Homeostasis

• Definition of homeostasis


  Maintaining a constant internal environment for enzyme activity
• What do you need to keep at the same levels

  glucose, water levels, co2, body temperature
• What happens if there's too much co2 in the body

  If built up it could lower the PH in the cytoplasm so enzymes would denature
• What happens if the levels of something are too high

  Enzymes denature
• Where is urea produced

  In the liver by the breakdown of amino acids
• What is the internal environment controlled by

  Nervous system and endocrine system
• Features of the nervous system

  Sends electrical chemical impulses

  very fast

  short lasting
• Features of endocrine system

  chemical/ hormonal messages

  slow

  long lasting, hormones released from glands , travels in blood
• Order of reaction


  Stimulus

  receptor

  sensory neurone

  relay neurone

  motor neurone

  effector

  response
• What is the stimulus


  the change in our environment
• What does the receptor do


  Detect things ( senses )
• What does the coordination center do and where

  processes information by the brain or spinal cord
• What does the effector do 


  Causes muscle or gland to have a response
• What do you call the tiny gap where two neurones meet

  synapses
• What's a synapse


  A tiny gap where two neurones meet
• How are the impulses able to cross

  By using chemicals released by a neurone
• What are the chemicals realised by a neurone called

  Neurotransmitters
• what parts are in the endocrine system

  Brain

  pituitary gland

  thyroid gland

  pancreas

  adrenal gland

  kidney

  ovary

  testes
• What does the thyroid gland do


  Controls activity& heat In body
• What do the ovaries do


  Produce oestrogen and eggs for pregnancy
• what does the pituitary gland do


  Produces many hormones
• what does the pancreas do

  Produces insulin and glucagon
• What do the testes do


  Produce testosterone
• What does the word hormone mean

  Chemical molecules released directly into blood
• How do hormones travel round the body

  by blood
• What is an active form


  The thing that's doing the action
• What's thyroxine and what is it secreted from


  Main hormone secreted In the bloodstream by the thyroid gland
• What is the thyroxine's active form


  Triiodothyronine
• What organs convert it to its active form

  Liver and kidney
• What do the thyroid hormones help regulate

  Metabolic rate
• what part of the brain help control the thyroxine

  Hypothamus
• What feedback loop regulates the system

  Negative loop
• Why is important that a feedback loop is put in place

  To maintains a constant level of thyroid hormones
• What is glucose needed for


  needed for the cells for respiration
• How are glucose levels monitored

  By the pancreas
• where is glucagon produced

  pancreas
• What converts stored glycogen back into glucose

  Glucagon
• What does glucagon do


  Converts stored glycogen back into glucose
• What is insulin


  Hormone produced by pancreas
• What does insulin do

  Causes glucose to be stored as glycogen in the liver and muscles