Endocrine System: Function, Glands Present in Endocrine System, and Potential Medical Conditions

Our endocrine system is a mesh of glands and organs situated all over the body. Endocrine system resembles the nervous system where it helps in regulating and controlling various functions of the body. The endocrine system uses hormones for communication and other functions.^{(1, 2)}

The function of endocrine system is regulation of various functions of the body via release of hormones. The secretion of hormones occurs by endocrine glands where they travel through the bloodstream to different tissues and organs in the body. The hormones communicate to the tissues and organs about what they should do and how to do it.

Some of the functions of the body which are controlled by the endocrine system are: Heart rate, metabolism, appetite, blood pressure, body temperature, sexual function and reproduction; growth and development; sleeping and waking cycles.

A gland is a form of organ, which produces and releases substances required by the body to function. Two types of glands are present in the body:

• Endocrine glands that release the hormones into the bloodstream directly.
• Exocrine glands, such as sweat glands and lymph nodes; these are not a part of the endocrine system.

The endocrine glands produce, store and release the hormones. Each endocrine gland is responsible for producing one or more than one hormone where they target particular tissues and organs in the body.

The endocrine system has the following glands:

• Pituitary Gland ⁽⁴⁾: The pituitary gland is present under the hypothalamus gland and it produces hormones, which are responsible for reproduction and growth. The hormones released from pituitary gland are also responsible for regulating the function of other endocrine glands.
• Hypothalamus Gland ⁽³⁾: There are some people who do not think of it as a gland, but the hypothalamus gland is responsible for producing many hormones, which control and regulate the pituitary gland. Hypothalamus gland also regulates many functions of the body, such as body temperature, sleep-wake cycles and appetite along with managing functions of other endocrine glands.

Thyroid Gland is present in the front part of the neck and plays an important role in metabolism.

Parathyroid Gland⁽⁵⁾ is also present in front side of the neck and is important for maintaining control of calcium levels in your bones and blood.

Thymus Gland is situated in the upper torso and is active until puberty and produces hormones, which are needed for the development of T-cells, which are a form of white blood cells.

Pineal Gland⁽⁶⁾ is located in the center of the brain and is needed for managing the sleep-wake cycles.

Adrenal Gland is located on top of each kidney and they produce hormones which are required for regulating certain functions like heart rate, blood pressure and stress response.

Pancreas is present behind the stomach in the abdomen and its function is to control the levels of blood sugar.

There are some endocrine glands which also perform some non-endocrine functions, such as the testes and ovaries not only produce hormones, but also produce sperm and eggs which constitute the non-endocrine function.

The endocrine system uses hormones to transmit messages to tissue and organs in the body. After the hormones are released into the bloodstream, they travel to their target tissue or organ that contains receptors which will identify and react to the particular hormone.

Some of the hormones produced by the endocrine system are:

• Adrenaline is the hormone released by the adrenal gland and it is responsible for increasing heart rate, metabolism and blood pressure in response to stress.
• Cortisol is also produced by the adrenal gland and this hormone plays a role in how a person responds to stress.
• Aldosterone is the hormone released by the adrenal gland and is responsible for controlling the salt and water balance in the body.
• Dehydroepiandrosterone sulfate (DHEA-S) is released by the adrenal gland and it helps with the growth of body hair and production of body odor during puberty.
• Follicle-stimulating hormone (FSH) is produced by the pituitary gland and it is responsible for controlling the production of sperm and eggs.
• Estrogen is the female reproductive hormone produced by the ovary and helps in regulating the menstrual cycle, development of female sexual features; maintaining the pregnancy; and in sperm production
• Luteinizing hormone (LH) is released by the pituitary gland and it controls the production of testosterone and estrogen along with ovulation.
• Insulin is produced by the pancreas and it helps in decreasing the blood sugar levels.
• Glucagon is produced by the pancreas and this hormone is responsible for increasing the levels of blood sugar.
• Melatonin is produced by the pineal gland and it is responsible for managing and regulating the sleep-wake cycles
• Oxytocin is released by the pituitary gland and it helps with childbirth, lactation and bonding between mother-child.
• Thyroid hormone is released from the thyroid gland and it is responsible for controlling many functions of the body, such as the metabolism rate and energy levels.
• Parathyroid hormone is released by the parathyroid gland and is responsible for controlling the levels of calcium in blood and bones.
• Prolactin is released by the pituitary gland and it encourages the production of breast-milk.
• Progesterone is released by the ovary and it helps in preparing the body for pregnancy after fertilization of an egg.

There are times when the level of hormones fluctuates and it can increase or decrease. When this occurs, it affects a person’s health in different ways. The symptoms a person experiences depends on the hormone which is not in its normal levels. Given below are some conditions which change your hormone levels by targeting the endocrine system.

Hyperthyroidism⁽⁸⁾ occurs when there is excessive production of thyroid hormone by the thyroid gland resulting in various things including autoimmune diseases. Symptoms of hyperthyroidism are: Nervousness, fatigue, problems withstanding heat, weight loss, diarrhea, rapid heart rate and difficulty in sleeping.

Treatment of hyperthyroidism depends on the severity of the condition and its underlying cause and consists of radioiodine therapy, medications and surgery.

Graves’ Disease⁽⁹⁾ is a common form of hyperthyroidism and is an autoimmune disorder. In patients suffering from Graves’ disease, the body’s immune system attacks the thyroid gland resulting in increased production of thyroid hormone.

Hypothyroidism⁽¹⁰⁾ occurs when there is insufficient production of the thyroid hormone by the thyroid gland. There are many causes for hypothyroidism. Symptoms of hypothyroidism are: Weight gain, fatigue, constipation, dry hair and skin; problem withstanding cold; irregular periods; decreased heart rate and fertility issues.

Treatment for hypothyroidism consists of medication to supplement the thyroid hormone.

Addison’s Disease⁽¹¹⁾ develops when there is insufficient production of cortisol or aldosterone by the adrenal glands. Symptoms of Addison’s disease are: Weight loss, fatigue, pain in the abdomen, reduced blood sugar, irritability, diarrhea, nausea or vomiting, irregular periods and craving for salty foods Treatment for Addison’s disease consists of medications to replace the hormones which the body isn’t producing.

Cushing Syndrome⁽¹²⁾ occurs from increased levels of the cortisol hormone. Symptoms of Cushing syndrome are: Irregular periods, weight gain; deposit of fat on the face, shoulders and trunk; presence of stretch marks; bruising easily due to thin skin; delayed healing of scrapes, cuts and insect bites; decreased libido and fertility in men.

Treatment of Cushing syndrome depends on its cause and consists of radiation therapy, medications and surgery.

Diabetes⁽¹³⁾ is a condition in which the blood sugar levels are high. Patients with diabetes have excessive glucose in their blood. Diabetes is of two types of: Type 1 diabetes and type 2 diabetes.

Symptoms of diabetes are: Increased thirst or hunger; fatigue; irritability; frequent urge to urinate and increased susceptibility to infections. Treatment for diabetes consists of monitoring the blood sugar levels, medications and insulin therapy. Lifestyle changes include getting regular exercise and following balanced diet.

Hypogonadism⁽¹⁴⁾ is another common hormonal condition seen in older men and sometimes in women. Hypogonadism occurs as result of decreased production of testosterone, which is a sex hormone. Symptoms of Hypogonadism are decreased libido, reduced muscle mass; depression, dressed energy; erectile dysfunction and increased irritability. Treatment for hypogonadism consists of improving the levels of testosterone with lifestyle changes and testosterone replacement therapy.

Polycystic Ovary Syndrome (PCOS)⁽¹⁵⁾ develops as a result of unbalanced reproductive hormones in females with the presence of cysts on the ovaries. Females suffering from PCOS will not have an egg released every month or the egg may not develop as it should upon its release.

Symptoms of PCOS are: Fertility issues, irregular periods, acne, formation of cysts on the ovaries; hirsutism, weight gain, thinning hair and skin tags.

Treatment for PCOS is aimed at alleviating the symptoms. Treatment consists of medications, such as metformin and birth control along with lifestyle changes to include more nutritious food and losing excess weight.

Osteoporosis⁽¹⁶⁾ is a condition where there are changes in bone tissue and abnormal loss of bone mass. The cause of Osteoporosis is varied, but common causes include reduced lowered levels of estrogen in women and decreased levels of testosterone in men. These decreased hormone levels can be a result of aging along with other medical conditions. Symptoms of Osteoporosis include bone injuries and fractures, which can occur from lifting, minor falls and even coughing. Treatment for osteoporosis is aimed at stopping or slowing the bone loss by following the right diet, medications and exercise.

Acromegaly⁽¹⁷⁾ is a rare disease which develops when there is excessive production of growth hormone from the pituitary gland. Acromegaly can be often seen in middle-aged people and causes growth of organs, cartilage, bones and certain tissues. Symptoms of acromegaly are: swollen ears; swollen nose; swollen hands and feet; a deeper voice; joint pain; increase in body odor and sweating.

Treatment for acromegaly consists of medications, surgery and radiation therapy.

The endocrine system is a complex collection of organs and glands which are responsible for regulating different functions of the body by releasing hormones produced by the endocrine system. For good health, it is important that the levels of hormones stay in the normal range. When there is any increase or decrease in any of the hormones produced by the endocrine glands, then it can cause a variety of health issues.

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