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17.13: Key Terms

  • Page ID
    69307
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    Example and Directions
    Words (or words that have the same definition)The definition is case sensitive(Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages](Optional) Caption for Image(Optional) External or Internal Link(Optional) Source for Definition
    (Eg. "Genetic, Hereditary, DNA ...")(Eg. "Relating to genes or heredity")The infamous double helix https://bio.libretexts.org/CC-BY-SA; Delmar Larsen
    Glossary Entries
    Word(s)DefinitionImageCaptionLinkSource
    acromegalydisorder in adults caused when abnormally high levels of GH trigger growth of bones in the face, hands, and feet    
    adenylyl cyclasemembrane-bound enzyme that converts ATP to cyclic AMP, creating cAMP, as a result of G-protein activation    
    adrenal cortexouter region of the adrenal glands consisting of multiple layers of epithelial cells and capillary networks that produces mineralocorticoids and glucocorticoids    
    adrenal glandsendocrine glands located at the top of each kidney that are important for the regulation of the stress response, blood pressure and blood volume, water homeostasis, and electrolyte levels    
    adrenal medullainner layer of the adrenal glands that plays an important role in the stress response by producing epinephrine and norepinephrine    
    adrenocorticotropic hormone (ACTH)anterior pituitary hormone that stimulates the adrenal cortex to secrete corticosteroid hormones (also called corticotropin)    
    alarm reactionthe short-term stress, or the fight-or-flight response, of stage one of the general adaptation syndrome mediated by the hormones epinephrine and norepinephrine    
    aldosteronehormone produced and secreted by the adrenal cortex that stimulates sodium and fluid retention and increases blood volume and blood pressure    
    alpha cellpancreatic islet cell type that produces the hormone glucagon    
    angiotensin-converting enzymethe enzyme that converts angiotensin I to angiotensin II    
    antidiuretic hormone (ADH)hypothalamic hormone that is stored by the posterior pituitary and that signals the kidneys to reabsorb water    
    atrial natriuretic peptide (ANP)peptide hormone produced by the walls of the atria in response to high blood pressure, blood volume, or blood sodium that reduces the reabsorption of sodium and water in the kidneys and promotes vasodilation    
    autocrinechemical signal that elicits a response in the same cell that secreted it    
    beta cellpancreatic islet cell type that produces the hormone insulin    
    calcitoninpeptide hormone produced and secreted by the parafollicular cells (C cells) of the thyroid gland that functions to decrease blood calcium levels    
    chromaffinneuroendocrine cells of the adrenal medulla    
    colloidviscous fluid in the central cavity of thyroid follicles, containing the glycoprotein thyroglobulin    
    cortisolglucocorticoid important in gluconeogenesis, the catabolism of glycogen, and downregulation of the immune system    
    cyclic adenosine monophosphate (cAMP)second messenger that, in response to adenylyl cyclase activation, triggers a phosphorylation cascade    
    delta cellminor cell type in the pancreas that secretes the hormone somatostatin    
    diabetes mellituscondition caused by destruction or dysfunction of the beta cells of the pancreas or cellular resistance to insulin that results in abnormally high blood glucose levels    
    diacylglycerol (DAG)molecule that, like cAMP, activates protein kinases, thereby initiating a phosphorylation cascade    
    downregulationdecrease in the number of hormone receptors, typically in response to chronically excessive levels of a hormone    
    endocrine glandtissue or organ that secretes hormones into the blood and lymph without ducts such that they may be transported to organs distant from the site of secretion    
    endocrine systemcells, tissues, and organs that secrete hormones as a primary or secondary function and play an integral role in normal bodily processes    
    epinephrineprimary and most potent catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called adrenaline    
    erythropoietin (EPO)protein hormone secreted in response to low oxygen levels that triggers the bone marrow to produce red blood cells    
    estrogensclass of predominantly female sex hormones important for the development and growth of the female reproductive tract, secondary sex characteristics, the female reproductive cycle, and the maintenance of pregnancy    
    exocrine systemcells, tissues, and organs that secrete substances directly to target tissues via glandular ducts    
    first messengerhormone that binds to a cell membrane hormone receptor and triggers activation of a second messenger system    
    follicle-stimulating hormone (FSH)anterior pituitary hormone that stimulates the production and maturation of sex cells    
    G proteinprotein associated with a cell membrane hormone receptor that initiates the next step in a second messenger system upon activation by hormone–receptor binding    
    general adaptation syndrome (GAS)the human body’s three-stage response pattern to short- and long-term stress    
    gigantismdisorder in children caused when abnormally high levels of GH prompt excessive growth    
    glucagonpancreatic hormone that stimulates the catabolism of glycogen to glucose, thereby increasing blood glucose levels    
    glucocorticoidshormones produced by the zona fasciculata of the adrenal cortex that influence glucose metabolism    
    goiterenlargement of the thyroid gland either as a result of iodine deficiency or hyperthyroidism    
    gonadotropinshormones that regulate the function of the gonads    
    growth hormone (GH)anterior pituitary hormone that promotes tissue building and influences nutrient metabolism (also called somatotropin)    
    hormonesecretion of an endocrine organ that travels via the bloodstream or lymphatics to induce a response in target cells or tissues in another part of the body    
    hormone receptorprotein within a cell or on the cell membrane that binds a hormone, initiating the target cell response    
    hyperglycemiaabnormally high blood glucose levels    
    hyperparathyroidismdisorder caused by overproduction of PTH that results in abnormally elevated blood calcium    
    hyperthyroidismclinically abnormal, elevated level of thyroid hormone in the blood; characterized by an increased metabolic rate, excess body heat, sweating, diarrhea, weight loss, and increased heart rate    
    hypoparathyroidismdisorder caused by underproduction of PTH that results in abnormally low blood calcium    
    hypophyseal portal systemnetwork of blood vessels that enables hypothalamic hormones to travel into the anterior lobe of the pituitary without entering the systemic circulation    
    hypothalamusregion of the diencephalon inferior to the thalamus that functions in neural and endocrine signaling    
    hypothyroidismclinically abnormal, low level of thyroid hormone in the blood; characterized by low metabolic rate, weight gain, cold extremities, constipation, and reduced mental activity    
    infundibulumstalk containing vasculature and neural tissue that connects the pituitary gland to the hypothalamus (also called the pituitary stalk)    
    inhibinhormone secreted by the male and female gonads that inhibits FSH production by the anterior pituitary    
    inositol triphosphate (IP3)molecule that initiates the release of calcium ions from intracellular stores    
    insulinpancreatic hormone that enhances the cellular uptake and utilization of glucose, thereby decreasing blood glucose levels    
    insulin-like growth factors (IGF)protein that enhances cellular proliferation, inhibits apoptosis, and stimulates the cellular uptake of amino acids for protein synthesis    
    leptinprotein hormone secreted by adipose tissues in response to food consumption that promotes satiety    
    luteinizing hormone (LH)anterior pituitary hormone that triggers ovulation and the production of ovarian hormones, and the production of testosterone    
    melatoninamino acid–derived hormone that is secreted in response to low light and causes drowsiness    
    mineralocorticoidshormones produced by the zona glomerulosa cells of the adrenal cortex that influence fluid and electrolyte balance    
    neonatal hypothyroidismcondition characterized by cognitive deficits, short stature, and other signs and symptoms in people born to people who were iodine-deficient during pregnancy    
    norepinephrinesecondary catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called noradrenaline    
    osmoreceptorhypothalamic sensory receptor that is stimulated by changes in solute concentration (osmotic pressure) in the blood    
    oxytocinhypothalamic hormone stored in the posterior pituitary gland and important in stimulating uterine contractions in labor, milk ejection during breastfeeding, and feelings of attachment (produced by males and females)    
    pancreasorgan with both exocrine and endocrine functions located posterior to the stomach that is important for digestion and the regulation of blood glucose    
    pancreatic isletsspecialized clusters of pancreatic cells that have endocrine functions; also called islets of Langerhans    
    paracrinechemical signal that elicits a response in neighboring cells; also called paracrine factor    
    parathyroid glandssmall, round glands embedded in the posterior thyroid gland that produce parathyroid hormone (PTH)    
    parathyroid hormone (PTH)peptide hormone produced and secreted by the parathyroid glands in response to low blood calcium levels    
    phosphodiesterase (PDE)cytosolic enzyme that deactivates and degrades cAMP    
    phosphorylation cascadesignaling event in which multiple protein kinases phosphorylate the next protein substrate by transferring a phosphate group from ATP to the protein    
    pineal glandendocrine gland that secretes melatonin, which is important in regulating the sleep-wake cycle    
    pinealocytecell of the pineal gland that produces and secretes the hormone melatonin    
    pituitary dwarfismdisorder in children caused when abnormally low levels of GH result in growth retardation    
    pituitary glandbean-sized organ suspended from the hypothalamus that produces, stores, and secretes hormones in response to hypothalamic stimulation (also called hypophysis)    
    PP cellminor cell type in the pancreas that secretes the hormone pancreatic polypeptide    
    progesteronepredominantly female sex hormone important in regulating the female reproductive cycle and the maintenance of pregnancy    
    prolactin (PRL)anterior pituitary hormone that promotes development of the mammary glands and the production of breast milk    
    protein kinaseenzyme that initiates a phosphorylation cascade upon activation    
    second messengermolecule that initiates a signaling cascade in response to hormone binding on a cell membrane receptor and activation of a G protein    
    stage of exhaustionstage three of the general adaptation syndrome; the body’s long-term response to stress mediated by the hormones of the adrenal cortex    
    stage of resistancestage two of the general adaptation syndrome; the body’s continued response to stress after stage one diminishes    
    testosteronesteroid hormone secreted by the testes and important in the maturation of sperm cells, growth and development of the reproductive system, and the development of secondary sex characteristics    
    thymosinshormones produced and secreted by the thymus that play an important role in the development and differentiation of T cells    
    thymusorgan that is involved in the development and maturation of T-cells and is particularly active during infancy and childhood    
    thyroid glandlarge endocrine gland responsible for the synthesis of thyroid hormones    
    thyroid-stimulating hormone (TSH)anterior pituitary hormone that triggers secretion of thyroid hormones by the thyroid gland (also called thyrotropin)    
    thyroxine(also, tetraiodothyronine, T4) amino acid–derived thyroid hormone that is more abundant but less potent than T3 and often converted to T3 by target cells    
    triiodothyronine(also, T3) amino acid–derived thyroid hormone that is less abundant but more potent than T4    
    upregulationincrease in the number of hormone receptors, typically in response to chronically reduced levels of a hormone    
    zona fasciculataintermediate region of the adrenal cortex that produce hormones called glucocorticoids    
    zona glomerulosamost superficial region of the adrenal cortex, which produces the hormones collectively referred to as mineralocorticoids    
    zona reticularisdeepest region of the adrenal cortex, which produces the steroid sex hormones called androgens    

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