Overview of the Endocrine System 

The endocrine system is made up of several glands and tissues, which are made of specialized cells that synthesize, store, and secrete hormones. The endocrine system controls a range of processes in the body, including maintaining homeostasis (Ashwell, 2022). 

Ashwell, E. (2022). The endocrine system and associated disorders. British Journal of Nursing, 31(6), 316–320. https://doi.org/10.12968/bjon.2022.31.6.316 

Features of the Endocrine System 

• Communication Method

  • Endocrine glands secrete hormones; hormones are transported within the blood target cells throughout body 

• Target of Stimulation 

  • Any cell in the body with a receptor for the hormone

• Response Time

  • Relatively slow reaction time: Seconds to minutes to hours

• Range of Effect

  • Typically has widespread effects throughout the body

• Duration of Response

  • Long-lasting: Minutes to days to weeks; may continue after stimulus is removed

The endocrine system consists of glands widely separated from each other with no direct anatomical links.

It also consists of the number of cells, tissue, and organs that secrete hormones. Endocrine glands are ductless glands as the hormones directly secreted and diffuse into the bloodstream.

The endocrine system consists of a number of distinct glands and some tissues in other organs. Although the hypothalamus is classified as a part of the brain and not as an endocrine gland it controls the pituitary gland and has an indirect effect on many others. The endocrine glands are:

• 1 Pituitary gland- Master gland of the body, it has two lobes, present at the base of the brain in the form of a protrusion, and it secretes 9 different major hormones

• 1 Thyroid gland- One of the largest glands of the body, found in the neck below the thyroid cartilage, mainly controls body metabolism, and it secretes 3 different hormones

• 4 Parathyroid glands- Located behind the thyroid gland, produce parathormone

• 2 Adrenal (suprarenal) glands- Found attached to the kidneys, consists of two parts; Cortex and Medulla, the Adrenal cortex produces 3 different hormones, and the Adrenal medulla produces 4 different hormones

• The pancreatic islets- Primarily an organ of the digestive system, produces 4 different hormones including Insulin and Glucagon

• 1 Pineal gland

• 1 Thymus gland

• 2 Ovaries in the female

• 2 Testes in the male

Endocrine System Vocabulary:

Endocrine Organ: a single organ that is entirely endocrine in function. Endocrine organs include the pituitary gland, pineal gland, thyroid gland, parathyroid glands, and adrenal glands. 

Endocrine system: composed of endocrine glands located throughout the body.

Endocrine glands: typically composed of a connective tissue framework, which houses and supports epithelial tissue that produces and releases hormones from their secretory cells. 

Target Cells: Cells that have specific receptors for a hormone.

Prostaglandin: local hormone derived from a fatty acid of the plasma membrane

Half-Life: Time required to reduce a substance by one-half of its original quantity. 

Synergistic: Hormones work together to produce greater effect 

Permissive: First hormone allows action of second hormone

Antagonistic: One hormone causes the opposite effect of another hormone