Our Great Glandular System: Facts, Functions, and Disorders
Do you know that the glandular system regulates your moods, whether happy or sad? Yes, various glands release some chemicals known as hormones to control most bodily functions. Some hormones then trigger of control some emotions or moods depending on the chemicals.
Hormones are part of the glandular system that act as chemical messengers for bodily reactions and functions. The glands are the custodians of different kinds of hormones that they release by secretion as chemicals into the circulatory system. The blood vessels in the circulatory system then distribute the hormones all over the body to the target areas for different functions.
Glandular System Definition
The glandular system is a combination of glands that produce and discharge hormones responsible for the functions of body cells and organs.
An unhealthy glandular system can affect your normal bodily functions. For instance, the gonad glands (ovaries and testes) hormones control the reproductive system. Developing to puberty can never be if the hormones of gonad and pituitary glands are insufficient.
Body systems also depend on the glandular system for their activities. For instance, the digestive system relies on the pancreas gland for the digestive enzyme to break down some types of food.
The entire glandular system is divided into two major parts, which are Endocrine glands and Exocrine glands.
What are Endocrine Glands?
Endocrine glands are ductless glands that secrete their hormones directly into the bloodstream for circulation and release to the targeted area.
The major endocrine glands include the pituitary, hypothalamus, and pineal which are situated in the brain. You have the thyroid gland and parathyroid inside your neck. In the lungs, you have the thymus gland, and in your kidneys the two adrenal glands. The pancreas gland lies across your abdomen. In your pelvis are the gonads, the ovaries (women) and testes (men) glands.
Endocrine Glands Functions. Each gland has a unique function according to the secretion of the hormones. Some glands produce hormones that control and regulate the performance of other glands. It means then, that the entire glandular system is a network of glands that depend on one another for their functions.
1. Hypothalamus Gland
The hypothalamus gland is part of the brain that maintains homeostasis (internal balance of the body). It is situated between the pituitary gland and the thalamus in your brain. The gland links the glandular system to the nervous system and regulates the secretion of pituitary hormones by the pituitary gland.
The hypothalamus gland produces hormones known as neurohormones to regulate the pituitary hormones.
The gland plays other roles in the body, such as regulating body temperature, body fluids, sex drive, appetite, heart rate, and blood pressure.
Hypothalamic Disease - A head injury that could affect the hypothalamus can cause hypothalamic disease.
Hypothalamic amenorrhea - It is a hypothalamus disease that can affect a regular menstrual period. In severe conditions, it can lead to infertility.
2. The Pineal Gland
The pineal gland, once known as the 'third eye,' is a tiny gland located inside your brain between the two brain hemispheres. People call it the third eye because of its eye-shape. The gland remains a mystery to scientists and researchers with little knowledge about it.
The pineal gland produces melatonin hormones. The light regulates the secretion of melatonin to form the sleeping pattern. The melatonin hormones increase when dark and lessen in the day time. Some of the hormone's functions are:
Circadian rhythm – The hormones regulate your sleep-wake patterns known as a circadian rhythm. It is your brain clock that sets the alarm in your brain to wake you up when it is time.
Mental health – Sleep tones your mental health. A decline in melatonin production can cause some mental health conditions such as stress and depression for lack of enough sleep.
Regulate reproductive hormones – Melatonin hormone regulates the reproductive hormones for timely processes such as puberty and pregnancy.
Pineal Gland Disorders
There is no evidence of melatonin deficiency or excess disorders. However, some sleep-deprived disorders such as insomnia, depression, stress, and aging can make up the list of pineal gland disorders. The pineal gland is an 'ongoing' study case, and probably scientists and researchers might reveal more about it in the future.
3. The Pituitary Gland
The pituitary gland is in the brain located at the base of the hypothalamus gland and behind the nose bridge. Besides being a tiny gland the size of a pea, the pituitary gland is a powerful 'master gland.' The gland regulates the functions of almost all other hormonal glands.
The pituitary gland has three sections, the anterior, intermediate, and posterior.
Anterior Pituitary Gland
The anterior part of the pituitary gland is part of the hypothalamus gland through the connection of some blood vessels. The hypothalamus commands hormones production and secretion of the anterior pituitary gland into the bloodstream when a need arises.
The anterior pituitary gland secretes six hormones. Two of the hormones control non-endocrine glands. The hormones are:
Growth hormone (GH) – regulating body growth by stimulating division and growth of body cells, bones, and muscles.
Prolactin (PRL) – The hormone stimulates the production of milk for breastfeeding mothers.
The remaining four hormones control other hormonal glands in secreting their hormones. The four anterior pituitary gland hormones are:
Thyroid-stimulating hormone (TSH) – stimulates the secretion of thyroid hormones by the thyroid gland.
Adrenocorticotropin hormone (ACTH) – stimulates the secretion of steroid hormones by the adrenal gland.
The follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) – The two follicle hormones that regulate the secretion of reproductive hormones.
Posterior Pituitary Gland
The posterior pituitary gland is the custodian of two hormones produced but not controlled by the hypothalamus gland. The hypothalamus gland produces the two hormones and then sends them to the pituitary gland for storage and secretion when needed. The two hormones are:
Anti-diuretic hormone – maintaining the right amount of body water and blood pressure.
Oxytocin – Supports prolactin hormone in milk production. It also stimulates uterus contractions during childbirth.
Intermediate Pituitary Gland
Melanocyte-stimulating hormone (MSH) – Stimulates the skin cells in melanin production.
Pituitary Gland Disorders
Some of the pituitary gland disorders include:
Hypopituitarism - The deficiency of pituitary gland hormones can cause pituitary failure or hypopituitarism. The condition can affect most of the body functions, including sexual activities.
Pituitary adenomas - The pituitary gland cells can overgrow to cause a noncancerous tumor due to accidental DNA changes. According to Cleveland Clinic, the condition is rare for young people below 20 years and common to people between ages the 30s and 40s and mostly women.
Cushing Disease - Pituitary adenomas can lead to Cushing disease due to over-producing adrenocorticotropic hormone (ACTH).
4. Thyroid Gland
You have your thyroid gland at the neck on the lower front part. The gland has a butterfly shape because of the two lobes extending on each side and connected in the middle by isthmus or bridge. The thyroid secretes various hormones for different functions. One of the hormones is thyroxine or T4.
The significant function of the thyroid hormones is maintaining the growth of the nervous system and brain in children.
The hormones also manage the heart rate, blood pressure, reproductive functions, digestion, and muscle toning.
Excess secretion of thyroid hormones (hyperthyroidism) or thyroid hormone deficiency (hypothyroidism) can lead to various disorders. Some of the common thyroid disorders are:
Goiter - Enlargement of the thyroid gland caused by either insufficient iodine intake which is hypothyroidism, or some nodules formation in the gland.
Thyroid nodules - Most of the thyroid nodules are noncancerous and often don't cause any symptoms if not severe. Iodine deficiency or overgrown thyroid tissue can lead to such nodules.
Hashimoto's disease - Also known as Hashimoto's thyroiditis is prevalent among women than men. It is an autoimmune disease, which affects the thyroid hormones secretion causing hypothyroidism.
Graves' disease - Graves' disease is also known as toxic diffuse goiter. It is an immune system disorder the can result in over-secretion of thyroid hormones or hyperthyroidism. The disorder is most common in women over 40 years.
Thyroid Cancer - Thyroid cancer is a generic name of four main types of cancer of the thyroid, which are papillary, follicular, medullary, and anaplastic. The thyroid four cancer types differ according to their aggressiveness. The most aggressive of the four is medullary, which can spread fast to other lymph nodes.
The most common and curable type of thyroid cancer is papillary with a high rate of survivors. The cancer type takes over 80% of all thyroid cancer patients. In 2019 an estimated figure of thyroid cancer new cases in the US alone was 52,070. The number translates to a rise of 3% from previous estimates.
5. Parathyroid Glands
The four tiny parathyroid glands are each the size of one rice grain with a diameter of about 3 to 4mm. They sit in pairs on the surface of each side of the thyroid gland. The function of the parathyroid hormone is to maintain a proper balance of body calcium.
The parathyroid gland secretes more hormones in the bloodstream when calcium is low, an indication to the bones to release more calcium. The kidneys also get the hormone message to release more vitamin D for calcium absorption through the small intestines. The parathyroid glands reverse the process if the calcium level rises to reduce the secretion of parathyroid hormone ultimately.
Parathyroid Glands Diseases
Hyperparathyroidism - Due to various reasons, the parathyroid can continue secreting and releasing parathyroid hormone (PTH) into the bloodstream even when the calcium level is high. Excessive secretion of PTH can cause other conditions such as kidney stones, osteoporosis, pancreatitis, heart disease, and others.
Hypoparathyroidism - It is a condition of low parathyroid hormone. The parathyroid glands can, for some reason, fail to produce enough hormones even when it is necessary. The problem can then lead to a low calcium level in the blood. The condition can then affect various body functions, including the nerves and the muscle.
6. Thymus Gland
The thymus gland is a short-lifespan gland. It is present and at its largest at birth and remains active up to the age of puberty. From thence, the gland starts to deteriorate and shrink. As you age, the thymus gland is no more, and in its place, some fatty tissue grows to replace it.
The thymus gland is located in between your two lungs at the chest's upper anterior behind the breastbone. The gland is part of both the glandular system and the lymphatic system. It produces thymosin hormone, which stimulates the production of T-cells, a type of white blood cells.
The T-cells are part of the immune system that defends the body against attacks by bacteria, viruses, and other harmful pathogens.
Thymus Gland Disorders
Myasthenia Gravis (MG) - The myasthenia gravis is an autoimmune disease that weakens the voluntary muscles. An abnormally large thymus gland can excessively produce antibodies creating autoimmunity. The antibodies attack and destroy the muscle cells and hence impair and cause muscle fatigue.
Thymic Neoplasms - Thymic neoplasms are various kinds of thymus tumors. An autoimmune condition, such as myasthenia gravis, can cause thymic neoplasms. Two of the thymic neoplasms are:
Thymoma - Thymoma is a thymus tumor that originates from its surface on the lining cells. In most cases, this type of tumor is benign and hence does not spread elsewhere in the body.
Thymic carcinoma – It is a rare thymus gland cancer and yet an aggressive one. The disease is asymptomatic, meaning it does not reveal symptoms.
The thymus cancer can surprise a doctor on a routine check to find cancer cells originating from the gland. A few indications of thymic carcinoma are coughing, chest pain, and shortness of breath.
Pure Red Cell Aplasia (PRCA) - Pure red cell aplasia is an autoimmune disease that reduces the red blood cell precursors in the bone marrow. One of the causes of the disease is the presence of thymomas, a tumor of the thymus gland. A thymomas condition, whether in its early stage or advanced, can cause PRCA.
7. Adrenal Glands
You have two adrenal glands that sit on top of each of the two kidneys. The triangular-shaped glands have two different sections, the outer and the inner part. The outer one is cortex while the inner is the adrenal medulla. Your adrenal glands have an outer cover as a protective layer called the adipose capsule.
The hormones produced by your adrenal glands are adrenal, aldosterone, and cortisol.
Adrenal – A hormone produced to cope and deal with stress and alarm responses to "fight or flight.'
Aldosterone – A hormone that balances potassium and sodium in your blood. The two electrolytes balance body fluids and control blood pressure.
Cortisol – A hormone that helps you to deal with stress, control heart rate and blood pressure, directs the immune system, and metabolism.
Adrenal Glands Disorders
Any irregularity in hormones secretion by the adrenal glands can lead to hormonal imbalances. The glands can either secrete too much or too little of the hormones to cause different disorders.
Adrenal insufficiency - It is also known as Addison disease. The adrenal glands fail to produce some essential hormones or produce insufficient hormones which can lead to body malfunctions and other effects.
The condition is a result of an autoimmune problem. Your immune system attacks and damages the adrenal cortex interfering with hormones production.
Congenital Adrenal Hyperplasia - Congenital adrenal hyperplasia is an adrenal disease present at birth that affects the adrenal cortex and hence the production of cortisol hormone. A child inherits a group of genetic disorders while still developing in the womb causing the CAH.
The condition affects the healthy child growth and body development after birth, balancing body fluids, and regulating blood pressure.
The CAH (congenital adrenal hyperplasia) has two forms depending on the severity of the condition. The classic type is a severe CAH, while the non-classic is a milder condition. The classic kind of CAH can affect the child's body development.
Doctors detect the CAH classic type in an infant by several symptoms. Some significant signs of CAH classic type are unregulated blood pressure, body fluids imbalance, and abnormal development of genital organs.
Adrenal Cancer - Adrenocortical carcinoma - is a type of cancer that begins at the cortex, a section of the adrenal gland. It is common in children or adults between ages 40 and 50 but in rare cases.
Not all adrenal tumors turn out to be cancerous. Some of the growths may be noncancerous or benign. The noncancerous and malignant tumors can be similar. But, to ascertain the condition of the tumor, you should go through various tests.
Pheochromocytoma - Adrenal cancer can also develop in the adrenal medulla. The adrenal medulla cancer is known as pheochromocytoma. The cause of tumor growth is the over-production of noradrenaline and adrenaline hormones.
Some of the adrenal cancer symptoms are abdominal pain, severe periodic headache, increased heart rate, and high blood pressure. If you notice some of the said symptoms, seek early observation and treatment.
8. The Pancreas Gland
The pancreas gland plays two roles. It functions as both endocrine and exocrine gland, the reason why it is known as heterocrine gland. The gland is located in the abdomen's upper left side. The islets of Langerhans are the cells that produce and release hormones of the pancreas.
The islets which are in clusters form have two major types of cells that produce both insulin and glucagon hormones. The cells that produce insulin are the beta cells and for glucagon, they are alpha cells.
Insulin – Insulin is a hormone responsible for regulating the use and storage of glucose and fat. The hormone insulin signals body cells and muscles to absorb glucose for energy.
If the blood contains excess sugar more than the cells require, insulin hormone signals the liver to store the excess. The liver changes the glucose to glycogen for storage. Insulin, therefore, controls blood sugar levels from getting high.
Glucagon – Another hormone of the pancreas gland. The hormone has a reverse role of the insulin. It prevents the level of blood glucose from getting too low. The hormone signals the liver to convert the glycogen in storage to glucose when is very low. The glucose then enters the bloodstream for circulation to the body cells.
Acute Pancreatitis and Chronic Pancreatitis - Acute pancreatitis is an inflammation disease of the pancreas that happens suddenly but subside fast to last only a few days. Chronic pancreatitis is a persistent pancreas inflammation that progresses for a long time. The chronic type of pancreatitis can leave behind severe damage of the pancreas by destroying organ cells.
Both acute and chronic pancreatitis have almost similar symptoms. One of the symptoms is severe abdominal pain, which gets worse after having a meal.
Common causes of the two disorders are alcohol abuse, cigarette smoking, and gallstone blocking duct sphincter.
Pancreatic Cancer - Pancreatic cancer is a prevalent type of cancer, taking 12th and 11th positions of cancer cases in men and women consecutively. In 2018, new cases of pancreatic cancer in the world were 460,000, according to the World Cancer Research Fund (WCRF).
Two of the pancreatic cancers are:
Adenocarcinoma – A tumor that begins at the ducts affecting the pancreatic gland cells.
Ampullary carcinoma – Though rare cancer, it can occur in the ampulla, at the joint of both pancreatic and bile duct.
Gonads are endocrine glands that produce primary reproductive hormones for both males and females. The male gonads are the testes while the ovaries are the female gonads. The gonad produces steroid-type hormones for the reproductive system.
The Testes Gonads
The testes gonad gland produces androgen hormones such as testosterone and a small amount of estrogen.
The male hormones are responsible for sperm cell production, maturation and maintain and regulating sex arousal. Stimulating sex organs development and functioning.Also, stimulating the formation of male sex characteristics such as the change of voice, face hair growth, and others.
The Ovaries Gonads
For the female, the ovaries produce estrogen and progesterone female hormones. The hormones responsibilities are:
Estrogen – The hormone is responsible for secondary female sexual characteristics. Some of the characteristics are the growth of breasts, pubic hair, uterus, vagina, and endometrium. Regulation of menstrual cycle, egg maturation, fat distribution, and others.
Progesterone – The corpus luteum release progesterone hormones after ovulation. The hormone prepares the uterus lining in readiness for fertilized egg implantation. The progesterone continues to be active for seven to nine weeks of pregnancy.
Hypogonadism - Hypogonadism is a disease of both male and female gonads (sex glands). You can also refer to the disorder as gonad deficiency. The condition can cause low sex hormones or zero hormones production.
Such a case can also be called andropause or low serum testosterone in the male.
The gonad disorder can affect reproduction functions such as menstrual circle in female and sperm production in the male.
Autoimmune conditions or severe viral infections such as HIV can be the cause of hypogonadism.
What are the Exocrine Glands?
The exocrine glands are glands that use ducts to secrete chemical substances directly on the target surfaces within or outside the body.
Some of the exocrine glands are:
- Sebaceous (for hair and skin oils)
- Ceruminous (for waxing ears)
Their secretion methods classify the exocrine glands into three groups:
Holocrine glands – The cell of the holocrine gland breaks to release the stored substance in the duct. The gland then replaces the destroyed cell with a new one. An example of holocrine glands is the skins sebaceous glands and eyelids meibomian glands.
Merocrine glands – The glands release substances by pores or cellular channels to the duct and eventually to the surface. Examples of merocrine glands are salivary, sweat, lacrimal (tears), and pancreatic.
Apocrine glands – The method of substance secretion by apocrine glands is through snipping off or loss of part of the secretion cell. The secretion is then released in spurts through the ductal system onto the surface. Although the method damages the secretion cell, it does not annihilate it like in the holocrine glands secretion method.
Some examples of apocrine glands are ceruminous glands (ear), moll's glands (eyelids), and mammary glands (breasts).
Exocrine Glands Disorders
Some of the exocrine glands' disorders include:
Sjögren's syndrome (SS)
It is a chronic inflammatory disease that affects the salivary and tears glands. The autoimmune and systemic disorder weakens the function of the two glands inhibiting the secretion of mucus and hence causing dry eyes, mouth, and also drying other mucous membranes.
SS can develop by itself or accompanied by another disease. When alone, the Sjögren's syndrome is classified as primary. When accompanied by another condition such as rheumatoid arthritis or Hashimoto thyroiditis, it is called secondary Sjögren's syndrome.
The disease can damage the secretion cells and ducts, leading to other disorders such as inflammation of cornea and conjunctiva, mouth infection, chewing and swallowing difficulty, and cavities.
Cystic fibrosis (CF)
Cystic fibrosis is a genetically inherited disease of the exocrine glands. The disorder severely damages cells that produce sweat, mucus, and digestive juices. The natural secretion of such cells appears slippery and thin. In CF, the secretion is sticky and thick.
The danger of such secretion is to plug up the ducts, causing more damage to organs such as the lungs and pancreas.
Persistent cough with thick mucus, wheezing, stuffy nose, and recurring lung infection are some of the CF symptoms.
Benign prostatic hyperplasia (BPH)
One of the worst fears in men is benign prostatic hyperplasia. The BPH condition has several causes among them hormonal imbalance. The imbalance can be a decline in releasing testosterone hormones by the testes.
The testosterone is converted into dihydrotestosterone in the prostate and testes by enzyme 5-AR (5-alpha-reductase). DHT is useful for developing and maintaining the prostate gland. Also, the hormone regulates the prostate's functions.
Aging can reduce the production of testosterone hormone, which then can cause hormonal imbalance in men and therefore causing BPH.
The glandular system is a crucial factor in the entire body's operations and processes. For instance, it is the responsibility of the glandular system to guard the electrolytes balance outside and inside the cells carefully.
The glandular system takes care of nutrients and fuels homeostasis for body metabolism. Insulin and glucagon regulate levels of blood sugar in the body to store the abundance and avail it when needed.
The endocrine system controls the reproductive system in both sexes through sexual hormones, the timely menstrual cycle, the timely sperm ejaculation and fertilization, and every process of the reproductive system. The main hormones for the reproductive system are estrogen and testosterone.
Various hormones and the nervous system influence the growth and development of a child from the fetus stage to adulthood through signals. The hormones responsible are pituitary growth hormone, testosterone for boys and estrogen for girls, thyroid hormone, and pituitary gonadotropic hormones (stimulating sex gland).
Supporting Glandular Health
Support your healthy glandular system for a functional body. Maintain your weight, eat a healthy diet, exercise, and schedule regular health checkups for overall health.
Editor: Yvonne Dollard Perc
Research Assistant: Elizabeth Njuguna
Designer: Sherry Robb
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This article is intended for educational purposes and the information contained within is not intended to treat, diagnose or cure any disease or health problem. Please seek appropriate medical attention for any health complaints. We cannot take responsibility for your health care decisions. Our intent is only to offer health information to help you with your search for better health.