How tall can a person become?
This may be an exaggeration, but the world's tallest person, Robert Pershing Wadlow, stood almost nine feet tall when he died at the age of 22. Is growing that tall due to a problem with the endocrine system?
Endocrine System Disorders
Diseases of the endocrine system are relatively common. An endocrine disease usually involves the secretion of too much or not enough hormone. When too much hormone is secreted, it is called hypersecretion. When not enough hormone is secreted, it is called hyposecretion.
Hypersecretion by an endocrine gland is often caused by a tumor. For example, a tumor of the pituitary gland can cause hypersecretion of growth hormone. If this occurs in childhood, it results in very long arms and legs and abnormally tall stature by adulthood. The condition is commonly known as gigantism (see Figure below). See Giants - Part 1 - Pituitary Gigantism and Acromegaly at http://www.youtube.com/watch?v=Ebhf1qKVA9A&feature=youtu.be for information about pituitary giants.
Hypersecretion of growth hormone leads to abnormal growth, often called gigantism.
Destruction of hormone-secreting cells of a gland may result in not enough of a hormone being secreted. This occurs in type 1 diabetes. In this case, the body’s own immune system attacks and destroys cells of the pancreas that secrete insulin. A person with type 1 diabetes must frequently monitor the level of glucose in the blood (see Figure below). If the level of blood glucose is too high, insulin is injected to bring it under control. If it is too low, a small amount of sugar is consumed.
To measure the level of glucose in the blood, a drop of blood is placed on a test strip, which is read by a meter.
In some cases, an endocrine gland secretes a normal amount of hormone, but target cells do not respond to the hormone. Often, this is because target cells have become resistant to the hormone. Type 2 diabetes is an example of this type of endocrine disorder. In type 2 diabetes, body cells do not respond to normal amounts of insulin. As a result, cells do not take up glucose and the amount of glucose in the blood becomes too high. This type of diabetes cannot be treated by insulin injections. Instead, it is usually treated with medication and diet.
- Endocrine system disorders usually involve the secretion of too much or not enough hormone. For example, a tumor of the adrenal gland may lead to excessive secretion of growth hormone, which causes gigantism.
- In Type 1 diabetes, the pancreas does not secrete enough insulin, which causes high levels of glucose in the blood.
Use this resource to answer the questions that follow.
- Describe the following endocrine disorders:
- growth disorders
- Polycystic Ovary Syndrome
1. Define hypersecretion. Give an example of an endocrine disorder that involves hypersecretion.
2. Tasha had a thyroid test. Her doctor gave her an injection of TSH and 15 minutes later measured the level of thyroid hormone in her blood. What is TSH? Why do you think Tasha’s doctor gave her an injection of TSH? How would this affect the level of thyroid hormone in her blood if her thyroid is normal?
3. After the thyroid test, Tasha’s doctor said she has an underactive thyroid. What symptoms would you expect Tasha to have? Why?
4. Explain why a person with type 2 diabetes cannot be helped by insulin injections.