Module 2 The Endocrine System

Big Picture

Stressed! Stressed out! and ready to explode—we deal with stress everyday. You might deal with it by eating a bag of cookies, or you might find that your body just needs sleep to recover. Your body needs to adjust to external and internal stresses or changes so that they do not become a detriment to your health. Staying healthy means appropriate choices in how you identify and cope with stress.

Consider the case study of Emily, a thirty year old woman who today lives with the constant stress of an endocrine disorder. Her career goals and life plans are continually interrupted by her health issues.

When she was in Grade 12, Emily developed extreme fatigue and complained that her whole body ached. Even her bones hurt! She felt weak and began finding it very difficult to keep up with the readings and the homework that her teachers assigned. She also noted that she couldn’t focus the microscope in the lab, and that at times, her vision was blurred. It was at this point that her parents took her to see a series of physicians and medical specialists. After extensive tests and consultations, Emily’s doctors confirmed that she had a rare inherited endocrine disorder called familial multiple endocrine neoplasia type 1 (FMEN1). In Unit C, you will learn how Emily inherited this disorder, and you will come to understand how this disorder has impacted Emily’s daily life as well as her longevity.

In FMEN1 specific endocrine glands, such as the parathyroid glands, pituitary gland, pancreas, adrenal glands, or a combination of them become overactive due to the growth of mostly benign, or non-cancerous, tumors called neoplasms. These tumors disrupt normal function by crowding nearby structures and cells. For example, a tumor in the pituitary gland can press against surrounding pituitary tissue, thereby damaging the normal part of the tiny pituitary gland, or the nerves that carry visual information from the eyes. In the picture, notice the very close alignment of the pituitary gland and the optic nerve. This is one reason why Emily’s vision was blurred.

In this module you will explore the big question of how the body uses chemical messengers to respond to stimuli, including stress, to establish homeostasis.

Throughout the module you will explore the following focusing questions:

How is the endocrine system organized, and how do its parts communicate with each other and other parts of the body?
Who is the “boss” of the endocrine system, and how is control of the endocrine system managed?
How do the major endocrine glands, including the anterior and posterior pituitary gland, the thyroid gland, the parathyroid glands, the pancreas, and the adrenal glands contribute to homeostasis?
What are the metabolic roles fulfilled by hormones in the maintenance of homeostasis, and,what are the physiological consequences of hormonal imbalances?
How do the nervous and the endocrine systems interact to maintain overall homeostasis?