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Endocrine glands are ductless organs that secret hormones either into the bloodstream or the fluid around cells.
Hormones are substances secreted by cells that act to regulate the activity of other cells in the body.

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◦ control the initial release of many hormones
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◦ The thyroid gland is located near the larynx and helps maintain a normal heart rate, blood pressure, and body temperature

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◦ Humans have an adrenal gland located above each kidney
◦ The adrenal medulla secretes the hormones that stimulate a “flightor-fight” response to a stress.
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◦ are the gameteproducing organs that also produce a group of steroid sex hormones.

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Pancreas
◦ Secretes insulin and glucagon to regulate blood sugar
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Thymus Gland
◦ The thymus gland is located beneath the sternum and plays a role in the development of the immune system by secreting thymosin.
◦ This amino acid-based hormone stimulates formation of T cells.

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◦ The pineal gland is located near the base of the brain and helps regulate sleep patterns by secreting melatonin.
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◦ These glands secrete the parathyroid hormone, which stimulates the transfer of calcium ions from the bones to the blood.