homeostasis and response

• homeostasis definition

  maintenance of a constant internal environment in the body
• what does homeostasis include

  control of blood glucose conc, body temp and water and ion levels
• receptors 


  detect change in environment
• effectors


  carry out response that restore optimum levels
• what's the CNS


  brain and spinal cord
• stimuli


  change in environment
• motor neurone


  directly control muscle movement. transmits impulses from spinal cord to skeletal and smooth muscles
• sensory neurone


  transmits electrical impulse from receptor to CNS. activated by sensory input from environment
• how do impulses cross synapse


  neurotransmitter diffuses across synapse and transmit electrical impulse. nerve impulses then are transmitted along next nerve cell
• glucose


  sugar used in respiration
• glycogen


  storage carbohydrate found in liver and muscles
• glucagon


  hormone that stimulates the liver to break down glycogen to glucose
• rise in blood glucose 


  beta cells in pancreas detect and secrete insulin. this causes uptake of glucose by body cells and conversion of glucose to oxygen and fat. results in a decrease of glucose levels in bloodstream
• fall in blood glucose


  alpha cells in pancreas detect and secrete glucagon. causes conversion of glycogen to glucose in muscles and liver.
• what is negative feedback?


  a response that happens in the body which is opposite to the initial change
• reflex process


  pain is detected by receptor

  receptor send impulse to CNS

  impulse passes through relay neurone

  motor neurone carries impulse to effector

  effector responds
• what's the endocrine system made up of

  glands that secrete hormones directly into the bloodstream,
• pituitary gland 


  master gland - secretes several hormones in response to body conditions
• what causes type 1 diabetes

  pancreas not producing enough insulin
• what causes type 2 diabetes


  body cells losing ability to respond to insulin
• FSH


  causes eggs to mature in the ovaries

  stimulates ovaries to produce oestrogen
• where is FSH secreted from

  pituitary gland
• oestrogen 


  inhibits FSH release

  stimulates LH release

  makes lining of uterus grow again after menstruation
• LH


  stimulates release of egg from ovaries
• where's oestrogen secreted 


  ovaries
• progesterone 


  maintains lining of uterus

  inhibits LH and FSH release
• process of IVF


  give women more FSH and LH to stimulate growth of egg

  take egg

  fertilise eggs with fathers sperm in a laboratory

  insert embryo in woman