#endocrine #glands #organs #hormones #thymus #thyroid #brain #hypothyrodism #types of hormones #function of hormones #purpose of endocrine system #human body systems #signaling #chemical signaling #science #biology #TEKS #amoeba sisters #ameba sisters #amoba sisters #ameeba sisters #overview #review #basics #introduction #tutorial #animation #cartoon #educational #AP biology #school #standards #endocrine vs exocrine #exocrine