Endocrine System Part III

Thyroid

The thyroid (pronounced: THY-royd), located in the front part of the lower neck, is shaped like a bow tie or butterfly and produces the thyroid hormones thyroxine (pronounced: thy-RAHK-sin) andtriiodothyronine (pronounced: try-eye-oh-doe-THY-ruh-neen). These hormones control the rate at which cells burn fuels from food to produce energy.

The production and release of thyroid hormones is controlled bythyrotropin (pronounced: thy-ruh-TRO-pin), which is secreted by the pituitary gland. The more thyroid hormone there is in a person's bloodstream, the faster chemical reactions occur in the body.

Why are thyroid hormones so important? There are several reasons — for example, they help kids' and teens' bones grow and develop, and they also play a role in the development of the brain and nervous system in kids.

Parathyroids

Attached to the thyroid are four tiny glands that function together called the parathyroids (pronounced: par-uh-THY-roydz). They release parathyroid hormone, which regulates the level of calcium in the blood with the help of calcitonin (pronounced: kal-suh-TOE-nin), which is produced in the thyroid.

Adrenal Glands

The body also has two triangular adrenal (pronounced: uh-DREE-nul) glands, one on top of each kidney.

The adrenal glands have two parts, each of which produces a set of hormones and has a different function:

1. The outer part, the adrenal cortex, produces hormones calledcorticosteroids (pronounced: kor-tih-ko-STER-oydz) that influence or regulate salt and water balance in the body, the body's response to stress, metabolism, the immune system, and sexual development and function.
2. The inner part, the adrenal medulla (pronounced: muh-DUH-luh), produces catecholamines (pronounced: kah-tuh-KO-luh-meenz), such as epinephrine (pronounced: eh-puh-NEH-frun). Also called adrenaline, epinephrine increases blood pressure and heart rate when the body experiences stress.