• Pineal Gland
• Pituitary Gland
• Pancreas
• Ovaries
• Testes
• Thyroid Gland
• Parathyroid Gland
• Hypothalamus
• Adrenal Glands

1. What Is Pineal Gland?

The pineal gland is a small endocrine gland which shape looks like a pinecone and is located in the middle of the brain.

The pineal gland is made of cells known as pinealocytes that secrete the hormone melatonin involved in the control of the wake-sleep pattern [2].

2. What Is Pituitary Gland?

The pituitary gland or hypophysis is a gland a size of a pea that sits on a saddle-shaped bony structure known as sella turcica in the middle of the brain.

The pituitary gland is divided into the anterior lobe, intermediate lobe, and posterior lobe.

The anterior lobe secretes several hormones and polypeptides involved in growth, reproduction, stress, pain, and metabolism:

• Adrenocorticotropic hormone (ACTH)

This hormone stimulates the adrenal gland to secrete glucocorticoids, mineralocorticoids, and sex corticoids.

• Thyroid-Stimulating Hormone (TSH)

This hormone stimulates the thyroid gland to secrete thyroid hormones, thyroxine (T4), and triiodothyronine (T3).

• Follicle-Stimulating Hormone (FSH)

This hormone is involved in regulating the growth of the reproductive system by targeting the gonads (ovaries and testes).

• Luteinizing Hormone (LH)

This hormone promotes the production of sex hormones by the gonads.

• Growth Hormone (GH)

This hormone is involved in the metabolism of carbohydrates and lipids by regulating the function of the liver adipose tissue.

• Prolactin

This hormone stimulates the ovaries to secrete estrogen and progesterone and the mammary glands to produce milk.

• Beta-endorphin

Beta-endorphin is an endogenous opioid that binds and blocks opioid receptors resulting in the inhibition of pain perception.

The intermediate lobe of the pituitary gland secretes the melanocyte-stimulating hormone (MSH) also known as melanotropin.

• Melanocyte-Stimulating Hormone (MSH)

MSH stimulates the production of the skin and her pigment, melanin through a process known as melanogenesis.

The posterior lobe of the pituitary gland does not produce hormones but rather stores and secrete the hypothalamus hormones oxytocin and vasopressin.

• Oxytocin is a hormone that acts on other parts of the brain to regulate social bonding, on the mammary gland for milk ejection, and on the uterus for cervical dilatation during labor.

• Vasopressin is a hormone that acts on the kidney to reabsorb free water which is recirculated in the blood.

3. What Is Pancreas?

The pancreas is an organ of the digestive system situated behind the stomach and has both endocrine and exocrine functions.

As an endocrine gland, the pancreas secretes inulin, glucagon, somatostatin, and pancreatic polypeptide.

• Insulin is a hormone produced by the beta cells of the pancreatic islets and is involved in the absorption of blood glucose be the liver, adipose tissue, and muscles.

• Glucagon is a hormone produced by the alpha cells of the pancreas and is involved in converting stored glycogen into glucose that is released in the bloodstream.

• Somatostatin is an inhibitor of the secretion of insulin, glucagon secretion, prolactin, growth hormone, thyroid stimulating hormone, and adenyl cyclase (enzyme).

• Pancreatic polypeptide is involved in the storage of glycogen by the liver and in the regulation of pancreatic secretion in the gastrointestinal system.

The exocrine function of the pancreas is associated with the secretion of the pancreatic juice that helps with the digestive process.

4. What Are Ovaries?

The ovaries are organs of the female reproduction system involved in the regulation of the menstrual cycle and fertility.

The ovaries secrete the hormones estrogen, progesterone, androgen, and inhibin.

• Estrogen are sex hormones that promote the development of the female reproductive system and secondary sexual characteristics such as breast and thickening of the inner layer of the uterus.

• Progesterone is a sex hormone involved in the regulation of female reproductive systems, such menstrual cycle, pregnancy, breastfeeding, and male reproductive system through its role in spermatogenesis and testosterone production.

• Androgens are involved in libido and sexual arousal in female and are precursors of estrogen.

5. What Are Testes?

Testes are organs of the male reproductive system which produce sperm, androgen (testosterone)

Androgen is a hormone involved in the development and maintenance of male characteristics (testosterone).

The release of testosterone is regulated by the pituitary gland hormones, follicle-stimulating hormone (FSH), and luteinizing hormone (LH).

6. What Is Thyroid Gland?

The thyroid gland is situated in the neck and produces the thyroid hormones, thyroxine (T4), triiodothyronine (T3), and calcitonin.

Thyroxine (T4), triiodothyronine (T3), and calcitonin are involved in the regulation of cellular metabolism, growth, and heartbeat rate.

7. What Is Parathyroid Gland?

The parathyroid gland is situated in the neck at the back of the thyroid gland and produces the parathyroid hormone involved in the maintenance of calcium and phosphate levels in the body through its effect on the bone, gut, and kidneys.

8. What Is Hypothalamus?

The hypothalamus is a gland at the interface between the nervous system and the endocrine system, represented by the pituitary gland.

The hypothalamus secretes hormones known as releasing hormones that regulate the secretions of hormones by the pituitary gland.

It is divided into three regions, the anterior region (supraoptic), the middle region (tuberal), and the posterior region (mammillary). Each region is involved in the secretion of hormones.

• Gonadotropin-Releasing Hormone (GnRH)

GnRH is secreted by the supraoptic region to stimulate the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by the pituitary gland.

• Vasopressin

• Oxytocin

• Thyrotropin-Releasing Hormone (TRH)

TRH is secreted by the supraoptic region to stimulate the release of thyroid-stimulating hormone (TSH) and prolactin by the pituitary gland.

• Corticotropin-Releasing Hormone (CRH)

CRH is secreted by the supraoptic region to stimulate the release of adrenocorticotropic hormone (ACTH) and beta-endorphin by the pituitary gland.

• Somatostatin

• Growth Hormone-releasing Hormone (GHRH)

GHRH is secreted by the tuberal region to stimulate the release of growth hormone (GH) by the pituitary gland.

9. What Are Adrenal Glands?

Adrenal glands are found on the top of the kidneys and secrete the hormones, epinephrine, (adrenaline), norepinephrine, cortisol, and aldosterone.

• Epinephrine

Epinephrine or adrenaline is involved in regulating blood pressure and smooth muscle constriction.

• Cortisol

Cortisol is a steroid hormone involved in many functions in the human body, the inflammatory response, regulating metabolism, and immune function.

Cortisol mediates the stress response as part of the “fight-or-flight” response mediated by the hypothalamus-pituitary gland-adrenal gland (HPA) axis.

• Aldosterone

Aldosterone is a steroid hormone involved in the regulation of blood pressure and the homeostasis of sodium and potassium plasma levels.

• Norepinephrine

Norepinephrine is a hormone and chemical messenger associated with the “fight-or-flight” response mediated by the hypothalamus-pituitary gland-adrenal gland (HPA) axis.

Conclusion

The endocrine system involves communication and coordination between different glands situated in different tissues and organs. It can be regarded as the body messenger that delivers instructions to control essential functions such as growth, reproduction, metabolism, homeostasis, immune response, and stress response.

The post What are the major glands of the endocrine system? appeared first on .

1. Epidemiology of Chronic Fatigue Syndrome

Based on prevalence estimates from the Institute of Medicine, chronic fatigue syndrome affects around 0.2-2.6% of the global population. It mainly affects adults between 40 and 60 years, with a female predominance [1][2]. It also occurs in children and adolescents; however, it appears to be at a lower rate [3].

2. What Causes Chronic Fatigue Syndrome?

There are several causes of chronic fatigue syndrome including genetic, neurological, immunological, infectious, sleep-related, and psychiatric [2].

A. Is Chronic Fatigue Syndrome a Genetic Condition?

Several studies investigated the association between chronic fatigue syndrome and family genetic history. One of the studies compared the rate of chronic fatigue syndrome (CFS) between 25 individuals with CFS and 36 control subjects and found significantly higher rates of CFS in individuals with CFS relatives [4].

By analyzing data from a chronic fatigue twin registry, other studies found higher rates of chronic fatigue syndrome in monozygotic (identical) compared to dizygotic twins and that a genetic predisposition to chronic fatigue syndrome exists in female twins [5].

However, further investigations are required to confirm the involvement of family genetic history in the etiology of CFS [2].

B. Is Chronic Fatigue Syndrome a Neurological Condition?

Due to the presence of symptoms of fatigue, impaired concentration diminished attention and memory, and headache in cases of CFS, neuropsychological and neuroendocrine studies, were performed by several research groups.

Neuropsychological studies

Although studies tested the capacity of information processing, working memory, and poor learning in CFS individuals, the results showed that these individuals have normal cognitive and global intellectual abilities [6].

Neuroendocrine studies

Abnormalities in the hypothalamic-pituitary-adrenal axis and serotonin pathways were reported in patients with CFS. These individuals had an altered physiological response to stress associated with reduced levels of cortisol, a disorder of central neurotransmitters, and disturbance of the functional relationship between cortisol and central neurotransmitters [7].

C. Is Chronic Fatigue Syndrome an Immunological Condition?

Analysis of the immune system in CFS individuals demonstrated the presence of alterations affecting the function of natural killer (NK) cells and regulatory T and B cells, and higher frequencies of various autoantibodies [8] [9]. However, other studies showed the absence of changes in lymphocyte subsets in CFS individuals [10].

D. Is Chronic Fatigue Syndrome Due to Infections?

Although several studies reported potential associations between CSF and viral infections, such as Epstein–Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus (HHV) 6, HHV-7, HHV-8, human parvovirus B19 (B19V), enteroviruses, lentiviruses, the role of viral infections in CSF etiology have not been confirmed and remains inconclusive [11].

E. Is Chronic Fatigue Syndrome Due to Sleep Disruption?

Although many studies suggested an association between CSF and sleep disturbances using sleep parameters such as slow-wave sleep, apnea-hypopnea index, spectral activity, and multiple sleep latency testing, a recent study showed that the reported results are inconsistent due to subjects’ recruitment decisions, confounding factors, small sample sizes and unconfirmed findings [12].

F. Is Chronic Fatigue Syndrome a Psychiatric Condition?

Several studies suggested that CSF is a psychiatric disorder that originates in CSF individuals who have mood disorders, such as anxiety, and major depression, and somatization disorder which includes symptoms such as headaches, dizziness, generalized pain, bowel movement, and fatigue [13] [14].

H. Is Chronic Fatigue Syndrome Due to Lack of Exercise?

A study showed that CSF individuals have less physical activity than non-CSF individuals, suggesting that the lack of physical activity could aggravate fatigue in CSF patients [15]. Interestingly, another study showed that individuals with CSF who received a graded exercise program had improvements in physical activities and in some cognitive variables [16].

3. How Is Chronic Fatigue Syndrome Diagnosed?

Unfortunately, there is no specific test for CSF, and the diagnosis is based on the observation of symptoms including sleep disturbances, headaches, joint, and muscle pain, disabling tiredness, flu-like symptoms, dizziness, and heart palpitations.

4. How Is Chronic Fatigue Syndrome Treated?

The treatment of chronic fatigue syndrome is symptomatic and involves the use of a graded exercise program to improve physical activity, medications to control sleeping disruptions and pain, and cognitive behavioral therapy to improve cognitive disorders, and behaviors, and to develop coping strategies.

5. Frequently Asked Questions about What Is Chronic Fatigue Syndrome?

What is Chronic Fatigue Syndrome (CFS)?

Chronic Fatigue Syndrome, also known as myalgic encephalomyelitis (ME/CFS), is a complex disorder characterized by extreme fatigue that doesn’t improve with rest and may worsen with physical or mental activity.

What are the symptoms of CFS?

The main symptom of CFS is severe fatigue that lasts for at least six months and is not alleviated by rest. Other common symptoms include muscle pain, joint pain, headaches, unrefreshing sleep, memory problems, and difficulty concentrating.

What causes Chronic Fatigue Syndrome?

The exact cause of CFS is unknown, but it is believed to involve a combination of factors, including viral infections, immune system dysfunction, hormonal imbalances, and genetic predisposition. Psychological factors such as stress may also play a role.

How is Chronic Fatigue Syndrome diagnosed?

There is no specific test for CFS, so diagnosis is based on ruling out other possible causes of the symptoms. Doctors may perform a thorough medical history, physical examination, and various tests to rule out other conditions with similar symptoms.

Is there a cure for Chronic Fatigue Syndrome?

Currently, there is no cure for CFS. Treatment focuses on managing symptoms and improving quality of life. This may include medications to relieve pain and improve sleep, as well as lifestyle changes such as pacing activities and managing stress.

Can exercise help with Chronic Fatigue Syndrome?

While exercise is important for overall health, it can be challenging for people with CFS due to their extreme fatigue and other symptoms.

A carefully tailored exercise program, such as graded exercise therapy, may be beneficial for some individuals, but it should be approached cautiously and under the guidance of a healthcare professional.

Is Chronic Fatigue Syndrome a mental illness?

No, CFS is not a mental illness, although psychological factors such as stress may contribute to its development or exacerbation. CFS is recognized as a physical illness by major medical organizations, including the World Health Organization and the Centers for Disease Control and Prevention.

Can children get Chronic Fatigue Syndrome?

Yes, children and adolescents can develop Chronic Fatigue Syndrome. It may manifest differently in younger individuals compared to adults, with symptoms such as difficulty concentrating, school absences, and reduced participation in activities.

How common is Chronic Fatigue Syndrome?

CFS is estimated to affect between 0.1% and 0.4% of the population, though rates may vary depending on the criteria used for diagnosis and other factors. It can occur in people of all ages, genders, and ethnicities.

What should I do if I think I have Chronic Fatigue Syndrome?

If you are experiencing persistent, unexplained fatigue along with other symptoms of CFS, it’s important to consult with a healthcare professional. They can perform a thorough evaluation to determine the cause of your symptoms and develop an appropriate treatment plan.

Conclusion

Although chronic fatigue syndrome appears to be associated with psychiatric and neurological disorders, other factors such as viral infections, immunity, and hereditary, may also be involved. A better understanding of the etiology of this syndrome using studies that comprise larger cohorts of CSF patients would certainly lead to the development of more efficient therapies that are specific to chronic fatigue syndrome.

References

[1] https://www.cdc.gov/me-cfs/healthcare-providers/presentation-clinical course/epidemiology.html

[2] Afari, N. and Buchwald, D., 2003. Chronic fatigue syndrome: a review. American Journal of Psychiatry, 160(2), pp.221-236.

[3] Lim, E.J., Ahn, Y.C., Jang, E.S., Lee, S.W., Lee, S.H. and Son, C.G., 2020. Systematic review and meta-analysis of the prevalence of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). Journal of translational medicine, 18(1), pp.1-15.

[4] Walsh, C.M., Zainal, N.Z., Middleton, S.J. and Paykel, E.S., 2001. A family history study of chronic fatigue syndrome. Psychiatric genetics, 11(3), pp.123-128.

[5] Buchwald, D., Herrell, R., Ashton, S., Belcourt, M., Schmaling, K., Sullivan, P., Neale, M. and Goldberg, J., 2001. A twin study of chronic fatigue. Psychosomatic medicine, 63(6), pp.936-943.

[6] Tiersky, L.A., Johnson, S.K., Lange, G., Natelson, B.H. and Deluca, J., 1997. Neuropsychology of chronic fatigue syndrome: a critical review. Journal of Clinical and Experimental Neuropsychology, 19(4), pp.560-586.

[7] Parker, A.J.R., Wessely, S. and Cleare, A.J., 2001. The neuroendocrinology of chronic fatigue syndrome and fibromyalgia. Psychological medicine, 31(8), pp.1331-1345.

[8] Barker, E., Fujimura, S.F., Fadem, M.B., Landay, A.L. and Levy, J.A., 1994. Immunologic abnormalities associated with chronic fatigue syndrome. Clinical Infectious Diseases, 18(Supplement_1), pp.S136-S141.

[9] Brenu, E.W., Huth, T.K., Hardcastle, S.L., Fuller, K., Kaur, M., Johnston, S., Ramos, S.B., Staines, D.R. and Marshall-Gradisnik, S.M., 2014. Role of adaptive and innate immune cells in chronic fatigue syndrome/myalgic encephalomyelitis. International immunology, 26(4), pp.233-242.

[10] Mikecz, A.V., Konstantinov, K., Buchwald, D.S., Gerace, L. and Tan, E.M., 1997. High frequency of autoantibodies to insoluble cellular antigens in patients with chronic fatigue syndrome. Arthritis & Rheumatism: Official Journal of the American College of Rheumatology, 40(2), pp.295-305.

[11] Rasa, S., Nora-Krukle, Z., Henning, N., Eliassen, E., Shikova, E., Harrer, T., Scheibenbogen, C., Murovska, M. and Prusty, B.K., 2018. Chronic viral infections in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Journal of translational medicine, 16(1), pp.1-25.

[12] Maksoud, R., Eaton-Fitch, N., Matula, M., Cabanas, H., Staines, D. and Marshall-Gradisnik, S., 2021, May. Systematic Review of Sleep Characteristics in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. In Healthcare (Vol. 9, No. 5, p. 568). Multidisciplinary Digital Publishing Institute.

[13] Stewart, D.E., 1990. Emotional disorders misdiagnosed as physical illness: Environmental hypersensitivity, candidiasis hypersensitivity, and chronic fatigue syndrome. International Journal of Mental Health, 19(3), pp.56-68.

[14] Shorter, E., 2008. From paralysis to fatigue: a history of psychosomatic illness in the modern era. Simon and Schuster.

[15] van der Werf, S.P., Prins, J.B., Vercoulen, J.H., van der Meer, J.W. and Bleijenberg, G., 2000. Identifying physical activity patterns in chronic fatigue syndrome using actigraphic assessment. Journal of psychosomatic research, 49(5), pp.373-379.

[16] Wallman, K.E., Morton, A.R., Goodman, C., Grove, R. and Guilfoyle, A.M., 2004. Randomised controlled trial of graded exercise in chronic fatigue syndrome. Medical Journal of Australia, 180(9), pp.444-448.

The post What Is Chronic Fatigue Syndrome? appeared first on .