Overview
The endocrine system is a human body system made up of several different types of hormones, a group of glands that secrete these different hormones straight to the blood stream to then be carried into other distant organs in the body systems. In humans, the major endocrine system glands include the pineal gland, the pituitary gland, ovaries (in women), thyroid, testes (in men), the pancreas, and the adrenal glands. In some of the vertebrae, the hypothalamus gland is the only source of authority for the entire endocrine system. The field of study dealing with the endocrine system, endocrinology, and its many different diseases is studied by endocrinologist. Besides the main endocrine glands, many other organs that are part of other body systems have another function in the endocrine system, such as bones (this role was , kidney, liver, heart and gonads. It was recently discovered that even the skeleton has a role in the endocrine system. One explained example of this is the kidneys. The kidney, besides doing it’s excretory system ‘job’, secretes hormones to other places in the body. Hormones can consist of either amino acid complexes, steroids, and many other components. The endocrine system can be considered the opposite of the excretory system, which secretes its hormones to the outside of the human body. On the other hand, the endocrine system’s hormones travel huge distances inside the body.
The Hypothalamus Gland
The hypothalamus gland, stemming from the Greek roots hypo-under, and thalamus, a part of the brain, is a gland in the endocrine system. The Hypothalamus contains very small nuclei that have an wide variety of functions. One of the most important functions of the hypothalamus is to connect the nervous system to the endocrine system via the pituitary gland, another gland in the endocrine system. The hypothalamus is found in front of the pharynx, and is considered a part of the limbic system. The limbic system is a group of the brain that contributes to emotion, behavior, and long term memory. Most all the vertebrae in the spine contain some link to the hypothalamus. In humans, the hypothalamus gland is close to the size of an almond, and weighs just under one gram. The hypothalamus regulates certain processes involving our metabolism, and other assorted activity with the autonomic nervous system. The gland secretes certain hormones interacting with the nervous system, called releasing hormones or hypothalamic hormones. In turn, releasing hormones limit the secretion of hormones from the pituitary gland. The hypothalamus controls many things. A few examples are body temperature, hunger, important attachment behaviors, fatigue, and sleep.
The Pituitary Gland
The pituitary gland, also called the hypophysis, is an endocrine gland about the size of a pea in humans. It is a extension off the bottom of the hypothalamus at the base of the brain. The pituitary gland rests in the center of the middle back half of the brain, and is surrounded by a small bony cavity. There are three parts to the pituitary; anterior, intermediate, and posterior. The anterior pituitary is a part of the gland that controls several processes, such as stress, growth, reproduction. The posterior pituitary is a piece of the gland that is connected to the hypothalamus by a small tube called the pituitary stalk. Hormones sent out from the pituitary gland help control things like growth, blood pressure, and functions of sex organs. It also controls some aspects of pregnancy, childbirth, temperature regulation and pain relief.
Adrenal Gland
The adrenal glands (also known as suprarenal glands because they are located on top of the kidneys) are endocrine glands that produce a variety of hormones including adrenaline and cortisol. Adrenaline is a hormone that speeds up the beating of the heart. It also fuels the fight or flight response. Cortisol kicks in after the fight or flight response. It does the opposite; it calms down the body by lowering the rate glucose is burned. It also slows down the heart. Each adrenal gland has multiple parts: the outer cortex and the inner medulla. A great number of endocrine diseases involve something of the adrenal gland not functioning right. One example of this is Cushing’s syndrome. Overproduction of cortisol, the calming hormone, leads to Cushing's syndrome. On the contrary, insufficient production of adrenal hormones is associated with Addison's disease. Addison’s disease causes the teeth to turn red, almost looking blood stained. There is a great variety of tumors that can form from adrenal tissue, and they are often found when medical imaging is done while attempting to diagnose other diseases.
Pineal Gland
The pineal gland is a small gland that is located in the brain connected to the vertebrae in the spine. The pineal gland produces the hormone melatonin which controls our sleeping pattern. The shape of the pineal gland can remind you of a pine cone. Thus its name, pineal gland. The pineal gland can be found inside of the epithalamus, near the middle of the brain. As a result of many scientific projects researching evolutionary biology, scientists have been able to explain the increasing diversity of the pineal gland in several dissimilar vertebrate species. According to biological evolution, the pineal gland is a kind of atrophied photoreceptor, meaning that it can pick up light. In the middle of the brain for some species of amphibians and reptiles, it is linked to a organ that detects light, known as the third eye. This can be observed today, possibly in our backyards. Some reptiles and amphibians can be seen with some sort of dot pattern in between their eyes, or on the back of their head.
Thyroid
The thyroid gland is a gland in the endocrine system in the neck, consisting of two lobes. It is found at the front of the neck, right below the Adam's apple. The thyroid gland secretes different, special thyroid hormones, which majorly control the metabolic rate and protein synthesis. Protein synthesis is the process of the central dogma, or the reproduction of cells. The hormones also have many other effects such as those on bodily development. The thyroid is able to be infected and not function right when invaded by several different disease. There are also some diseases that are there because of other diseases. Most thyroid diseases have some weird side effects. Two examples of these gateway diseases are hyperthyroidism and hypothyroidism. Hyperthyroidism happens when the thyroid makes way too many thyroid hormones. This mostly happens because of something called Graves' disease. Graves’ disease is an autoimmune disease. Autoimmune means that the disease hides its self among healthy cells. So the body has to attack its self in order to get rid of the disease. In contrast, hypothyroidism is a disease that occurs because there is a great lack of thyroid hormones. In addition to all of this, the gland can possibly get a few types of cancer. The thyroid can produce the unique hormone calcitonin. Calcitonin plays a role in calcium homeostasis. Homeostasis is essentially the state of being in the body functioning normal. It’s commonly said that homeostasis is life. When homeostasis is threatened, that means that your life is in danger, medically speaking.
Thymus
The thymus gland is a gland in the endocrine system, and also has functions in the immune system, such as producing T-Cells. The thymus gland will not be functioning throughout your whole lifetime, but it has a big responsibility when it’s active—helping the body protect itself against autoimmunity. The thymus has a super big role in the lymphatic system (your body’s defense network made up of T-Cells, B-Cells, etc.).
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