BMSC 207 (Study notes)

• Physiology


  The study of the normal functions of a living organism and its component parts, including all chemical and physical processes
• Physiology


  • The term physiology literally means knowledge of nature
  • Aristotle used the word in this broad sense to describe the functioning of all living organisms, not just the human body
  • Aristotle is the father of medicine
• Emergent properties


  Properties that cannot be predicted that exist based only on knowledge of the system's individual components
• Emergent properties result from complex, nonlinear interactions of the different components
• Emergent properties in humans

  • Emotion
  • Intelligence
  • Other aspects of brain function
• None of the emergent properties can be predicted from knowing the individual properties of nerve cells
• Physiology is an integrative science
• To integrate


  To bring varied elements together to create a unified whole
• Physiology is closely tied to anatomy

  The structure of a cell, tissue, or organ must provide a physical base for its function
• Levels of organization


  • Molecules
  • Cells
  • Tissues
  • Organs
  • Organ systems
• Cells are the smallest unit of structure capable of carrying out life processes
• There are 4 main categories of cells in the body
• Tissue


  A collection of cells carrying out related functions
• Organ


  The formation of tissues into a structural and functional unit
• Organ system


  Integrated groups of organs
• It is common to study each organ system individually but there is much integration between many of the organ systems
• The nervous system is in charge of all the other systems
• The musculoskeletal system is also important because in each function and organ there is a muscle group used
• The circulatory system is also a big important part of the human body
• Teleological approach


  Describing physiological processes by their purpose rather than their mechanism
• Mechanism


  A physiological process or "how" of a system
• Physiologists and physiology often focus more on a mechanistic approach than the function
• Homeostasis


  The ability to maintain a relatively stable internal environment in spite of exposure to external variability
• Homeostasis and regulation of the internal environment are key principles in physiology
• Walter B. Cannon


  Wrote a review for the American Physiological Society and coined the term homeostasis in 1929
• Homeo


  Like or similar (range of values)
• Stasis


  Condition (not a static state)
• Some physiologists contend that a literal interpretation of stasis - a state of standing - in the word homeostasis implies a static, unchanging state, and argue that we should use the word homeodynamics instead

  
• Variables under homeostatic control

  • Blood pressure
  • Body temperature
  • Ion/molecule concentration
  • Gas partial pressures
• External changes that can disrupt homeostasis

  • Toxic chemicals
  • Physical trauma
  • Foreign invaders (bacteria or viruses)
• Internal changes that can disrupt homeostasis

  • Abnormal cell growth
  • Autoimmune disorder
  • Genetic disorders
• If the body fails to maintain homeostasis of critical variables, normal function is disrupted in a disease state or pathological condition
• Internal environment of the body

  Extracellular fluid (ECF) surrounding cells, a buffer between cells and the external environment

  
• Dynamic steady state


  Materials constantly moving back and forth
• Claude Bernard wrote of the "constancy of the internal environment"
• Most cells in our bodies are not very tolerant of changes in their surroundings
• Many marine organisms relied on the constancy of their external environments to keep their internal environment in balance
• As organisms evolved and migrated, they encountered highly variable external environments
• The internal environment of the body for multicellular animals is the extracellular fluid that surrounds the cells, a "sea within" the body
• Extracellular fluid serves as the transition between an organism's internal environment in the intracellular fluid inside the cells