Billy's remarkable voiceIntroductionBilly is an elderly man who has experienced "remarkable" vocal changes throughout his life. Long-term growth and development result from hormone secretion in the endocrine system. As an individual ages, hormone secretion changes, thereby altering the structure and function of the human body. As a young boy, Billy was a falsetto singer in a choir until he underwent the hormonal changes associated with puberty. He developed a broken tenor that was difficult to control as well as his temper. During this time, I also built more muscle mass after starting bodybuilding. After participating in choir, he got into rock and roll and country western singing. As it stands, his voice is crackly and monotonous. This report will attempt to study the hormonal mechanisms underlying the growth and development of Billy's body throughout his life, particularly the mechanisms of the endocrine system. Organs of the Endocrine System (Classes.midlandstech.edu, 2014) Figure 1: The diagram above shows the location of the endocrine organs. The organs of the endocrine system include the hypothalamus, thymus, pancreas, parathyroid glands, ovaries, testes, pituitary gland, adrenal glands, pineal gland, and thyroid gland. These endocrine organs are responsible for regulating reproduction, growth, metabolic rate and energy, water and nutrient balance, cardiac output, blood pressure and reproduction (Porterfield, 2001; Finlayson & Sanders, 2007; Hormone secretionHormones in the endocrine system allow cells to communicate to maintain homeostasis in the body, a process that continually aims to create a ball...... middle of paper ......: Singular Pub. GroupSchneider, B., Cohen, E., Stani, J., Kolbus, A., Rudas, M., Horvat, R. and van Trotsenburg, M. (2007). Towards the expression of sex hormone receptors in the human vocal cord. Journal of Voice, 21(4), pp.502-507.Steroidal.com,. (2013). Testosterone. Accessed May 18, 2014 from http://www.steroidal.com/testosterone/Tokresource.org. (2014). nerves, hormones and homeostasis. Retrieved May 18, 2014 from http://www.tokresource.org/tok_classes/biobiobio/biomenu/nerves_hormones_homeostasis/index.htm Tortora, G. and Grabowski, S. (2001). Introduction to the human body (1st ed.). New York: Wiley.Uninursety.com. (2014). UniNursety – Study anywhere, anytime!. Retrieved May 18, 2014 from http://www.uninursety.com/user/courses_n/bloodgas_patientcare.phpZemlin, W. (1998). Speech and hearing science (4th ed.). Boston: Allyn and Bacon.