Key Terms

acromegaly

condition caused by overproduction of GH in adults

Addison’s disease

disorder caused by the hyposecretion of corticosteroids

adenylate cyclase

an enzyme that catalyzes the conversion of ATP to cyclic AMP

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

adrenocorticotropic hormone (ACTH)

hormone released by the anterior pituitary, which stimulates the adrenal cortex to release corticosteroids during the long-term stress response

aldosterone

steroid hormone produced by the adrenal cortex that stimulates the reabsorption of Na⁺ from extracellular fluids and secretion of K⁺.

alpha cell

endocrine cell of the pancreatic islets that produces the hormone glucagon

amino acid-derived hormone

hormone derived from amino acids

androgen

male sex hormone such as testosterone

anterior pituitary

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

antidiuretic hormone (ADH)

hormone produced by the hypothalamus and released by the posterior pituitary that increases water reabsorption by the kidneys

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

calcitonin

hormone produced by the parafollicular cells of the thyroid gland that functions to lower blood Ca²⁺ levels and promote bone growth

colloid

fluid inside the thyroid gland that contains the glycoprotein thyroglobulin

corticosteroid

hormone released by the adrenal cortex in response to long-term stress

cortisol

glucocorticoid produced in response to stress

Cushing’s disease

disorder caused by the hypersecretion of glucocorticoids

diabetes insipidus

disorder caused by underproduction of ADH

diabetes mellitus

disorder caused by low levels of insulin activity

diabetogenic effect

effect of GH that causes blood glucose levels to rise similar to diabetes mellitus

down-regulation

a decrease in the number of hormone receptors in response to increased hormone levels

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

epinephrine

hormone released by the adrenal medulla in response to a short term stress

erythropoietin (EPO)

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

estrogens

- a group of steroid hormones, including estradiol and several others, that are produced by the ovaries and elicit secondary sex characteristics in females as well as control the maturation of the ova

first messenger

the hormone that binds to a plasma membrane hormone receptor to trigger a signal transduction pathway

follicle-stimulating hormone (FSH)

hormone produced by the anterior pituitary that stimulates gamete production

G-protein

a membrane protein activated by the hormone first messenger to activate formation of cyclic AMP

gigantism

condition caused by overproduction of GH in children

glucagon

hormone produced by the alpha cells of the pancreas in response to low blood sugar; functions to raise blood sugar levels

glucocorticoid

corticosteroid that affects glucose metabolism

gluconeogenesis

synthesis of glucose from amino acids

glucose-sparing effect

effect of GH that causes tissues to use fatty acids instead of glucose as an energy source

glycogenolysis

breakdown of glycogen into glucose

goiter

enlargement of the thyroid gland caused by insufficient dietary iodine levels

gonadotropin

hormone that regulates the gonads, including FSH and LH

growth hormone (GH)

hormone produced by the anterior pituitary that promotes protein synthesis and body growth

growth hormone-inhibiting hormone (GHIH)

hormone produced by the hypothalamus that inhibits growth hormone production, also called somatostatin

growth hormone-releasing hormone (GHRH)

hormone released by the hypothalamus that triggers the release of GH

hormonal stimuli

release of a hormone in response to another hormone

hormone receptor

the cellular protein that binds to a hormone

humoral stimuli

control of hormone release in response to changes in extracellular fluids such as blood or the ion concentration in the blood

hyperglycemia

high blood sugar level

hyperthyroidism

overactivity of the thyroid gland

hypoglycemia

low blood sugar level

hypophyseal portal system

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

hypothyroidism

underactivity of the thyroid gland

insulin

hormone produced by the beta cells of the pancreas in response to high blood glucose levels; functions to lower blood glucose levels

insulin-like growth factor (IGF)

growth-promoting protein produced by the liver

intracellular hormone receptor

a hormone receptor in the cytoplasm or nucleus of a cell

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

lipid-derived hormone

hormone derived mostly from cholesterol

mineralocorticoid

corticosteroid that affects ion and water balance

neural stimuli

stimulation of endocrine glands by the nervous system

norepinephrine

hormone released by the adrenal medulla in response to a short-term stress hormone production by the gonads

osmoreceptor

receptor in the hypothalamus that monitors the concentration of electrolytes in the blood

oxytocin

hormone released by the posterior pituitary to stimulate uterine contractions during childbirth and milk let-down in the mammary glands

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

parathyroid hormone (PTH)

hormone produced by the parathyroid glands in response to low blood Ca²⁺ levels; functions to raise blood Ca²⁺ levels

peptide hormone

hormone composed of a polypeptide chain

phosphodiesterase (PDE)

enzyme that deactivates cAMP, stopping hormone activity

pituitary dwarfism

condition caused by underproduction of GH in children

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

plasma membrane hormone receptor

a hormone receptor on the surface of the plasma membrane of a cell

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

prolactin (PRL)

hormone produced by the anterior pituitary that stimulates milk production

prolactin-inhibiting hormone

hormone produced by the hypothalamus that inhibits the release of prolactin

prolactin-releasing hormone

hormone produced by the hypothalamus that stimulates the release of prolactin

renin

enzyme produced by the juxtaglomerular apparatus of the kidneys that reacts with angiotensinogen to cause the release of aldosterone

thymus

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

thyroglobulin

glycoprotein found in the thyroid that is converted into thyroid hormone

thyroid gland

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

thyroid-stimulating hormone (TSH)

hormone produced by the anterior pituitary that controls the release of T₃ and T₄ from the thyroid gland

thyroxine (tetraiodothyronine, T₄)

thyroid hormone containing 4 iodines that controls the basal metabolic rate

triiodothyronine (T₃)

thyroid hormone containing 3 iodines that controls the basal metabolic rate

up-regulation

an increase in the number of hormone receptors in response to increased hormone levels