Endocrine System Vocabulary Flashcards

Vocabulary flashcards covering the primary glands, neurohormones, cell types, and chemical signaling mechanisms of the endocrine system based on the lecture transcript.

Hormones

Chemical messengers synthesized and secreted by endocrine organs into the blood to regulate the functions of other target cells.

Endocrine Signaling

A signaling pathway where hormones are secreted into the bloodstream by endocrine cells to travel and interact with distant target cells.

Paracrine Signaling

A signaling pathway where chemicals are secreted by cells into extracellular space to affect nearby but different types of cells.

Autocrine Signaling

A signaling pathway where chemicals are secreted by cells into interstitial fluid to elicit effects from the same cell or cell type.

Exocrine Glands

Glands that secrete their products into ducts that lead to body surfaces or cavities.

Neuroendocrine Organs

Secondary endocrine organs composed of nervous tissue that secrete neurohormones, including the hypothalamus, pineal gland, and adrenal medulla.

Amino-Acid Hormones

Hormones consisting of one or more amino acids, ranging from single monoamine hormones to multiple amino acid chains.

Steroid Hormones

Hydrophobic, lipid-soluble hormones derived from cholesterol that bind to receptors inside the cytosol or nucleus.

Up-Regulation

The process by which target cells produce and display a greater number of receptors in response to a temporary increase in hormone level in the blood.

Down-Regulation

The process by which target cells decrease the number of receptors displayed in response to prolonged exposure to a high level of hormone in the blood.

Synergistic Effects

Hormone interactions where multiple hormones act on the same target cell to exert the same effect, producing a result more pronounced than any individual hormone alone.

Antagonistic Effects

Hormone interactions where hormones act on the same target cells but produce opposite physiological effects.

Half-Life

The amount of time required for the plasma concentration of a hormone to be reduced by half.

Humoral Stimuli

Hormone secretion triggered by endocrine cells directly responding to changing concentrations of a specific ion or molecule in blood or extracellular fluid.

Tropic Hormones

Hormones that directly control the secretion of hormones from other endocrine glands.

Trophic Hormones

Hormones that induce growth and development in target cells.

Anterior Pituitary (Adenohypophysis)

The glandular portion of the pituitary gland located in the sella turcica that secretes hormones under hypothalamic control.

Posterior Pituitary (Neurohypophysis)

The neural portion of the pituitary gland that stores and releases neurohormones produced by the hypothalamus.

Hypothalamic-Hypophyseal Portal System

A specialized blood supply consisting of capillaries and portal veins that delivers hypothalamic hormones directly to the anterior pituitary gland.

Antidiuretic Hormone (ADH)

A hypothalamic neurohormone stored in the posterior pituitary that promotes water retention by inserting aquaporins into kidney tubule cells.

Oxytocin

A hypothalamic neurohormone stored in the posterior pituitary that stimulates uterine contractions and milk ejection via the milk let-down reflex.

Thyroid-Stimulating Hormone (TSH)

An anterior pituitary tropic hormone stimulated by TRH that promotes growth and hormone secretion of the thyroid gland.

Adrenocorticotropic Hormone (ACTH)

An anterior pituitary tropic hormone stimulated by CRH that promotes development of the adrenal cortex and synthesis of steroid hormones.

Prolactin (PRL)

An anterior pituitary hormone stimulated by TRH and inhibited by dopamine that stimulates mammary gland growth and milk production.

Growth Hormone (GH)

An anterior pituitary hormone regulated by GHRH and somatostatin that promotes metabolic fuel release and triggers hepatic secretion of insulin-like growth factor (IGF).

Colloid

The protein-rich gelatinous material in thyroid follicles containing thyroid hormone precursors and a high concentration of iodine atoms.

Parafollicular Cells

Large cells residing between thyroid follicles that secrete calcitonin to decrease blood calcium levels.

Basal Metabolic Rate (BMR)

The amount of energy required by the body at rest, set by thyroid hormones through ATP consumption and thermoregulation.

Calcitonin

A thyroid hormone secreted by parafollicular cells that lowers blood calcium levels by inhibiting osteoclasts.

Parathyroid Hormone (PTH)

A hormone secreted by chief cells in the parathyroid glands that increases blood calcium ion concentration by stimulating osteoclasts and activating calcitriol.

Zona Glomerulosa

The outer region of the adrenal cortex that produces mineralocorticoids, mainly aldosterone.

Zona Fasciculata

The middle region of the adrenal cortex that produces glucocorticoids, primarily cortisol, and androgenic steroids.

Zona Reticularis

The inner region of the adrenal cortex that produces glucocorticoids and androgenic steroids.

Aldosterone

The primary mineralocorticoid from the adrenal cortex that regulates electrolyte balance, fluid volume, and blood pressure via the renin-angiotensin-aldosterone system (RAAS).

Cortisol

The primary glucocorticoid from the adrenal cortex that mediates the long-term stress response by increasing gluconeogenesis, protein breakdown, and fat release.

Chromaffin Cells

Neuroendocrine cells in the adrenal medulla that release catecholamines (epinephrine and norepinephrine) into the blood during sympathetic nervous system activation.

Pancreatic Islets (Islets of Langerhans)

Small clusters of endocrine cells within the pancreas containing alpha, beta, and delta cells.

Alpha (α) Cells

Pancreatic islet cells that secrete glucagon to increase blood glucose levels.

Beta (β) Cells

Pancreatic islet cells that secrete insulin to lower blood glucose levels.

Gluconeogenesis

The chemical process of synthesizing new glucose molecules from non-carbohydrate sources, such as amino acids and fatty acids.

Ketone Bodies

Acidic fuel molecules formed in the liver during fatty acid breakdown that can cause ketoacidosis if accumulated excessively in the blood.

Involution

The natural process of shrinkage and atrophy that the thymus gland undergoes as an individual ages.

Leptin

A protein hormone secreted by adipocytes that crosses the blood-brain barrier to interact with the hypothalamus to induce satiety.

Atrial Natriuretic Peptide (ANP)

A cardiac hormone released in response to high blood volume that triggers vasodilation and natriuresis to lower blood pressure.

Erythropoietin (EPO)

A kidney hormone released in response to low blood oxygen levels that stimulates red blood cell production (erythropoiesis) in red bone marrow.