Thyroid Gland Functions & Secretions: Vocabulary

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Terminology Related to Underactive Thyroid Disorders

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:00 Thyroid
  • 0:50 T3 and T4
  • 2:30 Calcitonin
  • 3:35 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed
Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

The thyroid gland is a very important component to a number of body processes. In this lesson, we'll discuss the functions of the thyroid gland as well as the hormones it secretes.


Do you know someone who's always hot or always cold? If so, their body's furnace, a.k.a. their thyroid gland, might be a bit off. Your thyroid gland, which is sometimes referred to simply as your thyroid, is a butterfly-shaped gland found at the base of your neck. If you could see it through your skin, it would almost look like you're wearing a natural bow tie.

The thyroid produces three hormones; two of those hormones help regulate your metabolism, which is basically how fast your body burns up energy. If you're thyroid furnace is pumping out too many hormones, your metabolism heats up. If you're thyroid furnace is set too low, you feel the chill of the low energy burn.

Let's take a closer look at the hormones that come from the thyroid gland.

T3 and T4

I mentioned that the thyroid gland is shaped like a butterfly. The butterfly wings are the lobes of the gland. Inside the lobes, we find sac-like follicles filled with colloid, which is a semi-fluid material. The two hormones that influence your metabolism are derived from this colloid. These hormones are called triiodothyronine (or T3) and thyroxine (or T4).

In your body, we see that T3 and T4 work together to control things like metabolism, body temperature, growth and development, and heart rate. The hormones are not only similar in their function but also in their chemical makeup. The hormones are made up of tyrosine amino acids combined with iodine atoms. If you look at the full name for T3, you see the term 'iodo' hidden inside. I use this hidden term to remind myself that the thyroid hormones are constructed of iodine atoms.

This is an important fact to keep in mind because it means that you need to take in dietary iodine in order for your body to function properly. For people living in the United States, this isn't a difficult task. We can go to the grocery store and buy something called iodized salt, which is simply table salt with iodine added to it. Access to this easy iodine source might not be as readily available in all countries, but iodine can be obtained from other foods, such as some dairy products and seafood.


When it comes to learning about the thyroid gland, T3 and T4 kind of steal the show, but there's another hormone secreted from your thyroid that plays an important role in depositing calcium into the bones. This hormone is referred to as calcitonin. I remember the function of this hormone by thinking of 'calci-ton-in' as the hormone that tones up your bones by putting calcium in.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account