negative feedback

• what is thyroxine?


  A hormone produced in the thyroid gland that plays a vital role in regulating the bodys metabolic rate
• define metabolic rate


  The speed at which the body transfers energy from its chemical stores in order to perform its functions
• what is the function of the thyroid gland?

  To take iodine and convert it into thyroxine by combining it wirh the amino acid tyrosine
• where is iodine found?

  In many foods
• what is adrenaline also known as?

  The fight or flight response
• what is negative feedback?

  An important type of control that is used in homeostasis
• what is the cycle of negative feedback?

  conditions in the body change from set point , change detected by a receptor, corrective mechanisms activated by an effector, conditions returned to set point, corrective mechanism switched off
• what are examples of things that need to stay at constant levels?

  Blood glucose concentration and temperature
• what is the negative feedback cycle for thyroxine?

  Hypothalamus detects cells need more energy, pituitary releases thyroid stimulating hormone (TSH), thyroid produces thyroxine, hypothalamus detects that cells have enough energy, pituitary stops producing TSH, thyroid stops producing thyroxine
• what does thyroxine control?

  How much energy is available to cells
• what does more thyroxine mean?

  The metabolic rate is increased, allowing cells to transfer additional energy
• state the location of the centre that controls thyroxine levels?

  Hypothalamus and pituitary gland
• how does adrenaline make the body respond?

  1, faster breathing to increase the rate of ATP production and cope with demand for oxygen

  2, increased heart rate

  3, diverting blood away from areas such as the digestive system and towards the muscles
• what happens after the stress is removed?

  The affected body systems return to their previous state