Intro Definitions

• Feedfoward regulation


  A Change in a variable is anticipated and a response is evoked to minimize fluctuations in the variable eg. Central command at the onset of exercise
• Feedback types

  Positive feedback: accelerates a process by moving a variable further from a set point eg. oxytocin during birth (make a change bigger) Negative feedback: minimizes changes from the set point of a system, leading to stability eg. Blood sugar regulation (makes change smaller)
• Feedforward systems


  Anticipate a change and elicit a response before it happens
• Feedback systems


  Respond to a change after it has occurred
• 5 parts of homeostasis

  1. Stimulus: produces change in variable

  2. Receptor: detects change

  3. Input: information is sent along afferent pathway to control center

  4. Output: information is sent along efferent pathway to effector

  5. Response: of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level
• Reference values


  Often presented as "normal ranges", available for many physiological measures (i.e. heart rate)
• Steady state


  A state in which a variable in a system is not changing, but energy must be continuously added a maintain a stable, homeostatic condition
• Equilibrium


  A state where the variable does not require an input of energy to maintain constancy
• Dynamic constancy


  A given variable may fluctuate in the body in the short term but is stable and predictable in the long term
• Homeostasis


  The dynamic process of maintaining a stable internal environment
• General principals of physiology (3 important)

  Homeostasis is essential for health and survival- there is a necessity to maintain physiological variable within normal ranges Physiological processes are dictated by the laws of physics and chemistry

  Structure is a determinant of (and has coevolved with) function
• Levels of physiology 3

  Cellular: the study of cellular functioning

  Systemic: the study of how whole organ systems

  Pathophysiology: the study of disease states and their effect on function
• Anatomy vs physiology


  Structure (anatomy) dictates function (physiology)
• Physiology


  The study of how living organisms' function and the mechanisms involved Homeostasis is a defining feature of physiology
• Anatomy


  The study of the physical structure and shape of the body and its components Gross anatomy vs. Microscopic