The endocrine system is an integrated system of organs which involve the release of extracellular signaling molecules known as hormones. The endocrine system is instrumental in regulating metabolism, growth and development, tissue function, and plays a part also in mood.[1] The field of medicine that deals with disorders of endocrine glands is endocrinology, a branch of the wider field of internal medicine.
Signal transduction of some hormones with steroid structure involves nuclear hormone receptor proteins that are a class of ligand activated proteins that, when bound to specific sequences of DNA serve as on-off switches for transcription within the cell nucleus. These switches control the development and differentiation of skin, bone and behavioral centers in the brain, as well as the continual regulation of reproductive tissues.
The nervous system sends electrical messages to control and coordinate the body. The endocrine system has a similar job, but uses chemicals to "communicate". These chemicals are known as hormones. A hormone is a specific messenger molecule synthesized and secreted by a group of specialized cells called an endocrine gland. These glands are ductless, which means that their secretions (hormones) are released directly into the bloodstream and travel to elsewhere in the body to target organs, upon which they act. Note that this is in contrast to our digestive glands, which have ducts for releasing the digestive enzymes.
Diseases of the endocrine system are common, including diseases such as diabetes mellitus, thyroid disease and obesity. Endocrine disease is characterised by dysregulated hormone release (a productive Pituitary adenoma), inappropriate response to signalling (Hypothyroidism), lack or destruction of a gland (Diabetes mellitus type 1, diminished erythropoiesis in Chronic renal failure) or structural enlargement in a critical site such as the neck (Toxic multinodular goitre). Hypofunction of endocrine glands can occur as result of loss of reserve, hyposecretion, agenesis, atrophy or active destruction. Hyperfunction can occur as result of hypersecretion, loss of suppression, hyperplastic or neoplastic change, or hyperstimulation.
Endocrinopathies are classified as primary, secondary, or tertiary. Primary endocrine , or inhibits the action of downstream glands. Tertiary endocrine disease is associated with dysfunction of the hypothalamus and its releasing hormones.
Cancer can occur in endocrine glands, such as the thyroid, and hormones have been implicated in signalling distant tissues to proliferate, for example the Estrogen receptor has been shown to be involved in certain breast cancers. Endocrine, Paracrine and autocrine signalling have all been implicated in proliferation, one of the required steps of oncogenesis.
Parathyroid glands secretes a parathyroid hormone, which affects calcium levels in the blood. The sole purpose of the parathyroid glands are to regulate the calcium level in our bodies within a very narrow range so that the nervous and muscular systems can function properly.
Hypothalamus is a region of the brain located below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate certain metabolic processes and other autonomic activities. The hypothalamus links the nervous system to the endocrine system by producing releasing hormones.
Endocrine disorders include some of the most common medical conditions such as diabetes, high cholesterol and thyroid problems. These disorders involve the system of glands and hormones that help regulate our metabolism, growth and reproduction. Less common endocrine disorders include diseases of the pituitary, parathyroid and adrenal glands. Common diseases such as osteoporosis and reproductive disorders are managed jointly by endocrinologists and other specialists. Treating these disorders usually involves the help of a team of health care professionals, including physicians, trainees and dietitian and nurse educators. |
