The endocrine glands

What is a gland?

Endocrine glands create (synthesize) and release (secrete) hormones directly into the blood stream. Hormones are the bodies chemical messengers that instruct glands and cells to perform necessary functions. For instance when the eye senses light, it informs the pineal gland which will stop producing melatonin, a chemical responsible for regulating sleep cycles. When the lights go out it releases melatonin to help us go to sleep.

The endocrine glands operate by instructions sent via the nervous system, the hypothalamus is the direct link to the nervous system, and paired with the pituitary gland they instruct the entire endocrine system. For instance the hypothalamus secretes GHRH a hormone, that tells the pituitary to release GH the growth hormone in our bodies that assists in growth and cell reproduction. The glands themselves will also test blood content and pressure in example, when blood pressure is low, the kidneys will secrete Renin, which stimulates blood vessels to constrict, causing blood pressure to rise.

The glands will create (synthesize) hormones from base molecular ingredients like amino acids, proteins, cholesterol, peptides, and fatty acids provided through the blood via the digestive system. The endocrine glands will then store or release the hormones as needed.

It is important to mention that most cells in the body are capable of creating and releasing hormones, but in general cells only affect themselves, or neighboring cells. Though these cells are apart of the endocrine system, the endocrine glands are considered to do the majority of the hormone work. The major glands that make up the endocrine system are the hypothalamus, pituitary, pineal, thyroid, liver, pancreas, kidneys, adrenals, ovaries, and testes.