The endocrine system primarily relies on the negative feedback mechanism. The endocrine system influences metabolic activities by sending out chemical messengers through the blood called hormones. Once released into the blood these hormones are transported throughout the body. The effects of these hormones are wide spread and vary from reproduction, growth and development, immunities, maintaining electrolyte levels, water and nutrient balance, and metabolism. Metabolism involves catabolism, which is a process where complex molecules are broken into simple substances, and anabolism which is the process when simple substances are made into complex molecules by the use of enzymes. During the catabolism process the energy is released and is used to make ATP. The most important hormone in maintaining metabolism is thyroxine which is produced by the thyroid gland. The production of thyroxine is really controlled by the pituitary gland which secretes Thyroid Stimulating Hormone (TSH). When (TSH) is released into the bloodstream to the thyroid gland, the thyroid gland produces more thyroxine. Rising thyroid hormone levels send a negative feedback response to the hypothalamus, which results in it producing Thyrotropin Releasing Hormone (TRH) which regulates the release of (TSH). Thus, the hypothalamus and the pituitary gland control the release of thyroxine (TSH), and (TRH), which in turn controls the metabolic rate. In this experiment we have seen how different glands and their secretions, while being independent of each other maintains the metabolism. Objectives:
Activity 1: Determining the Baseline Metabolic Rate.
Activity 2: Determining the effects of Thyroxine on the metabolic rate.
Activity 3: Determining the effects of TSH on the metabolic rate.
Activity 4: Determining the effects of Propylthiouracil on the metabolic Rate.