Physiology for Pharmacology

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General Introduction
      Human Physiology
 Study of how the human body
 Physiology = NORMAL
 Pathophysiology:
  How  physiological processes are
  altered in disease or injury.
Main Goal of Physiology.
 The   main goal is achievement of
 This is Maintaining constancy of
  internal environment.
 Dynamic consistency.
 Maintained by feedback loops.
   Definition of Homeostasis
 Homeostasis,from the Greek
 words for "same" and
 "steady," refers to any
 process that living things
 use to actively maintain
 fairly stable conditions
 necessary for survival…
Internal components of homeostasis
1. Concentration   of oxygen and carbon
2. pH of the internal environment
3. Concentration of nutrients and waste
4. Concentration of salt and other
5. Volume and pressure of extracellular fluid
         Control Systems
 Open systems are linear and have no
 feedback, such as a light switch. Closed
 Systems has two components: a sensor
 and an effector, such as a thermostat
 (sensor) and furnace (effector). Most
 physiological systems in the body use
 feedback to maintain the body's internal
        Extrinsic Control System
   Most homeostatic systems are extrinsic: they are
    controlled from outside the body. Endocrine and
    nervous systems are the major control systems in
    higher animals.
   The nervous system depends on sensors in the skin
    or sensory organs to receive stimuli and transmit a
    message to the spinal cord or brain.
   Sensory input is processed and a signal is sent to an
    effector system, such as muscles or glands, that effects
    the response to the stimulus.
    Intrinsic Control System
 Local, or intrinsic, controls usually involve
  only one organ or tissue.
 When muscles use more oxygen, and also
  produce more carbon dioxide, intrinsic
  controls cause dilation of the blood
  vessels allowing more blood into those
  active areas of the muscles.
 Eventually the vessels will return to
         Feedback Loops
 Sensor:
  Detects    deviation from set point.
 Integrating   center:
  Determines    the response.
 Effector:
  Produces    the response.
The LOOP (Negative Phase)
The LOOP (Negative Phase)
Negative Feedback Mechanisms
   Defending the set point.
   Reverse the deviation.
   Produces change in opposite direction.
Example (Insulin Injection) {Negative FB}
So, in summary… Negative FB
      Positive Feedback
 Action  of effectors amplifies the
 Is in same direction as change.
 Examples:
  Oxytocin  (parturition).
  Blood Cloting
  Voltage gated Na+ channels
         Note that… !!
 Most of body activities and
 mechanisms for homeostasis
 are (( Negative FeedBack)), few
 are (( Positive FeedBack)).
In Positive FeedBack

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