Endocrine System Terminology

Endocrine Gland

Ductless gland that empties it’s hormonal product directly into the blood

Exocrine Gland

Gland that has ducts through which their secretions are carried to a particular site.

Hormone

Steroidal or amino acid-based molecules released to the blood that act as a chemical messenger to regulate specific body functions

Amino Acid/ Peptide Hormone

Organic compound containing nitrogen, carbon, hydrogen, and oxygen; building block of protein

Steroid hormone

hormone made from cholesterol

Prostaglandin

a lipid-based chemical messenger synthesized by most tissue cells; acts locally as a paracrine

Target cells

any cell that a hormone can act on because it has the right receptor

Second Messengers

Intracellular molecule generated by the binding of a chemical to a receptor protein; mediates intracellular responses to the chemical messenger

Cyclic AMP

Intracellular second messenger that mediates the effects of the first (extracellular) messenger (hormone); formed from ATP by a plasma membrane enzyme

Protein kinases

enzyme that phosphorylates a protein, resulting in activation or inactivation of the protein

Direct gene activation

regulation of gene transcription by a hormone-receptor complex that binds directly to DNA

Humoral stimuli

changes in the levels of substances in the blood that directly trigger hormone release from an endocrine gland

Neural Stimuli

nerve impulses that trigger the release of hormones from an endocrine gland

Hormonal stimuli

when one hormone triggers the release of another hormone from an endocrine gland e4

Releasing hormones

hormones produced by the hypothalamus that stimulates the anterior pituitary to secrete specific horones

inhibiting hormones

hormones produced by the hypothalamus that suppress the secretion of specific hormones from the anterior pituitary

pituitary gland or hypophysis

neuroendocrine gland located beneath the brain that serves a variety of functions including regulation of gonads, thyroid, adrenal cortex, lactation and water balance

posterior pituitary or neurohypohysis

neural part of pituitary gland; part of the neurohypophysis

anterior pituitary or adenohypophysis

the glandular part of the pituitary gland

growth hormone

hormone that stimulates growth in general; produced in the anterior pituitary; also called somatotropin

pituitary dwarfism

condition caused by insufficient secretion of GH from the anterior pituitary during childhood, resulting in abnormally short stature with normal body proportions

gigantism

disorder caused by excess secretion of GH during childhood, leading to abnormally excessive height

acromegaly

disorder caused by excess GH secretion in adulthood, leading to enlargement of bones and soft tissue

thyroid-stimulating hormone (TSH)

anterior pituitary hormone that regulates secretion of thyroid hormones

adrenocoticotropic hormone (ACTH)

anterior pituitary hormone that influences the activity of the adrenal cortex

gonadotropins

gonad-stimulating hormones produced by the anterior pituitary

follicle-stimulating hormone (FSH)

Hormone produced by the anterior pituitary that stimulates ovarian follicle production in females and sperm production in males

luteinizing hormone (LH)

anterior pituitary hormones that aids maturation of cells in the ovary and triggers ovulation in females. in males, causes the interstitial endocrine cells of the testis to produce testosterone

prolactin (PRL)

anterior pituitary hormone that stimulates the breasts to produce milk

oxytocin

hormone synthesized in the hypothalamus and secreted by the posterior pituitary; stimulates contraction of the uterus during childbirth and the ejection of milk during nursing

antidiuretic hormone (ADH)

hormone produced by the hypothalamus and released by the posterior pituitary; stimulates the kidneys to reabsorb more water, reducing urine volume

diabetes insipidus

disease characterized by passage of a large quantity of dilute urine plus intense thirst and dehydration caused by inadequate release of antidiuretic hormone

thyroid gland

one of the largest of the body’s endocrine glands; straddles the anterior trachea

thyroid follicles

structural and function units of thyroid gland that produce, store and secrete thyroid hormones

colloid

a mixture in which the solute particles do not settle out readily. substance in the thyroid gland containing thyroglobulin protein

thyroxine T4

iodine-containing hormone secreted by the thyroid gland; accelerates cellular metabolic rate in most body tissues

triiodothyronine T3

thyroid hormone, secretion and function similar to those of thyroxine

endemic goiter

enlargement of the thyroid bland, due to insufficient iodine in the diet

myxedema

severe hypothyroidism

cretinism

condition caused by severe deficiency of thyroid hormones during infancy or early childhood, leading to stunted physical growth and mental retardation

grave’s disease

autoimmune disorder in which the thyroid gland is directly stimulated by antibodies; causes markedly increased secretion of thyroid hormone

calcitonin

hormone produced by the thyroid gland’s parafollicular cells that helps lower blood calcium levels

parafollicular or C cells

specialized cells in the thyroid that produce the hormone calcitonin

parathyroid glands

small endocrine glands located on the posterior aspect of the thyroid gland

parathyroid hormone (PTH)

hormone released by the parathyroid glands that regulates blood calcium level

adrenal glands

hormone-producing glands located superior to the kidneys; each consists of medulla and cortex areas

adrenal medulla

inner part of adrenal gland, functions as a neuroendocrine organ, producing catecholamine hormones

adrenal cortex

outer layer of adrenal gland that produces steroid hormones essential for metabolism, salt balance and stress response

corticosteroids

steroid hormones released by the adrenal cortex

mineralocorticoids

steroid hormones produced by the adrenal cortex that regulate the balance of water and electrolytes in the body

aldosterone

hormone produced by the adrenal cortex that regulates Na+ reabsorption and K+ secretion by the kidneys

addison’s disease

disorder caused by chronic deficiency of adrenal cortex hormones- cortisol and aldosterone, leading to a range of metabolic disturbances

glucocoritcoids

adrenal cortex hormones that increase blood glucose levels and aid the body in resisting long term stressors

epinephrine

chief hormone produced by the adrenal medulla. also called adrenaline.

norepinephrine

a catecholamine neurotransmitter and adrenal medullary hormone, associated with sympathetic nervous system activation

pancreas

gland located behind the stomach, between the spleen and duodenum; produces both endocrine and exocrine secretions

acinar cells

exocrine cells of pancreas that produce digestive enzymes which are secreted into the small intestine

pancreatic islets (islets of Langerhans)

clusters of endocrine cells in the pancreas that produce hormones regulating blood glucose and metabolism

alpha cells

endocrine cells in the pancreatic islets that secrete glucagon

beta cells

endocrine cells in the pancreatic islets that secrete insulin

glucagon

hormone formed by alpha cells of pancreatic islets; raises the glucose level of blood

insulin

a hormone that enhances the carrier-mediated diffusion of glucose into tissue cells, thus lowering blood glucose levels

diabetes mellitus

disease caused by deficient insulin release or by insulin resistance, leading to inability of the body cells to use carbohydates

gonads

primary reproductive organ; the testis of the male or the ovary of the female

estrogen

hormones that stimulate female secondary sex characteristics

progesterone

hormone partly responsible for preparing the uterus for the fertilized ovum

testosterone

male sex hormone produced by the testes; during puberty promotes virilization, and is necessary for formal sperm production

pineal gland

hormone-secreting part of the diencephalon of the brain thought to be involved in setting the biological clock and influencing reproductive function

melatonin

hormone secreted by the pineal gland that helps regulate circadian rythms

thymus gland

endocrine gland located in the chest that places a crucial role in the development of the immune system