Anatomically, the endocrine system involves a collection of glands contained in various organs throughout the body. Some endocrine organs only secrete hormones. They're called primary endocrine organs. Other organs secrete hormones but this is not their main function, and they're called secondary endocrine organs. Some primary endocrine organs are located within the brain, and examples include the hypothalamus, the pituitary gland, and the pineal gland and other primary organs are located outside the brain. They include the thyroid gland, the parathyroid glands, the thymus and the adrenal glands. The pancreas and the gonads, which are the testes in males and the ovaries in females. Secondary endocrine glands include the heart, the liver, stomach, the small intestines, the kidney, and the skin. And you may come across readings that refer to hormones from any one of these secondary endocrine organs. However, our focus will be on the primary endocrine organs and hormones that have the highest implication to sports training. Specifically, these include the hypothalamus, the pituitary gland. And the adrenal gland, the pancreas, and the gonads. That is the testes and ovaries. Now, the hypothalamus and the pituitary are particularly important endocrine glands. Together, they control almost all the activity of organs throughout the body. The hypothalamus is part of the brain, so let's zero in and take a closer look at the location of the hypothalamus. Here it is here and right underneath the hypothalamus is the pituitary gland and it's connected to the hypothalamus by a little stock. The hypothalamus receives information about the state of the body. It monitors blood pressure, and body temperature, and fluids, and electrolyte balance among other things that are going on in the body and the factors that it needs to maintain homeostasis. The hypothalamus is the master controller of metabolism in the body. And you'll see how it works in a minute. Now, the adrenal glands are also important glands for athletes. They sit on top of the kidneys. And then you have the pancreas that's tucked underneath the liver. Here's the liver up here. And here's the pancreas. And the pancreas secretes two hormones that are important. One controls the amount of glucose in the blood vessel. Insulin is a critical hormone for helping glucose gain entry into the cells. And there's also glucocon that breaks down the glycogen, we'll come back and talk about them in a little bit.