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Thyroid and Parathyroid

Thyroid and Parathyroid

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This lesson will describe the functions of the thyroid and parathyroid glands as well as identify how they work together to maintain blood calcium homeostasis.

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Tutorial

What's Covered

Welcome to this lesson today on the thyroid and parathyroid glands. Today you will be learning about the structure and function of:

  1. The Thyroid
  2. The Parathyroid
  3. Thyroid Disorders

1. The Thyroid

The thyroid and parathyroid glands are located in the neck and work closely together to manage blood calcium levels. The thyroid gland secretes thyroid hormones which are abbreviated as TH. In general, thyroid hormones plays a role in metabolism, growth, and optimal functioning of the central nervous system.

The thyroid gland also secretes a hormone called calcitonin. And calcitonin is a hormone that helps to regulate blood calcium levels by lowering them if they become too high. Calcitonin signals osteoblasts in bone will to store the excess calcium within bone tissue.

Terms to Know

    • Thyroid Gland
    • The largest endocrine gland located on the anterior trachea, the thyroid gland secretes hormones that elevate basal metabolic rate (BMR) called T₃ (Triiodothyronine) and T₄. (Thyroxine) The thyroid gland also secretes a hormone called calcitonin that lowers blood calcium levels by increasing renal excretion of calcium and inhibiting osteoclasts.
    • Parathyroid Glands
    • A group of glands on the posterior thyroid that secrete parathyroid hormone to increase blood calcium levels by decreasing renal excretion of calcium and increasing osteoclast activity.

2. Parathyroid Glands

Parathyroid glands secretes parathyroid hormone, also abbreviated as PTH. Parathyroid hormone plays a role in regulating blood calcium levels. Parathyroid hormone raises blood calcium levels if they become too low by signalling osteoclasts to break down bone tissue and release calcium into the blood. Remember, this is the opposite of the hormone calcitonin that is secreted from the thyroid gland.

These two hormones actually play a role in bone remodeling and this process helps maintain homeostasis of blood calcium levels. The thyroid and the parathyroid glands play a large role in maintaining homeostasis of blood calcium levels, either by lowering blood calcium levels or raising blood calcium levels with the help of osteoblasts and osteoclasts.


3. Thyroid Disorders

  • Goiter

A simple goiter is one type of disorder that can affect the thyroid gland. In order for the production of thyroid hormone, iodine is necessary. If a person does not get enough iodine in their diet the lobes of the thyroid will enlarge and swell up. Generally in the US this is not much of a problem since you can buy iodized salts; which is where we get a good majority of our iodine.

  • Hyperthyroidism

Hyperthyroidism is a condition characterized by excess thyroid hormone in the blood which can lead to a high heart rate, elevated blood pressure, and sweating. Graves' disease is actually a disease that causes hyperthyroidism and is an autoimmune disease that stimulates overproduction of thyroid hormone.

  • Hypothyroidism

Hypothyroidism is characterized by low blood thyroid levels. If thyroid hormone levels are low, it can lead to weight gain and a person feeling sluggish. They might be intolerant to very cold temperatures.

Terms to Know

      • Simple Goiter
      • A non-cancerous enlargement of the thyroid gland that can sometimes occur on its own or when a person is lacking in iodine and the thyroid hormones.
      • Graves' Disease
      • An autoimmune disease that causes the thyroid gland to become overactive and over-secrete T₃ and T₄ and is the most common form of hyperthyroidism.

Summary

So this lesson has been an overview on the structure and function of the thyroid, parathyroid, and thyroid disorders.

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Graves Disease

    An autoimmune disease that causes the thyroid gland to become overactive and over-secrete T₃ and T₄ and is the most common form of hyperthyroidism.

  • Simple Goiter

    A non-cancerous enlargement of the thyroid gland that can sometimes occur on its own or when a person is lacking in iodine and the thyroid hormones.

  • Parathyroid Glands

    A group of glands on the posterior thyroid that secrete parathyroid hormone to increase blood calcium levels by decreasing renal excretion of calcium and increasing osteoclast activity.

  • Thyroid Gland

    The largest endocrine gland located on the anterior trachea, the thyroid gland secretes hormones that elevate basal metabolic rate (BMR) called T₃ (Triiodothyronine) and T₄. (Thyroxine) The thyroid gland also secretes a hormone called calcitonin that lowers blood calcium levels by increasing renal excretion of calcium and inhibiting osteoclasts.