Thyroxine - Higher
Hormone produced by the thyroid to control metabolism. is produced from the Gland located at the base of the neck which controls metabolic rate by releasing the hormone thyroxine., which stimulates the metabolic rate. It controls the speed at which oxygen and food products react to release energy for the body to use. Thyroxine also plays an important role in growth and development. Its levels are controlled by A mechanism where changes to conditions cause an action to reverse the change, to keep conditions stable..
The Part of the brain which controls water balance, temperature and secretion of hormones by the pituitary gland. and An endocrine gland that is located just below the centre of the brain. It releases a number of important hormones. have important roles in detecting and controlling thyroxine levels.
- Low thyroxine levels in the bloodstream stimulate the hypothalamus to releaseThyrotropin releasing hormone produced by the hypothalamus in response to a lack of thyroxine in the blood. and this causes the pituitary to releaseThyroid stimulating hormone produced by the pituitary gland in response to TRH. so the thyroid releases more thyroxine. So blood levels return to normal.
- Normal thyroxine levels in the bloodstream inhibit TRH release from the hypothalamus and the production of TSH by the pituitary, so normal blood levels are maintained.
The control of thyroxine levels by the hypothalamus and pituitary gland is an example of negative feedback.