paper 2

• homeostasis 


  the regulation of conditions inside your body to maintain a stable internal environment in response to changes in both internal and external conditions
• receptor 


  detects a stimulus
• co ordination centre 


  receives and processes the information then organises a response
• effectors 


  produce a response which counteracts the change and restores the optimum level
• stimulus 


  a change in the environment
• central nervous system (CNS)


  consists of the brain and spinal chord it’s connected to the sensory neurones and motor neurones
• sensory neurones 


  the neurones that carry information as electrical impulses from the receptors to the cns
• motor neurones 


  the neurones that carry electrical impulses from the cans to the effectors
• effectors 


  all your muscles and glands which respond to nervous impulses
• synapses 


  gap between two neurones
• example of reflex arc 


  1.bee stings finger

  2.stimulation of pain receptors

  3.impulses travel along a sensory neurone

  4.impulses are passed along a relay neurone via a synapse

  5.impulses travel along a motor neurone via a synapse

  6.when impulses reach muscle it contracts
• hormones 


  are chemical molecules released directly into the blood
• pituitary gland


  produces many hormones that regulate body conditions,sometimes called the master gland because these hormones act on other glands directing them to release hormones which bring about change
• ovaries 


  produce oestrogen which is involved in the menstrual cycle
• testes 


  produce testosterone which controls puberty and sperm production
• thyroid 


  produces thyroxine which is involved in regulating things like the rate of metabolism,heart rate and temperature
• adrenal gland 


  this produces adrenaline which is used to prepare the body for a fight or flight response
• pancreas 


  this produces insulin which is used to regulate the blood glucose level
• insulin and glucagon 


  control blood glucose level
• diabetes 


  condition which effects your ability to control your blood sugar levels
• type 1 diabetes 


  where the pancreas produces little or no insulin

  people with type one need insulin therapy
• type 2 diabetes

  where a person becomes resistant to their own insulin

  type two diabetes can be controlled by eating a carbohydrate controlled diet and exercise
• 4 stages of the menstrual cycle

  1.menstruation starts,the uterus lining breaks down for about 4 days

  2.the uterus lining builds up again

  3.an egg develops and is released from the ovary

  4.the wall is then maintained
• FSH (follicle stimulating hormone)


  -produced in the pituitary gland

  -causes an egg to mature in one of the ovaries in a structure called the follicle

  -stimulates the ovaries to produce oestrogen
• oestrogen 


  -produced in the ovaries

  -causes lining of the uterus to grow

  -stimulates the release of the LH
• LH (luteinising hormone)


  -produced by the pituitary gland

  -stimulates the release of an egg
• progesterone 


  -produced in the ovaries by the remains of the follicle after ovulation

  -maintains the lining of the uterus during the second half of the cycle

  -inhibits the release of LH or FSH