hormones and nerves

• what is a hormone?

  a hormone is a chemical substance produced by a gland and is carried in the bloodstream which alters the activity of specific target organs
• master gland

  the pituitary gland in the brain is known as the master gland. it secrets several hormones into the blood in response to the bodys conditions such as blood water levels. these hormones can also act on other glands to simulate the release of different hormones and bring about effects
• adrenalin 


  adrenalin comes from the adrenal glands and prepares for fight or flight. it has several targets including the respiratory and circulatory system. the effects include; increased breathing and heart rate, increased flow of blood to muscles and increased conversion of glycogen to glucose
• what is negative feedback?

  negative feedback is the action taken by the body to return something to its normal/optimum level.
• thyroxine 


  thyroxine is produced from the thyroid gland. it controls the speed at which oxygen and food products reacts to release body for the energy to use. thyroxine plays an important role in growth and development. thyroxine levels are controlled by negative feedback
• insulin: a hormone produced in the pancreas that lowers blood glucose levels
• type one diabetes: pancreas produces little or no insulin. this can be detected from an early age. it can be controlled by injecting insulin. people have to monitor their blood sugar levels and control their diet.
• type two diabetes: the persons body cells no longer responds to insulin being produced. it can be controlled by a carbohydrate diet and exercise. carbohydrates are broken down into glucose and blood glucose levels are raised.