HOMEOSTASIS

• WHAT IS HOMEOSTASIS?

  • REGULATION of INTERNAL conditions to maintain OPTIMAL conditions for ENZYME action and CELL function
  • In RESPONSE to INTERNAL and EXTERNAL conditions (conditions are maintained INSIDE if the change is OUTSIDE
• Cells:

  • RESPIRATION occurs
  • ENERGY is released from GLUCOSE
  • ENZYMES need stable CONDITIONS to WORK
• Our body uses AUTOMATIC control systems:

  • They RECOGNISE changes in CONDITIONS, and send SIGNALS to REVERSE these changes
• THREE MAIN COMPONENTS OF AUTOMATIC CONTROL SYSTEMS:

  RECEPTOR -> COORDINATION centre -> EFFECTOR
• RECEPTORS:

  • DETECT changes in ENVIRONMENT (internal or EXTERNAL)
  • Changes in environment are called STIMULI
  • Send SIGNALS to the COORDINATION centre
• COORDINATION CENTRE:

  • RECEIVES and PROCESSES information
  • Examples: BRAIN, SPINAL cord, PANCREAS
  • Sends SIGNALS to EFFECTOR
• EFFECTOR:

  • Either a MUSCLE or a GLAND
  • Muscles- CONTRACT
  • Gland- secretes HORMONES
  • Effectors BRING about a RESPONSE
• THINGS THAT THE BODY REGULATES:

  • GLUCOSE concentration
  • Body TEMPERATURE
  • WATER concentration
• NEGATIVE FEEDBACK:

  • OPPOSES change
  • If levels are too HIGH or too LOW, the AUTOMATIC control system brings levels UP or DOWN through negative feedback
  • LOOP