Structure and Function: The Endocrine System

Comprehensive vocabulary flashcards covering the major glands, hormones, disorders, and feedback mechanisms of the human endocrine system as described in standard nursing foundations.

Endocrine gland

Ductless glands of internal secretion that secrete hormones directly into the bloodstream.

Exocrine gland

Glands of external secretion that secrete substances into ducts that open onto the body’s external or internal surfaces.

Hormones

Chemical regulators that integrate and coordinate body activities, speeding up or slowing down the activities of organs or systems.

Adenohypophysis

The anterior lobe of the pituitary gland, controlled by the hypothalamus.

Neurohypophysis

The posterior lobe of the pituitary gland, which is an outgrowth of the hypothalamus and embryonically derived from the nervous system.

Hypothalamus

A part of the brain that controls the pituitary gland by releasing hormones that either inhibit or promote the release of hormones from the anterior lobe.

Thyroxine ($T_4$)

A thyroid hormone synthesized from iodine that regulates body metabolism and affects protein synthesis.

Triiodothyronine ($T_3$)

A thyroid hormone synthesized from iodine that is more potent than $T_4$ and regulates the body's metabolic rate.

Calcitonin

A thyroid hormone that lowers serum calcium levels by promoting increased storage of calcium in bones and renal excretion.

$$PTH$$

Parathormone or parathyroid hormone, which regulates calcium and phosphorus levels in the blood and enhances reabsorption of magnesium.

Catecholamines

A group of hormones including epinephrine and norepinephrine secreted by the adrenal medulla that mimic the action of the sympathetic nervous system.

Corticosteroids

Steroid compounds derived from cholesterol secreted by the adrenal cortex, including mineralocorticoids, glucocorticoids, and sex hormones.

Aldosterone

The most important mineralocorticoid, which stimulates reabsorption of sodium and water into the plasma to increase blood volume.

Hydrocortisone ($Cortisol$)

The predominant glucocorticoid that influences metabolic synthesis of glucose and suppresses the inflammatory response.

Islets of Langerhans

Specialized cells in the pancreas that secrete endocrine hormones including alpha, beta, delta, and F cells.

Glucagon

A hormone secreted by alpha cells of the pancreas that raises blood sugar by speeding up glycogenolysis.

Insulin

A hormone secreted by beta cells of the pancreas that lowers blood sugar by enabling cells to use glucose for energy.

Thymosin

A hormone produced by the thymus that stimulates the production of T cells for cellular immunity.

Melatonin

An antioxidant hormone secreted by the pineal gland that participates in maintenance of the sleep–wake cycle.

Prostaglandins

Powerful hormone-like substances with localized effects to the area of production that influence blood pressure, respiration, and reproduction.

Atrial natriuretic factor ($ANf$)

Also called Atrial natriuretic peptide ($ANP$), it is produced by the heart to help maintain fluid homeostasis and lower blood pressure.

Erythropoietin ($EPO$)

A glycoprotein secreted by the kidneys that stimulates red blood cell production.

Renin

An enzyme produced by the kidneys that activates the renin–angiotensin–aldosterone (RAA) mechanism to assist in blood pressure control.

Ghrelin

A hormone secreted by epithelial cells lining the stomach that boosts appetite and slows metabolism.

Leptin

A hormone secreted by fat-storing cells throughout the body that regulates feelings of hunger or fullness.

Acromegaly

A disease caused by hypersecretion of growth hormone after normal growth years, resulting in enlargement of facial, hand, and foot bones.

Gigantism

A condition caused by the hypersecretion of growth hormone during the early formative years of life.

Simple goiter

A painless enlargement of the thyroid gland caused by a low dietary intake of iodine.

Cushing's syndrome

A disorder resulting from the overproduction of glucocorticoids by the adrenal cortex, characterized by a 'moon face' and 'buffalo hump'.

Addison's disease

A condition caused by the hyposecretion of adrenal cortex hormones, resulting in muscle weakness, nausea, and weight loss.

Negative Feedback

A signaling process that monitors hormone levels and halts secretion once the desired effect is achieved to maintain homeostasis.

Positive Feedback

A signaling process where the desired effect intensifies hormone production until a specific event is completed, such as oxytocin during labor.

Target Tissues

Specific remote tissues on which hormones act to perform their regulatory functions.

Glycogenolysis

The process of breaking down stored glycogen into glucose to raise blood sugar levels.

Gluconeogenesis

The formation of glucose from noncarbohydrate sources such as excess amino acids and fatty acids.

Tetany

A clinical sign of severe calcium deficiency characterized by muscle twitching, spasms, and possibly seizures.

$$HCG$$

Human chorionic gonadotropin, a hormone secreted by the placenta that provides the basis for common pregnancy tests.

Androgens

Male sex hormones that produce masculinizing effects, including testosterone and dehydroepiandrosterone ($DHEA$).

Estrogen

A female sex hormone responsible for regulating female sex characteristics, functions, and menstruation.

Progesterone

A primary progestin secreted by the corpus luteum that maintains pregnancy and allows sperm penetration.