and Origin: Physiology’s two central questions
What is the mechanism by which a function is accomplished?
How did the mechanism originate?

3. The importance of physiology
The study of mechanism: How do modern day animals carry out their functions? study or organ, cell functions and metabolism
The study of origin: Why do modern-day animals possess the mechanisms they do?  they inherited it from ancestors + it was beneficial adaptation through selection
Mechanism and adaptative significance are distinct concepts that do not imply each other: Adaptation can be achieved through different mechanisms

4. This book’s approach to physiology
Physiological mechanisms can be explain from a combination of evolutionary origin, environmental adaptations
Environmental physiology:
Mechanistic physiology: study of mechanism
Evolutionary physiology: study of evolutionary origins
Comparative physiology: compare the physiology of various groups
Environmental physiology: study of the physiological responses to changes in environment
All of these approaches are interrelated

5. Animals Molecules forming an animal are constantly changing
The structure of an animal (organ system) persists through time
The cells are exposed to the internal environment
The internal environment might be permitted to change with the external environment  conformity
The internal environment might be kept constant despite varying external environments  regulation

6. Homeostasis: internal constancy critical to maintain proper function
Claude Bernard: recognized the constancy of the internal environment
“Constancy of the internal environment is the condition for free life”
Walter Cannon ( ) – introduced the term “homeostasis = coordinated physiological processes which maintain most of the constant states in the organism”.

7. Homeostasis is critical to mammals, but it is not important for survival in some other groups
Regulation and conformity have their own advantages/disadvantages:
Regulation: Costs energy but permits cells to function in a constant internal environment despite changing external conditions
Conformity: Cells are subjected to changes when external environment changes. However, if they survive it, the energy cost is minimal.

8. Time in the lives of animals
1- physiological responses to change in external environment
2- internally programmed changes of physiology
3- evolutionary responses: at the level of populations
(1) Responses to changes:
Acute responses: responses within minutes
Chronic responses: long term changes to the physiology
Acclimation: physiological responses to small changes in the environment
Acclimatization: responses to a larger change in the environment (ex: winter and summer)

9. 2- internally programmed changes of physiology
Phenotypic plasticity: phenotypic changes that an individual (single genotype) can undergo with changing environment
Internally programmed changes: genetically programmed: can be due to development or to biological clocks
- development: Hb expression
- biological clocks:
- daily rhythm
- seasonal rhythm ..

10. The importance of body size
Size determines many functions (scaling):
- gestational time
- rate of energy use
- age of sexual maturity

11. Environments
All the chemical, physical, and biotic components of an organism’s surroundings.
Earth’s major physical and chemical environments:
Temperature: -70oC in Antarctica to 50oC in some deserts  most tissues are killed at temp>45oC
Oxygen: 21% O2 in air, less in soil, high altitude, low solubility in water
Water: universal solvent. Is the place of origin of life.
Blood of marine invertebrates has a similar composition to sea-water (SW). Osmosis effect if water salinity changes
Presence of microenvironments and microclimates
Animals modify their environments

12. Evolutionary processes
Evolutionary physiology: study of the origin and maintenance of physiological traits
Some processes are adaptive (due to natural selection), others are not (= founder effect -due to genetic drift)
Pleiotropy: when a trait is common in a population because it is closely correlated with another trait favored by selection

13. The study of adaptations
Comparative method: today animals are the products of yesterday life. We inherited the adaptations
Studies of laboratory populations over many generations
Single-generation studies of individual variation
Creation of variation for study
Study of the genetic structure of natural populations
Phylogenetic reconstruction
Evolutionary potential depends on the available genetic variation