Anatomy and Physiology / Unit 7: The Endocrine System
7.3 Thyroid, Parathyroid and Adrenal Glands
Notes
- Thyroid gland: makes thyroid hormones (T3 and T4, require iodine) that set the metabolic rate, and calcitonin (lowers blood calcium). Hyperthyroidism (Graves' disease): fast metabolism, weight loss, heat intolerance, rapid heart rate. Hypothyroidism: slow metabolism, weight gain, fatigue, cold intolerance. Iodine deficiency can cause a goiter (enlarged thyroid).
- Parathyroid glands (four, on the thyroid): PTH raises blood calcium.
- Adrenal glands sit on the kidneys. Adrenal cortex: aldosterone (retains sodium and water, raises blood pressure), cortisol (long-term stress response, raises blood glucose, suppresses inflammation), and sex hormones. Adrenal medulla: epinephrine and norepinephrine (short-term "fight or flight": faster heart rate, higher blood glucose, bronchodilation).
- Addison's disease: low cortisol and aldosterone. Cushing's syndrome: excess cortisol.
Practice
A patient has weight loss, a fast heartbeat, sweating and heat intolerance. Which disorder is most likely?
Excess thyroid hormone speeds metabolism.
A person who lives far from the sea and eats little iodine develops an enlarged thyroid. This is called a:
Without iodine, thyroid hormone is low; high TSH causes the thyroid to enlarge.
A sudden fright causes a racing heart and wide airways. Which hormone is mainly responsible?
The adrenal medulla releases epinephrine in the short-term stress response.
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