Homeostasis and physiological measures

• Homeostasis = Is the technical term for the process of maintaining a constant internal environment.

  • The conditions within the body
  • The tendency to maintain stability while adjusting to conditions.
  • To drive the body's physiological functions at the right pace.
• Which parameters in the human body are kept ‘constant’?

  • pH​
  • Water ​
  • Temperature​
  • Blood glucose
  • Iron levels​
  • Copper regulation​
  • Levels of blood gases​
  • Blood oxygen content​
  • Arterial blood pressure​
  • Calcium levels​
  • Sodium concentration​
  • Potassium concentration
• Negative Feedback loop​

  • Response in the opposite direction as the stimulus. Maintains homeostasis. For example temperature and water levels.
• Positive Feedback loop​

  • Response in the same direction as the stimuli. Occurs with childbirth, blood clotting, and generation of nerve signals​.
• Receptors work to amplify an effect brought about by a change.​

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  Positive feedback is a mechanism that intensifies a change in the body’s​physiological condition rather than reversing it (as a negative feedback mechanism does).
• What is the afferent pathway?

  Afferent neurons carry information from sensory receptors found all over the body towards the central nervous system.
• What is the control centre?

  The body structure that analyses the input, determines the appropriate response (set point), and activates the effector. The hypothalamus is the region of the brain that is the control centre of homeostasis.
• What are effectors?

  The component in a feedback system that causes a change to reverse the situation and return the value to the normal range e.g. muscles, glands, and organs.
• Examples of responses:

  Sweat glands (effectors) release sweat to lower body temperature. Liver (effectors) release glucose to raise blood glucose levels.
• What is meant by 'set point'?

  A set point is the physiological value around which the normal range fluctuates. A normal range is the restricted set of values that is optimally healthful and stable.
• What are receptors?

  Components of the control systems that detect changes e.g. nerve endings in the skin or olfactory receptors in the nose.
• Stimulus - A disruption to the internal environment usually resulting from changes in external conditions.