Homeostasis

• Living organisms must maintain:

  • Body temperature
  • Blood glucose concentration
  • Blood saturation
• Homeostasis is the maintenance of a constant internal environment within an organism
• Principles of Homeostasis include maintaining:

  • Water potential of blood
  • Blood pressure
  • CO₂ concentration without complication
• Endocrine system:

  • Ensures constant internal conditions are maintained
  • Constant temperature provides an optimum environment where enzymes do not denature, and metabolic reactions can occur
• If water levels are imbalanced, it could lead to different pressures causing water to move into the cell, potentially leading to bursting
• A constant temperature is important for communication using hormones and to prevent cells from losing water and entering a hypertonic state, causing them to shrivel up
• Hormones can cause 3 main effects on their target:

  • Effects the permeability of the cell membrane
  • Negative feedback:
  • Transcription → diffuse into the cell to promote or inhibit transcription
  • Secondary messenger inside cell (relaying info)
  • Positive feedback:
  • Optimum conditions response
  • Effector reacts to increase the change
  • Receptor detects change and communication system informs effector
• Positive feedback is where a change in stimuli gives a further change, amplifying a useful stimulus to produce the desired effect; not useful stimuli cannot be controlled, e.g., hyper / hypothermia