Endocrine System: What Is It?
There are a number of organs and glands that help to control the production, storage and secretion of hormones around the body. This is known as the endocrine system.
The main glands within this system include the thyroid, hypothalamus, adrenal, ovary, testes, pineal, pituitary and parathyroid glands. Among the organs, the pancreas is also cassed a gland when considered as part of this system. Another organ includes the thymus. Other organs that help with the secretion of the hormones, but are not actually part of the endocrine system, are the heart, liver, kidneys, lungs, brain, placenta and skin.
Endocrine means to responed to certain stimuli and produce hormones and then release them into the body’s bloodstream.
The Function of the Endocrine System
The endocrine glands produce the hormonal compounds that areneeded for development, growth and the metabolism. They are also responsible for the composition of the electrolytes in the fluids and for reproduction. The pancreas and separate glands are all required for specific and unique needs.
The Pituitary Glang
This is the main one of the whole system and is found at the bottom of the brain. It is relatively small – just the size of a regular marble – and is in two separate parts: the posterior and anterior. The anterior is required for stimulating the other glands in the system, including the testis, ovary, thyroid and adrenal glands so that they produce the hormones required and affect the specific organs they are supposed to.
Three hormones from this gland act on others: the gonadotropins, adrenocorticotropic hormone (ACTH) and the thyroid-stimulating hormone (TSH). The gonadotropins regulate the female and male sex hormone production, along with the sperm and egg cells. The ACTH is reponsible for stimulating the adrenal cortex for the production of corticosteroid hormones, along with some of the female and male sex hormones. The THS stimulates the production and release of the thyroid hormone from the thyroid gland.
The growth hormone (GH) is another important hormone in the pituitary gland. This controls the development and growth of various parts of the body, such as the muscle, organs and tissue. It is also linked to the metabolism and the way the protein, fat and carbohydrates are used by the body. The GH reduces the use of glucose in the adipose tissue and muscle cells and increase the levels within the blood. This promotes certain liver molecules to produce glucose. GH is also responsible for increasing the number of amino acids taken by cells to help stimulate the breakdown of fat in the adipose tissue. Prolactin is also created in femals to help with regulating the production of breast milk and develop the breasts.
Oxytocin and vasopressin are two hormones that the posterior pituitary stores, although it does not produce them. Oxytocin helps with the stimulation of contractions during childbirth and activates the injection of milk when a baby suckles on the breast. Vasopressin, which is also known as arginine vasopressin (AVP) helps with the conservation of water to take the reabsorption of the water away from the kidneys.
The Adrenal Glands
Located at the top of the two kidneys, the adrenal glands are separated into two parts: the medulla (the inner layer) and the cortex (the outer layer). The cortex is responsible for the production of the corticosteriods, such as cortisol (hydrocortisone). These hormones increase the levels of glucose in the blood and reduce the amount that is in the adipose tissue and muscles. Cortisol is important when dealing with stress, physical trauma and emotional issues.
The medulla produces noradrenaline and adrenaline, which are used to increase blood pressure and heart rate when the body is stressed. It brings out the “fight or flight” response – the survival instinct.
The Thyroid Gland
This gland is separated in two parts and is located just underneath the voice box, right at the front of your windpipe. Two hormones – tri-iodothyronine (T3) and thyroxine (T4) are produced by the thyroid and they are known as the thyroid hormones. They are needed during childhood to help with the brain development, along with the body growth and development. Calcitonin is also produced within the thyroid, ensuring that there is a normal level of calcium within the blood.
The Parathyroid Glands
This is a complex system made of four smaller glands, about the size of peas. They are found within the thyroid glands at the four separate corners. They help with the regulation of calcium levels within the bloodstream.
Located below and behind the stomach, in the upper abdomen, the pancreas serves two needs. It helps with digestion by producing certain enzymes and produces glucagon and insulin, which are needed to manage the blood sugar levels.
Insulin is needed to keep the blood sugar levels low. It helps with the formation of glycogen – lipids (fats) and proteins – that are stored elsewhere in the body, such as the muscles, adipose tissue and liver, to use for energy. The glucagon does the opposite by increasing the level of glucose in the blood. Maintaining the right levels of blood sugar is done by the two hormones working together.
The hypothalamus is right inside the brainn and controls the pituitary gland. It is the control room of the whole system and makes sure the other parts do their own job. It also regulates the rest of the system, including blood pressure, sexual behavior, body temperature, heart rate, sleep cycle, eating and drinking patterns and the emotions. If the brain finds out about needed hormonal changes, the hypothalamus secretes the relevant chemicals to suppress or stimulate the production of homrones from the pituitary gland.
The Thymus and Pineal
The thymus is partially responsible for the development of the immune system and processesthe lymphocytes in babies. The pineal gland is inside the brain and helps with the sleeping cycle by secreting melatonin. When there are disturbances in the hormone, jeg lag happens, which is something many travellers suffer from when travelling long distances. This hormone also helps with the sex gland development in males and females.
The Testes and Ovaries
These are the sex glands and produce the hormones and cells for the body’s development, the reproduction and the sex characteristics on the male and female bodies. There are three hormones produced: progestogens, estrogens and androgens, which includes the testosterone.
Estrogens are required for the development and functionability of the breasts and female genitialia. They are linked to the start of the mensutral cycle and the production stops during menopause. Men also produce this hormone within the testes but this is at a much lower level than in women.
During the menstrual cycle, the ovaries produce progestogens. These are also produced during prengnacy in the placenta. They help with improving the uterus lining to get it ready for pregnancy and stimulate the mammary gland, along with estrogens, to make sure the breasts are ready for lactation. The main hormone is progesterone.
Steriod testosterone is produced within the testes and is the main androgen. Some of this is produced in women but not as much as in men. Testosterone is produced during pregnancy to help with the development of the male sex organs. It promotes the growth of those sex organs in men and stimulates the characteristics associated with men, including facial hair growth and the deeper voice. It also helps with the regluation of the prodction of sperm and sexual potency in later life.
The Role of the Endocrine System in Human Health
There are many symptoms linked to an imbalance in the hormones and certain symptoms are linked to endocrine system problems. Excessive thirst, weight loss that is unexplained and frequent urination are all signs of an extremely common disorder, diabetes mellitus. Most of the endocrine disorders, such as diabetes, are treated by the primary care doctors although there are times that the doctor will need to make the first diagnosis and then pass the case onto an endocrinologist.
Most of the disorders – although not all – are due to a particular hormone being under- or over-produced. When there is too little or not enough hormone, it can be harmful to the human body. The levels of the hormones are regulated by the endocrine organs and offer feedback, similar to the way that a thermostate works in the household. When there is too little of the hormone, the system will tell the certain part of the body to make more and vice versa. For the body to properly function a tight control of the levels is required.The homrones are secreted straight into the bloodstream by the organs and use proteins to bind them so they can travel throughout the body.
Common Endocrine Disorders and Diseases
Two of the most common reasons for endocrine disorders are problems with the levels of the hormone production and because the tissues are not able to respond properly to the hormones. The disorders linked to the production levels are separated into two different groups: hyperproduction, where too much is produced, and hypofunction where too little is produced. The following disorders are linked to the endocrine system:
This is separated into Type 1 and Type 2 diabetes. The first is an autoimmune problem where the cells that produce insulin are destroyed by the immune system. The pancreas is unable to make enough or any insuline. Young adults and children are more likely to develop it but it can be developed at a later age. Some of the common symptoms are:
- Extreme fatigue
- Unexplained weight loss
- Increased thirst
- Frequent urination
- Blurred vision
There is no cure for Type 1 diabetes and insulin is the only treatment, introduced in 1921.
90%-95% of cases of diabetes is Type 2. This is often associated with those who are overweight and usually develops after the age of 40. While the pancreas can produce insuline, the body cannot effectively use it and is often resistant to it. After developing the problem, the body will try to help it by decresing the production of insulin tohelp with maintain the glucose homeostasis (this also happens with those who are Type 1 diabetic). The symptoms are gradual and nclude:
- Frequent urination
- Increased thirst
- Blurred vision
- Weight loss
- Sores/wounds that take time to heal
- Frequent infections
Biguanides and thiazolidinedions are used to help control the resistance to insulin. Research has also shown that it is possible to halt or slow down the resistance with the right type of medications and changes to your lifestyle.
This happens when the thyroid gland is unable to produce enough hormone and can become severe after the age of 40. Some of the symptoms are:
- Weight gain
- Mental sluggishness
- Lethargy and fatigue
- Intolerance to the cold
At birth, babies can have congenital hypothyroidism, which has many of the same symptoms. Mental retardation is a risk when left untreated. Treatment is the same for all types of hypothyroidism, which involves medications to replace the hormones, such as triiodothyrine and levothryoxine.
This happens when the thyroid produces too much of its hormones and is a problem for more women than men. The symptoms include:
- Weight loss
- Heart palpitations
- Intolerance to heat
There is also a case of trembling and protruding eyes for some patients. The treatments are medicines that help slow down the production of the hormone. Some times the thyroid will need to be destroyed or removed using radioactive iodine. Graves’ disease, the autoimmune disorder, is the most common reason for hyperthyroidism.
This is life-threatening when not treated and is when the adrenal gland doesn’t act properly or the immune system has destroyed it. The symptoms are:
- Hyperpigmentation (skin darkens without the sun)
Adequate salt in the diet and corticosteroid hormones are the treatment.
These are two different disorders but have very similar symptoms of:
- Skin that bruises easily
When the body produces too many glucocorticoid hormones, it is known as Cushing’s syndrome. This can also happen due to cancerous and bening tumors on the adrenal glands. When too much adrenocoticotropic hormone is produced, it is Cushing’s disease and is usually due to a benign tumor. Treatments including radioation therapy, surgery, medication to block the glucorticoid hormone production and chemotherapy.
Some of the less known endocrine disorders are:
Hypogonadism is when the sexual maturity is delayed in children and causes infertility due to the follicle stimulating hormone underproduction by the pituitary gland. Gigantism occurs in children and acromegaly in adults due to a tumor on the pituitary gland, which leads to the growth hormone overproducing.
Adipose tissue—This is the connective tissue that stores fat. Droplets of fat distend the cells.
Autoimmune—This refers to a condition where the T-cells or antibodies attack tissue, cells and molecules of a system or organ that produces them.
Electrolyte—This nonmetallic electronic conductor carries a current by ion movement.
Lactation—When the mammary gland, within the breasts, secretes milk.
Lymphocytes—The lymphoid tissue produces these weak cells.
Menopause—Usually between 45 and 50, the menstrual cycle stops naturally.
Menstruation—When the uterus discharges blood. It starts at puberty and is usually in monthly cycles.