Homeostasis

• What is homeostasis?

  Maintaining a stable internal environment despite changing conditions
• Why is homeostasis important?

  It keeps conditions constant for enzyme action and cell functions
• Homeostasis includes the control of:

  • body temperature
  • glucose levels
  • water and ion levels
• What are internal conditions?

  Conditions inside the body which we have to maintain within certain levels to stay healthy
• Examples of internal conditions:

  • blood glucose concentration
  • blood pH
• True or false? Homeostasis ensure internal conditions stay exactly constant, they don't fluctuate at all. 

  False
• What are external conditions?

  Conditions outside the body
• Examples of external conditions:

  • amount of fluids you drink
  • room temperature
• Homeostasis relies on automatic control systems. 

  In what order are signals passed along the control system? 

  receptor ➔ coordination centre ➔ effector
• What is the role of a receptor? 

  Detects (stimuli) changes in the internal or external environment 
• What is the role of a coordination centre? 

  Interprets changes and organises a response 
• Where are the coordination centres located in the body?

  • brain
  • spinal cord
  • pancreas
• Name the two types of effectors and state what they do when stimulated:

  • The two types of effectors are muscles and glands. 
  • Muscles contract
  • Glands release hormones
• Which system acts more generally across the body, the nervous system or the endocrine system?

  The endocrine system acts more generally as it involves releasing hormones into the blood stream which means they spread throughout the entire body. 
• What system does homeostasis rely on?

  Negative feedback: whenever the levels of something get too high/low, negative feedback responds to this and reverses the change
• If our body temperature gets too high, what will negative feedback cause our temperature to do?

  Decrease back down- negative feedback reverses changes
• How does negative feedback work?

  Any change in a system causes an action that reverses the change
• Role of effectors:

  Carry out a response to restore optimum conditions
• What type of feedback does homeostasis depend on?

  Negative feedback
• What is the difference between internal and external conditions?

  • internal = conditions INSIDE the body e.g. body temperature
  • external = conditions OUTSIDE the body e.g. room temperature
• What is the endocrine system?

  • made up of glands that release hormones
  • hormones act as chemical messengers that allow communication throughout the body
• What type of signals do the nervous and endocrine systems use?

  • Nervous system: Electrical (chemical at synapse)
  • Endocrine system: Chemical
• How are signals transmitted in the nervous and endocrine systems?

  • Nervous system: Through nerve cells
  • Endocrine system: Through the bloodstream
• What are the effectors in the nervous and endocrine systems?

  • Nervous system: Muscles or glands
  • Endocrine system: Target cells in specific tissues
• What type of response do the nervous and endocrine systems produce?

  • Nervous system: Muscle contraction or secretion
  • Endocrine system: Chemical change
• How do the speed and duration of response compare between the nervous and endocrine systems?

  • Nervous system: Rapid response, short duration
  • Endocrine system: Slower response, long duration