Module 1

Animal physiology: The study of how animals work (function)

• integrated function

Aristotle

• emphasized the relationship between structure and function

• groups organisms into blood/no-blood

• speculated on body function

Erasistratus

• father of physiology

• applied physics laws to study human function

• suggested the heart was a pump

• named cardiac tricuspid valve

Galen

• accomplished physiologist of antiquity

• used systematic experiments to determine the function

Ibn al-Nafis

• correctly described pulmonary circulation, heart anatomy, coronary circulation

• confirmed the heart was a pump

William Harvey

• completed the description of circulatory system and properties of blood

• discovered that the heart powered blood movements

• speculated that capillaries must exist (closed circulatory system)

Antoine Lavoiser

• identified oxygen and hydrogen

• role of oxygen in combustion and aerobic metabolism

Claude Bernard

• suggested ‘blind’ experiments

• hemoglobin carries oxygen, nerves can regulate blood flow

• named Millieu interieur: the conditions inside your body are very different from the outside

Walter Cannon

• fight or flight response

• discovered homeostasis

• dry mouth hypothesis: regulates thirst

The August Krogh Principle: for every biological problem there is an animal on which it can most conveniently be studied

Metazoan

• an animal

• eukaryotes and multicellular

• but not all eukaryotes are multicellular

What are the selective advantages of evolving multicellularity?

• exposure to changing environment (can adapt to different pH, temperature, oxygen availability, food sources) - for a single cell, it has direct interaction with the environment (heavily influenced)

• homeostasis defense maintenance

• more cells = bigger size

• more control over the internal environment (digesting large meals, metabolites, ions, temperature, microbiome)

• size and temperature impact physiological function

• permits divisions of cell types, tissues, organs, and organ systems

Functions of volume

• metabolic rate (greater volume of cells = more energy metabolism)

• heat production (end product of metabolic processes)

Functions of surface area

• respiration

• absorption, expulsion

• the bigger you are, the more you can exchange with the environment

• heat loss to environment is surface-area based

Volume increases faster than surface area. If resting animals had a similar metabolic rate, larger animals will have less and less heat loss for more heat production.

Colonial Choanoflagellate

• closest living relatives to metazoans but unicellular

• found in small, simple colonies

• mono lake: inhospitable, with few species

• formed large colonies in mono lake through its ability to control multicellular organisms

• bacterial DNA inside colony lumen

• analogous to ‘microbiome’

Phenotype is a product of genotype and environment

• acclimation: in the lab, controlled variable

• acclimatization: natural variation

All animal species can utilize sexual reproduction, while only some can utilize asexual reproduction.

Sexual reproduction enables genetic variation for climate/ecosystem changes.

Asexual genes make clones, so all offspring are identical to parent.

Adaption: phenotype changes over time but not all phenotypic changes are a result of adaptation

Comparative Physiology works to advance veterinary medicine, conserve species, and works to advance human medicine.