Hormones are frequently talked about, and you may hear things like “my hormones are out of balance” or “I have hormonal acne.” Hormones play a large role in making sure the body works properly across tons of your normal body processes, and affects almost all systems including the musculoskeletal, respiratory, cardiovascular, renal, and reproductive systems. It is amazing how something so small that cannot be seen with the naked eye can have such a large network of pathways throughout the body.
So, you may be wondering — how exactly do hormones work? Well, keep reading to learn more about what hormones are, where they are made, the different types, and how they work in the body.
What Are Hormones?
Hormones are small chemical messengers that help to make up the endocrine system. These hormones are made in the glands located around the body and then spread in the blood. The hormones are chemicals with different structures and each different structure carries out a different function in the body.
Some hormones are made up of a structure similar to a fat cell, called fat-soluble hormones. While others are made up of water-like molecules and are called water-soluble hormones. Each unique hormone binds to unique receptor proteins of different cells to signal a specific response, which is why it can play so many different roles in the body — because there are so many different types of hormones.
Where Are Hormones Made?
You know that hormones are made in glands, which are the other half of the endocrine system. Glands are organs that release substances like hormones. There are both endocrine and exocrine glands. Exocrine glands are those that secrete a substance like saliva or sweat onto a surface, whereas endocrine glands release hormones into the bloodstream. Some glands can also function as both endocrine and exocrine.
For example, the pancreas acts as an endocrine gland by secreting insulin, somatostatin, and more, while also being exocrine by secreting digestive enzymes to help break down your food.
The glands are located throughout the entire body. In the brain, there are the hypothalamus, pituitary gland, and pineal gland. In the neck and chest, there are the thyroid gland, parathyroid glands, and thymus. In the abdomen, there is the stomach, liver, pancreas, kidneys, and adrenal glands. In the pelvic region, there is the ovary, placenta (when pregnant), and uterus for females, and testes in males.
All of these glands in these different tissue types release and produce different hormones that travel to various parts of the body to mediate changes and cellular responses that can be wildly different from one another.
All of these glands are important, but the pituitary gland is often called the master gland because it releases the most hormones out of all of the glands and they tell other glands in the body to produce their hormones.
Types of Hormones
Hormones can be broken down into many different categories, including endocrine or exocrine, lipid or water-soluble, and more. If a hormone is lipid or water-soluble it is important to understand how the hormone works in the body.
Water Soluble Hormones
Water-soluble hormones are those that are easily dissolved in water. The structure is similar to that of water so it can easily travel through the blood. The water-soluble hormone is also referred to as hydrophilic, meaning water-loving.
Water-soluble hormones do not mix well with fat molecules. This is similar to the way water and oil do not mix well in a salad dressing or in a bottle.
Understanding this mechanism is integral to understanding how the hormones work in the body. Luteinizing hormone, insulin, and thyroid-stimulating hormone are all examples of water-soluble hormones.
How Water Soluble Hormones Work
Blood is made of mostly water, which is why water-soluble hormones are easily dissolved and can travel through the blood. After water-soluble hormones are released from the gland, the hormone travels freely through the blood and to the target organ or cell.
When it arrives at its target cell the hormone attaches to a protein receptor on the outside of a cell. This outside of the cell is called the plasma membrane and is made up of two layers of phospholipids which are made of fat cells. Since the water and fats do not mix, the water-soluble hormone cannot cross cell membranes and so instead signals to the cell surface receptors. Once the receptor is signaled on the surface of a cell, a cascade of events happens inside the cell, called a signaling pathway, and the appropriate action occurs.
Examples of Water Soluble Hormones
Many water-soluble hormones are created in the body, but luteinizing hormone and growth hormone are two examples.
Luteinizing hormone is produced in the pituitary gland and is received in the testes and ovaries. When luteinizing hormone (LH) is released in women, estrogen is triggered to be released in the ovaries. When the luteinizing hormone is released in men, testosterone is released from the testes. Without adequate levels of luteinizing hormone, the body would not make adequate sex hormones and could result in a multitude of problems.
Growth hormone is a water-soluble hormone that is released by the pituitary gland. Growth hormone is present in both children and adults. Growth hormone is important in ensuring children grow at an appropriate rate. In adults, growth hormone still plays an important job in ensuring the body is maintained. It promotes adequate strength of bones and muscles, reduces the amount of body fat, and helps to improve exercise stamina. When people have low levels of growth hormone they may have growth disorders or simply notice a decline in muscle mass and an increase in overall body fat.
Lipid Soluble Hormones
Lipid soluble hormones are hormones that are similar to a fat or lipid molecule. These hormones are often referred to as hydrophobic, water-hating, or lipophilic, fat-loving.
Many of the lipid-soluble hormones are considered steroid hormones such as testosterone, estrogen, and progesterone. Steroid hormones are hormones with a 4 carbon ring structure with a tail that has a unique structure that differentiates between the various steroid hormones. These steroid hormones all begin from the structure of cholesterol and then are differentiated into the hormones. Overall, lipid hormones are easily dissolved in fat molecules and cannot be easily dissolved in the blood, like water-soluble molecules.
How Lipid Soluble Hormones Work
Lipid soluble hormones can not travel in the blood as easily, and instead, travel attached to a carrier protein in the blood and carries it to its destination. The protein acts as a sort of shuttle to carry the lipid hormone to the target tissue, organ, and cell. Once the hormone reaches the cell, it can pass through the plasma membrane of the cell and reach the inside where the necessary receptors wait.
Once the receptor is reached, there is a set of chemical reactions that take place to set off the appropriate response. Lipid soluble hormones may not be able to travel alone through the blood, but with the help of a transport protein, they can create very important functions in the body.
Examples of Lipid Soluble Hormones
Several lipid hormones exist, but testosterone and estrogen are two of the most commonly recognized.
Testosterone is a primarily male hormone but is produced in much lower amounts in females. Testosterone is made in the testes in males and in the adrenal glands in females. Testosterone in males is very important for the reproductive system, but it also has a very important role in the rest of the body. In the reproductive system, it is important for producing sperm and maintaining libido. For example, testosterone is important for muscle growth, bone mass, making red blood cells, and mental health. When levels of testosterone are not in balance there can be systemic effects that negatively impact the quality of life.
Estrogen is another lipid-soluble and steroid hormone that is similar in structure to testosterone. Estrogen is primarily in females and is made in the ovaries, but it is also in trace amounts in men as well. In females, estrogen is responsible for bone health, heart health, sex drive, skin, and temperature regulation in the body. Estrogen also comes in 3 different forms including estradiol, estriol, and estrone. Each of these has a certain stage of life that they are most important in. Estradiol is mostly in women of childbearing age. Estriol is in high amounts during pregnancy. Estrone is the estrogen that is present after menopause.
Overall, hormones work by being released from the appropriate gland and then traveling through the blood to reach their target organ or cells. Depending on the form of the hormone will impact the way it can travel through the blood, but the end result is the same. Ensuring that the hormones are in the correct balance is important and if they are not it likely needs to be addressed by your healthcare provider.