Endocrine system terms

acromegaly disorder in adults caused when abnormally high levels of GH trigger growth of bones in the face, hands, and feet

adenylyl cyclase membrane-bound enzyme that converts ATP to cyclic AMP, creating cAMP, as a result of G-protein activation

adrenal cortex outer region of the adrenal glands consisting of multiple layers of epithelial cells and capillary networks that produces mineralocorticoids and glucocorticoids

adrenal glands endocrine glands located at the top of each kidney that are important for the regulation of the stress response, blood pressure and blood volume, water homeostasis, and electrolyte levels

adrenal medulla inner layer of the adrenal glands that plays an important role in the stress response by producing epinephrine and norepinephrine

adrenocorticotropic hormone (ACTH) anterior pituitary hormone that stimulates the adrenal cortex to secrete corticosteroid hormones (also called corticotropin)

angiotensin-converting enzyme the enzyme that converts angiotensin I to angiotensin II

antidiuretic hormone (ADH) hypothalamic hormone that is stored by the posterior pituitary and that signals the kidneys to reabsorb water

alarm reaction the short-term stress, or the fight-or-flight response, of stage one of the general adaptation syndrome mediated by the hormones epinephrine and norepinephrine

aldosterone hormone produced and secreted by the adrenal cortex that stimulates sodium and fluid retention and increases blood volume and blood pressure

alpha cell pancreatic islet cell type that produces the hormone glucagon

autocrine chemical signal that elicits a response in the same cell that secreted it

beta cell pancreatic islet cell type that produces the hormone insulin

calcitonin peptide hormone produced and secreted by the parafollicular cells (C cells) of the thyroid gland that functions to decrease blood calcium levels

chromaffin neuroendocrine cells of the adrenal medulla

colloid viscous fluid in the central cavity of thyroid follicles, containing the glycoprotein thyroglobulin

cortisol glucocorticoid important in gluconeogenesis, the catabolism of glycogen, and downregulation of the immune system

cyclic adenosine monophosphate (cAMP) second messenger that, in response to adenylyl cyclase activation, triggers a phosphorylation cascade

delta cell minor cell type in the pancreas that secretes the hormone somatostatin

diabetes mellitus condition caused by destruction or dysfunction of the beta cells of the pancreas or cellular resistance to insulin that results in abnormally high blood glucose levels

diacylglycerol (DAG) molecule that, like cAMP, activates protein kinases, thereby initiating a phosphorylation cascade

downregulation decrease in the number of hormone receptors, typically in response to chronically excessive levels of a hormone

endocrine gland tissue or organ that secretes hormones into the blood and lymph without ducts such that they may be transported to organs distant from the site of secretion

endocrine system cells, tissues, and organs that secrete hormones as a primary or secondary function and play an integral role in normal bodily processes

epinephrine primary and most potent catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called adrenaline

estrogens class of predominantly female sex hormones important for the development and growth of the female reproductive tract, secondary sex characteristics, the female reproductive cycle, and the maintenance of pregnancy

exocrine system cells, tissues, and organs that secrete substances directly to target tissues via glandular ducts

first messenger hormone that binds to a cell membrane hormone receptor and triggers activation of a second messenger system

follicle-stimulating hormone (FSH) anterior pituitary hormone that stimulates the production and maturation of sex cells

G protein protein associated with a cell membrane hormone receptor that initiates the next step in a second messenger system upon activation by hormone–receptor binding

general adaptation syndrome (GAS) the human body’s three-stage response pattern to short- and long-term stress

gigantism disorder in children caused when abnormally high levels of GH prompt excessive growth

glucagon pancreatic hormone that stimulates the catabolism of glycogen to glucose, thereby increasing blood glucose levels

glucocorticoids hormones produced by the zona fasciculata of the adrenal cortex that influence glucose metabolism

goiter enlargement of the thyroid gland either as a result of iodine deficiency or hyperthyroidism

gonadotropins hormones that regulate the function of the gonads

growth hormone (GH) anterior pituitary hormone that promotes tissue building and influences nutrient metabolism (also called somatotropin)

hormone secretion of an endocrine organ that travels via the bloodstream or lymphatics to induce a response in target cells or tissues in another part of the body

hormone receptor protein within a cell or on the cell membrane that binds a hormone, initiating the target cell response

hyperglycemia abnormally high blood glucose levels

hyperparathyroidism disorder caused by overproduction of PTH that results in abnormally elevated blood calcium

hyperthyroidism clinically abnormal, elevated level of thyroid hormone in the blood; characterized by an increased metabolic rate, excess body heat, sweating, diarrhea, weight loss, and increased heart rate

hypoparathyroidism disorder caused by underproduction of PTH that results in abnormally low blood calcium

hypophyseal portal system network of blood vessels that enables hypothalamic hormones to travel into the anterior lobe of the pituitary without entering the systemic circulation

hypothalamus region of the diencephalon inferior to the thalamus that functions in neural and endocrine signaling

hypothyroidism clinically abnormal, low level of thyroid hormone in the blood; characterized by low metabolic rate, weight gain, cold extremities, constipation, and reduced mental activity

infundibulum stalk containing vasculature and neural tissue that connects the pituitary gland to the hypothalamus (also called the pituitary stalk)

inhibin hormone secreted by the male and female gonads that inhibits FSH production by the anterior pituitary

inositol triphosphate (IP₃) molecule that initiates the release of calcium ions from intracellular stores

insulin pancreatic hormone that enhances the cellular uptake and utilization of glucose, thereby decreasing blood glucose levels

insulin-like growth factors (IGF) protein that enhances cellular proliferation, inhibits apoptosis, and stimulates the cellular uptake of amino acids for protein synthesis

luteinizing hormone (LH) anterior pituitary hormone that triggers ovulation and the production of ovarian hormones in females, and the production of testosterone in males

melatonin amino acid–derived hormone that is secreted in response to low light and causes drowsiness

mineralocorticoids hormones produced by the zona glomerulosa cells of the adrenal cortex that influence fluid and electrolyte balance

neonatal hypothyroidism condition characterized by cognitive deficits, short stature, and other signs and symptoms in people born to women who were iodine-deficient during pregnancy

norepinephrine secondary catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called noradrenaline

osmoreceptor hypothalamic sensory receptor that is stimulated by changes in solute concentration (osmotic pressure) in the blood

oxytocin hypothalamic hormone stored in the posterior pituitary gland and important in stimulating uterine contractions in labor, milk ejection during breastfeeding, and feelings of attachment (also produced in males)

pancreas organ with both exocrine and endocrine functions located posterior to the stomach that is important for digestion and the regulation of blood glucose

pancreatic islets specialized clusters of pancreatic cells that have endocrine functions; also called islets of Langerhans

parathyroid glands small, round glands embedded in the posterior thyroid gland that produce parathyroid hormone (PTH)

parathyroid hormone (PTH) peptide hormone produced and secreted by the parathyroid glands in response to low blood calcium levels

phosphorylation cascade signaling event in which multiple protein kinases phosphorylate the next protein substrate by transferring a phosphate group from ATP to the protein

pineal gland endocrine gland that secretes melatonin, which is important in regulating the sleep-wake cycle

pinealocyte cell of the pineal gland that produces and secretes the hormone melatonin

pituitary dwarfism disorder in children caused when abnormally low levels of GH result in growth retardation

pituitary gland bean-sized organ suspended from the hypothalamus that produces, stores, and secretes hormones in response to hypothalamic stimulation (also called hypophysis)

PP cell minor cell type in the pancreas that secretes the hormone pancreatic polypeptide

progesterone predominantly female sex hormone important in regulating the female reproductive cycle and the maintenance of pregnancy

prolactin (PRL) anterior pituitary hormone that promotes development of the mammary glands and the production of breast milk

second messenger molecule that initiates a signaling cascade in response to hormone binding on a cell membrane receptor and activation of a G protein

stage of exhaustion stage three of the general adaptation syndrome; the body’s long-term response to stress mediated by the hormones of the adrenal cortex

stage of resistance stage two of the general adaptation syndrome; the body’s continued response to stress after stage one diminishes

testosterone steroid hormone secreted by the male testes and important in the maturation of sperm cells, growth and development of the male reproductive system, and the development of male secondary sex characteristics

thyroid-stimulating hormone (TSH) anterior pituitary hormone that triggers secretion of thyroid hormones by the thyroid gland (also called thyrotropin)

thyroxine (also, tetraiodothyronine, T₄) amino acid–derived thyroid hormone that is more abundant but less potent than T₃ and often converted to T₃ by target cells

triiodothyronine (also, T₃) amino acid–derived thyroid hormone that is less abundant but more potent than T₄

upregulation increase in the number of hormone receptors, typically in response to chronically reduced levels of a hormone

zona fasciculata intermediate region of the adrenal cortex that produce hormones called glucocorticoids

zona glomerulosa most superficial region of the adrenal cortex, which produces the hormones collectively referred to as mineralocorticoids

zona reticularis deepest region of the adrenal cortex, which produces the steroid sex hormones called androgens