Endocrine System Flashcards

Vocabulary flashcards for the endocrine system lecture.

Endocrine System

Coordinates body systems using hormones produced by endocrine structures.

Parathyroid Glands

Small, round masses attached to the posterior surface of the thyroid gland's lateral lobes; usually two on each lobe (superior and inferior).

Parathyroid Hormone (PTH)

Stimulates osteoclastic activity in bones, Ca2+ reabsorption in kidneys, and (indirectly) Ca2+ absorption from the GI tract, made by chief cells.

Calcitonin (Thyrocalcitonin)

Made by parafollicular (C-cells) of the thyroid gland; lowers blood calcium levels by causing more calcium to be deposited in bone.

Adrenal Glands

Two glands, one superior to each kidney, consisting of the adrenal cortex and adrenal medulla.

Adrenal Cortex

The peripherally located region of the adrenal gland that secretes steroid hormones in three zones: glomerulosa, fasciculata, and reticularis.

Mineralocorticoids

Regulate Na+ and K+ concentrations in the blood, affecting blood volume and pressure; aldosterone is the major hormone.

Glucocorticoids

Influence glucose metabolism and the ability to resist stress; cortisol is the major hormone in this group.

Weak Androgens

Masculinizing sex hormones produced by the adrenal cortex. They have little effect in men, but play an important role in promoting libido in women.

Aldosterone

Important part of the renin-angiotensin-aldosterone system (RAAS); regulates Na+ and K+ levels.

Renin-Angiotensin-Aldosterone System (RAAS)

A system that regulates blood pressure and volume, involving renin, angiotensin, and aldosterone.

Glucocorticoids (mainly cortisol)

Regulate metabolism; promote breakdown of proteins and fats to form glucose (gluconeogenesis) and reduce inflammatory effects.

Adrenal Medulla

The inner region of the adrenal gland; a modified sympathetic ganglion of the ANS that secretes catecholamines, epinephrine, and norepinephrine.

Catecholamines

Includes epinephrine (80%) and norepinephrine (20%); enhances and prolongs the sympathetic response.

General Adaptation Syndrome (GAS)

The body's response to emotional or physical threats, also known as the stress response; includes alarm reaction, resistance reaction, and exhaustion.

Alarm Reaction

The short-lived fight-or-flight response, initiated by the hypothalamus and mediated by the sympathetic division of the ANS.

Resistance Reaction

A longer-lasting response initiated by hypothalamic releasing hormones; release of high levels of cortisol and thyroid hormones.

Exhaustion

Occurs when the body's reserves are depleted and cannot sustain the resistance stage; prolonged exposure to high levels of cortisol and other hormones.

Pancreas

An organ is both an endocrine and an exocrine gland, located posterior and inferior to the stomach.

Pancreatic Islets (Islets of Langerhans)

Endocrine tissue clusters in the pancreas, containing alpha, beta, delta, and F cells.

Alpha Cells

Secrete glucagon in the pancreatic islets.

Beta Cells

Secrete insulin in the pancreatic islets.

Glucagon

Increases blood glucose levels by acting on hepatocytes to convert glycogen and other nutrients to glucose.

Insulin

Decreases blood glucose levels by promoting hepatocytes to convert glucose to glycogen and facilitating the diffusion of glucose into cells.

Somatostatin

A paracrine hormone that inhibits both insulin and glucagon secretion; also inhibits the secretion of hGH.

Ovaries

Paired oval bodies located in the female pelvic cavity that produce estrogen and progesterone.

Estrogens

Regulate the menstrual cycle, maintain pregnancy, and prepare the mammary glands for lactation.

Progesterone

Prepares the uterine lining for implantation of a fertilized ovum.

Testes

Oval glands that lie in the male scrotum and produce testosterone.

Testosterone

An androgen needed for the production of sperm and maintenance of male secondary sex characteristics.

Pineal Gland

Small endocrine gland attached to the roof of the third ventricle; secretes melatonin.

Melatonin

Contributes to maintaining the biological clock (seasonal and daily cycles).

Thymus Gland

Secretes thymosin, which promotes the proliferation and maturation of T cells.

T Cells

A type of white blood cell (lymphocyte) that destroys microorganisms and foreign substances through direct cellular contact.