Endocrine System Vocabulary Flashcards

Vocabulary flashcards covering cellular communication, hormone classes, pituitary and thyroid functions, feedback mechanisms, stress responses, and endocrine disorders based on the lecture notes.

Direct communication

Intercellular communication where ions and molecules pass through gap junctions between adjacent cells of the same type.

Autocrine communication

Intercellular communication where a cell releases a chemical mediator into extracellular fluid that affects the same type of cell that secreted it.

Paracrine communication

Intercellular communication where a cell releases a mediator into extracellular fluid to affect neighboring cells, producing localized control.

Endocrine communication

Intercellular communication where endocrine cells release hormones into tissue fluid and the bloodstream to act on distant target cells with specific receptors.

Synaptic communication

Intercellular communication where a neuron releases neurotransmitters across a synapse to deliver a fast, directed message to a specific destination.

Hormone

A chemical messenger that relays information and instructions between cells in distant parts of the body by binding to target cells with specific receptors.

Amino acid derivatives

Small hormone molecules related to amino acids, including tyrosine derivatives (thyroid hormones, epinephrine, norepinephrine, dopamine) and tryptophan derivatives (serotonin, melatonin).

Peptide hormones

Chains of amino acids often synthesized as inactive prohormones, including glycoproteins, short polypeptides, and proteins.

Lipid derivatives

Hormones consisting of eicosanoids derived from arachidonic acid and steroid hormones derived from cholesterol.

Up-regulation

The process in which target cells increase their receptor number and become more sensitive when a hormone is absent or present at low levels.

Down-regulation

The process in which target cells decrease their receptor number and become less sensitive when a hormone is present at high levels.

Carrier proteins

Transport proteins bound to thyroid and steroid hormones in blood that create a substantial circulating reserve and extend functional hormone lifespan.

First messenger

An extracellular hormone that cannot cross the plasma membrane and binds to a cell-surface receptor to activate a G protein.

Second messenger

An intracellular molecule, such as cyclic adenosine monophosphate or calcium ion, that amplifies signal binding and alters cell enzyme activity.

Anterior lobe of the pituitary gland

The glandular portion (adenohypophysis) of the pituitary gland controlled by hypothalamic releasing and inhibiting hormones via the hypophyseal portal system.

Posterior lobe of the pituitary gland

The neural portion (neurohypophysis) of the pituitary gland that stores and releases antidiuretic hormone and oxytocin produced in the hypothalamus.

Thyroid-stimulating hormone

An anterior pituitary tropic hormone stimulated by thyrotropin-releasing hormone that promotes normal growth, development, and secretory activity of the thyroid.

Adrenocorticotropic hormone

An anterior pituitary tropic hormone stimulated by corticotropin-releasing hormone that targets the adrenal cortex to release corticosteroids/glucocorticoids.

Follicle-stimulating hormone

An anterior pituitary gonadotropin that promotes ovarian follicle development in females and sperm development in males.

Luteinizing hormone

An anterior pituitary gonadotropin that induces ovulation and progesterone secretion in females, and stimulates androgen production in males.

Prolactin

An anterior pituitary non-tropic hormone that targets female breasts/mammary glands to promote gland development and milk production.

Growth hormone

An anterior pituitary non-tropic hormone that promotes protein synthesis, fat utilization, liver somatomedins, and long bone and skeletal muscle growth.

Melanocyte-stimulating hormone

An anterior pituitary non-tropic hormone that stimulates melanin production by skin and hair melanocytes, virtually nonfunctional in most adults.

Antidiuretic hormone

A peptide hormone synthesized in the hypothalamus and released by the posterior pituitary that targets the kidneys to promote water retention.

Oxytocin

A peptide hormone synthesized in the hypothalamus and released by the posterior pituitary that stimulates uterine contractions, milk ejection, and prostate contraction.

Thyroid peroxidase

An enzyme at the apical surface of thyroid follicle cells that carries out the enzymatic conversion of iodide to iodine and its binding to tyrosines in thyroglobulin.

Thyroglobulin

A protein secreted into thyroid colloid containing linked iodinated tyrosines that form stored triiodothyronine and thyroxine.

Calcitonin

A hormone produced by thyroid parafollicular cells that lowers blood calcium by reducing osteoclast activity and increasing renal calcium excretion.

Parathyroid hormone

A hormone produced by parathyroid principal/chief cells that raises blood calcium by activating osteoclasts, increasing renal calcium reabsorption, and promoting calcitriol formation.

Calcitriol

A hormone produced by the kidneys that raises blood calcium ion by increasing intestinal absorption of calcium salts.

Aldosterone

A corticosteroid released by the adrenal cortex's zona glomerulosa that increases renal sodium ion reabsorption and urinary potassium ion loss.

Renin-angiotensin-aldosterone system

A hormonal cascade triggered by renal renin release that generates angiotensin II to stimulate aldosterone, antidiuretic hormone, thirst, fluid retention, and elevated blood pressure.

Antagonistic effect

A hormone interaction in which two hormones have opposite effects, with the net outcome depending on their relative balance.

Synergistic effect

A hormone interaction in which two hormones produce an additive effect.

Permissive effect

A hormone interaction in which one hormone is required for another hormone to produce its effect.

Integrative effect

A hormone interaction in which two hormones produce different but complementary results.

Alarm phase

The initial phase of General Adaptation Syndrome dominated by epinephrine, producing a fight-or-flight response, mobilizing glycogen/lipid reserves, and elevating heart rate.

Resistance phase

The second phase of General Adaptation Syndrome dominated by glucocorticoids, shifting peripheral tissue fuel to lipids and amino acids to conserve glucose for nervous tissue.

Exhaustion phase

The final phase of General Adaptation Syndrome where energy reserves are depleted, leading to collapse of homeostatic regulation, electrolyte imbalance, and organ failure.

Melatonin

A pinealocyte hormone released by the pineal gland during darkness that influences day-night cycles, sleep, appetite, and body temperature.

Erythropoietin

A kidney hormone released in response to decreased renal blood flow and oxygen that stimulates red bone marrow to increase red blood cell production.

Natriuretic peptides

Hormones (ANP and BNP) released by heart walls in response to stretch that lower blood pressure, induce vasodilation, and oppose sodium and water retention.

Thymosins

Hormones secreted by the thymus that are essential for the development of thymus-derived lymphocytes in the immune response.

Leptin

A peptide hormone produced by adipose tissue that provides feedback control of appetite and maintains normal gonadotropin-releasing hormone synthesis.

Pituitary growth failure

A condition caused by growth hormone deficiency, characterized by retarded growth, abnormal fat distribution, and postprandial low blood glucose.

Gigantism

A condition caused by growth hormone excess characterized by excessive body growth.

Diabetes insipidus

A disease caused by antidiuretic hormone deficiency or insensitivity, characterized by polyuria, dehydration, and extreme thirst.

Syndrome of inappropriate antidiuretic hormone secretion

A condition caused by excess antidiuretic hormone secretion, characterized by increased body weight and water content.

Hypothyroidism

A condition caused by thyroid hormone deficiency characterized by low metabolic rate, low body temperature, and impaired physical and mental development.

Graves disease

An autoimmune hyperthyroid condition caused by excess thyroid hormone, characterized by high metabolic rate and elevated body temperature.

Hypoparathyroidism

A condition caused by parathyroid hormone deficiency, resulting in low blood calcium ion, muscular weakness, dense bones, and tetany.

Hyperparathyroidism

A condition caused by parathyroid hormone excess, leading to high blood calcium ion, weak brittle bones, and neurological, mental, and muscular problems.

Type 1 diabetes mellitus

A metabolic disorder caused by insulin deficiency, characterized by high blood glucose, impaired glucose use, reliance on lipids for energy, and glycosuria.

Type 2 diabetes

A metabolic disorder produced by target tissue insensitivity to insulin.

Hypoaldosteronism

A condition caused by aldosterone deficiency, characterized by polyuria, low blood volume, high blood potassium ion, and low blood sodium ion.

Aldosteronism

A condition caused by aldosterone excess, characterized by sodium ion and water retention, increased body weight, and low blood potassium ion.

Addison disease

A disorder caused by glucocorticoid deficiency, characterized by an inability to tolerate stress, mobilize energy reserves, or maintain normal blood glucose.

Cushing disease

A disorder caused by glucocorticoid excess, characterized by excessive breakdown of tissue protein and lipids and impaired glucose metabolism.

Pheochromocytoma

A hypersecreting tumor causing excess epinephrine and norepinephrine, leading to high metabolic rate, body temperature, heart rate, and blood glucose.