Summarizing Endocrine Glands

Summary

The pituitary gland is located at the base of the brain and is attached to the hypothalamus by the infundibulum. The anterior pituitary receives products from the hypothalamus by the hypophyseal portal system and produces six hormones. The posterior pituitary is an extension of the brain and releases hormones (antidiuretic hormone and oxytocin) produced by the hypothalamus.

The thyroid gland is located in the neck and is composed of two lobes connected by the isthmus. The thyroid is made up of follicle cells that produce the hormones thyroxine and triiodothyronine. Parafollicular cells of the thyroid produce calcitonin. The parathyroid glands lie on the posterior surface of the thyroid gland and produce parathyroid hormone.

The adrenal glands are located on top of the kidneys and consist of the renal cortex and renal medulla. The adrenal cortex is the outer part of the adrenal gland and produces the corticosteroids, glucocorticoids, and mineralocorticoids. The adrenal medulla is the inner part of the adrenal gland and produces the catecholamines epinephrine and norepinephrine.

The pancreas lies in the abdomen between the stomach and the small intestine. Clusters of endocrine cells in the pancreas form the islets of Langerhans, which are composed of alpha cells that release glucagon and beta cells that release insulin.

Some organs possess endocrine activity as a secondary function but have another primary function. The heart produces the hormone atrial natriuretic peptide, which functions to reduce blood volume, pressure, and Na⁺ concentration. The gastrointestinal tract produces various hormones that aid in digestion. The kidneys produce renin, calcitriol, and erythropoietin. Adipose tissue produces leptin, which promotes satiety signals in the brain.

Glossary

adrenal cortex

outer portion of adrenal glands that produces corticosteroids

adrenal gland

endocrine glands associated with the kidneys

adrenal medulla

inner portion of adrenal glands that produces epinephrine and norepinephrine

alpha cell

endocrine cell of the pancreatic islets that produces the hormone glucagon

anterior pituitary

portion of the pituitary gland that produces six hormones; also called adenohypophysis

atrial natriuretic peptide (ANP)

hormone produced by the heart to reduce blood volume, pressure, and Na⁺ concentration

beta cell

endocrine cell of the pancreatic islets that produces the hormone insulin

colloid

fluid inside the thyroid gland that contains the glycoprotein thyroglobulin

endocrine gland

gland that secretes hormones into the surrounding interstitial fluid, which then diffuse into blood and are carried to various organs and tissues within the body

erythropoietin (EPO)

hormone produced by the kidneys to stimulate red blood cell production in the bone marrow

hypophyseal portal system

system of blood vessels that carries hormones from the hypothalamus to the anterior pituitary

islets of Langerhans (pancreatic islets)

endocrine cells of the pancreas

isthmus

tissue mass that connects the two lobes of the thyroid gland

leptin

hormone produced by adipose tissue that promotes feelings of satiety and reduces hunger

pancreas

organ located between the stomach and the small intestine that contains exocrine and endocrine cells

parafollicular cell

thyroid cell that produces the hormone calcitonin

parathyroid gland

gland located on the surface of the thyroid that produces parathyroid hormone

pituitary gland

endocrine gland located at the base of the brain composed of an anterior and posterior region; also called hypophysis

pituitary stalk

(also, infundibulum) stalk that connects the pituitary gland to the hypothalamus

posterior pituitary

extension of the brain that releases hormones produced by the hypothalamus; along with the infundibulum, it is also referred to as the neurohypophysis

thymus

gland located behind the sternum that produces thymosin hormones that contribute to the development of the immune system

thyroid gland

endocrine gland located in the neck that produces thyroid hormones thyroxine and triiodothyronine