HOMEMOSTASIS

• Homeostasis is the maintenance of a stable internal environment.
• homeostasis is about the regulation of the conditions inside your body (and cells) to maintain a stable internal environment; in response to changes of internal and external conditions
• nervous and hormonal systems are automatic control systems that regulate your internal environment
• E.g. there are control systems that maintain your body temperature, blood glucose level and your water content
• 3 main components of the automatic control system:

  • RECEPTORS
  • COORDINATION CENTRES (the brain, spinal cord and pancreas)
  • EFFECTORS
• negative feedback counteracts changes
• Your automatic control system keeps your internal environment stable by a mechanism called NEGATIVE FEEDBACK
• E.g. when the level of something (e.g water or glucose) gets too high or too low, your body uses negative feedback to bring it back to normal
• when levels are TOO HIGH:

  • RECEPTORS detect a STIMULUS (a stimulus is a change in the environment)
  • The COORDINATION CENTRE receives and process the information, then organises a response
  • EFFECTOR produces a response, which counteracts the chang and restores the optimum level
  • The levels then DECREASE
• when levels are TOO LOW

  • RECEPTOR detects a stimulus
  • The COORDINATION CENTRE receives and processes the information, then organises a response
  • EFFECTOR produces a response , which counteracts the change and restores the optimum level
  • The level INCREASES
• 3 main components of the automatic control system:

  1. RECEPTORS (cells hat detect stimuli (change in environment))
  2. COORDINATIOM CENTRE (the brain, spinal cord and pancreas)
  3. EFFECTORS (muscles or glands which bring about responses - restore optimum levels)
• The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream.

  • The blood carries the hormone to a target organ where it produces an effect.
• Compared to the nervous system the effects from the endocrine system are slower but act for longer.
• blood glucose concentration = the amount of sugar in your bloodstream
• blood glucose is also a controlled part of homeostasis
• WHAT INCREASES BLOOD GLUCOSE LEVELS?

  Eating food containing carbohydrates
• WHEN BLOOD GLUCOSE LEVEL IS TOO HIGH?

  wen blood glucose levels are too high it it detected by the pancreas. The pancreas then produces insulin which is absorbed into the bloodstream. The insulin binds to receptors on certain cells in the liver and muscle that will take in extra glucose molecules from the bloodstream and convert them into glycogen which is a long term sorage for glucose molecules. The blood glucose level ill then decrease
• WHEN BLOOD GLUCOSE LEVEL IS TOO LOW?

  When blood glucose levels are low it is detected by the pancreas which will produce the hormone GLUCAGON into the bloodstream. This hormone travels around the body and mainly bind to the cells in the liver. This stimulates the liver to break down the stored glycogen into glucose and release it into the blood. The extra glucose increases blood glucose levels back to normal. This is called negative feedback
• TYPE 1 DIABETES:

  • when the pancreas produces little to no insulin
  • a persons blood glucose level can rise to a level that can kill them
  • they need to inject themselves with insulin (most likely at meal time - so glucose is removed quickly once the food is digested)
  • avoid/limit intake of carbohydrate rich food e.g. sugar
  • regular exercise (helps remove excess glucose)
• TYPE 2 DIABETES:

  • person becomes resistant to own insulin (they still produce insulin but their body's cells don't respond to the hormone)
  • persons blood sugar level can rise to a dangerous level
  • being overweight can increase chances of developing type 2 diabetes
  • type 2 diabetes can be controlled by eating a carbohydrate-controlled diet
  • getting regular exercise