Chapter 1 Animal Physiology

Introduction to Physiological Principles Physiology “The study of how animals work” Knut Schmidt-Nielsen (1915–2007) Structure and function of various parts How these parts work together Diversity of animals due to evolution More than 1 million species live on Earth Unifying themes Apply to all physiological processes Biological Levels of Organization August Krogh Principle:” For every biological problem there is An organism on which it can be most conveniently studied. Physiological Processes Obey the Laws of Physics and Chemistry Fick’s Laws of Diffusion: Adolf Fick 1st Law: “ Substances diffuse from areas of high concentration to areas of low concentration.” Movement of substances from areas of high potential energy to areas of low potential energy Sources of potential energy: concentration gradient, voltage or electrical gradient, temperature gradient, pressure gradient Physiological Processes Obey the Laws of Physics and Chemistry Fick’s 2nd law of diffusion: “ The amount of a substance that diffuses across a surface is proportional to the area of that surface and inversely proportional to the distance across which the substance must diffuse.” Mechanical properties of a structure influence its function Electrical potentials are fundamental in the functions of neurons and muscles Temperature affects physiological processes at all levels of biological organization Body size Influences Physiological Patterns Figure 1.3 Allometric Scaling Equation: shows the relationship between body mass and metabolic rate as described by the equation y = aMb Basis for Evolution and Natural Selection Variation among individuals for specific traits Traits must be heritable Traits must increase fitness That is, must increase reproductive success Relative fitness of different genotypes depends on the environment If the environment changes, the trait may no longer be beneficial Not All Differences are Adaptations Genetic drift Random changes in the frequency of genotypes over time Independent of adaptive evolution Most common in small populations For example, forest fire resulting in founder effect Evolutionary Relationships Despite the diversity in animal form and function, there are many similarities Common evolutionary ancestors Closely related species share more features than distantly related species Understanding evolution is necessary to understanding physiological diversity Physiological Processes are Shaped by Evolution Phenotypes: Homologous or Analogous ACTIVITY: Guide Questions : Think, Pair- Share Give the systems that were working actively when you performed your activity. What is the specific role of each system in that particular activity? What generalization or conclusion can you draw based on question #1? Give examples of physiological changes in your body that you experienced during and after the activity. Why do you think those physiological changes occur? What type of feedback mechanism (Positive or Negative) did your body utilize to regulate your physiological processes? Justify your answer Physiological Regulation Strategies for coping with changing conditions Conformers – allow internal conditions to change with external conditions Regulators – maintain relatively constant internal conditions regardless of external conditions Organisms must maintain homeostasis to survive in diverse environments. Homeostasis is the maintenance of constant internal conditions ( Walter Cannon , 1929) Allostasis: process of achieving homeostasis through physiological changes ( allostatic response: short term or long term) Homeostatic imbalance – a disturbance in homeostasis resulting in disease Homeostasis Controlled by Feedback loops or Reflex Control Pathways Antagonistic Controls Feedback Mechanisms Negative feedback Includes most homeostatic control mechanisms Shuts off the original stimulus, or reduces its intensity Deviation from the set point, is made smaller or is resisted It does NOT prevent variation but maintains variation within a normal range Feedback Mechanisms Slide 1.20b Copyright © 2003 Education, Inc. publishing as Benjamin Cummings Positive feedback Increases the original stimulus to push the variable farther, causing a greater deviation from the set point. Phenotype, Genotype, and the Environment Phenotype is a product of genotype and its interaction with the environment Genotype – genetic makeup Phenotype – morphology, physiology, and behavior Phenotypic plasticity – single genotype generates more than one phenotype depending on environmental conditions as a result of developmental plasticity Phenotypic Plasticity Figure 1.5 Can be irreversible or reversible Irreversible Polyphenism Phenotypic Plasticity Reversible Acclimation – process of change in response to laboratory conditions Acclimatization – process of change in response to natural environment History of Animal Physiology Hippocrates (460–circa 377 B.C.) Father of medicine Aristotle (384–322 B.C.) Father of natural history Relationship between structure and function Claudius Galenus, “Galen” (129–circa 199) First experimental physiologist History of Animal Physiology Ibn al-Nafis (1213–1288) Anatomy of heart and lungs Jean-Francois Fernal (1497–1558) Outlined current knowledge of human health and disease Andreas Vesalius (1514–1564) First modern anatomy textbook William Harvey (1578–1657) Circulation of blood through the body by contractions of the heart History of Animal Physiology Herman Boerhaave and Albrecht von Haller (1700s) Bodily functions are a combination of chemical and physical processes Matthias Schleiden and Theodor Schwann (1838) “Cell theory” Claude Bernard (1813–1878) Milieu interieur (internal environment) Internal environment distinct from external environment Walter Cannon (1871–1945) “Homeostasis” History of Animal Physiology Per Scholander (1905–1980) Comparative physiology C. Ladd Prosser (1907–2002) Central pattern generators Knut Schmidt-Nielsen (1915–2007) Animals in harsh and unusual environments History of Animal Physiology George Bartholomew (1923–2006) Ecological physiology Peter Hochachka (1937–2002) and George Somero (1941– ) Biochemical adaptations Process that Causes Physiological Variation Developmental physiology Change as animal grows Environmental physiology Change in response to environment Evolutionary physiology Change due to natural selection