homeostatis and nervous system

• What is homeostasis? 


  Maintaining a stable internal environment despite changing conditions 
• Why does the body need to maintain optimal conditions?

  For optimal enzyme action and cell function
• Internal conditions refers to the conditions inside the body which we have to maintain within certain levels to stay healthy. 
• External conditions refers to the conditions outside the body.
• Homeostasis relies on automatic control systems. 

  receptor ➔ coordination centre ➔ effector
•  receptor

  Detects changes in the internal or external environment 

  neurons that carry info as electrical impulses from the receptors to the CNS
•  coordination centre(CNS)

  Interprets changes and organises a response 

  connected to the rest of the body by sensory neurones and motor neuones
• effector


  Carries out the response 
• Where are the coordination centres located in the body?

  spinal cord

  brain
• Name the two types of effectors and state what they do

  The two types of effectors are muscles and glands. 

  Muscles contract when stimulated, whilst glands release hormones. 
• The nervous system is much faster than the endocrine acting as it relies on electrical impulses that can travel very quickly. 
• The endocrine system acts more generally as it involves releasing hormones into the blood stream which means they spread throughout the entire body. 
• Homeostasis relies on a system of negative feedback, meaning whenever the levels of something get too high they're brought back down, and whenever the levels of something get too low, they're brought back up. 
• homeostatis does not always ensure iternal coniditions stay exactly constant as they do flunctuate
• motor neurones


  neurones that carry electrical impulses from the CNS to effectors