Chapter 12 – The Endocrine System: Glands and Hormones

Vocabulary flashcards summarizing key endocrine terms, glands, hormones, disorders, and clinical applications from Chapter 12.

Endocrine system

Body-wide network of hormone-secreting glands that regulate growth, metabolism, reproduction, and homeostasis.

Hormone

Chemical messenger released into tissue fluids or blood that binds receptors on target cells to alter their activity.

Target tissue

Specific cell or organ that contains receptors for, and responds to, a particular hormone.

Receptor (hormonal)

Protein on or in a cell that selectively binds a hormone and initiates the cellular response.

Negative feedback

Control mechanism in which rising hormone or regulated variable levels inhibit further hormone release.

Amino-acid–based hormone

Hormone class built from proteins or amino-acid derivatives (e.g., insulin, epinephrine).

Steroid hormone

Lipid-soluble hormone derived from cholesterol, produced by adrenal cortex and sex glands (e.g., cortisol, estrogen).

Prostaglandin

Locally acting lipid messenger made by most tissues; can constrict or dilate vessels, promote inflammation, or trigger uterine contractions.

Pituitary gland (hypophysis)

“Master gland” beneath the brain; stores or secretes multiple hormones that regulate other endocrine glands.

Infundibulum

Stalk connecting the hypothalamus to the pituitary gland.

Anterior pituitary (adenohypophysis)

Front lobe of pituitary that synthesizes GH, TSH, ACTH, PRL, FSH, and LH.

Posterior pituitary (neurohypophysis)

Back lobe of pituitary that stores and releases hypothalamic ADH and oxytocin.

Hypothalamus

Brain region that produces releasing/inhibiting hormones and synthesizes ADH and oxytocin.

Growth hormone (GH)

Anterior pituitary hormone that stimulates tissue growth and increases blood glucose.

Thyroid-stimulating hormone (TSH)

Anterior pituitary hormone that prompts the thyroid to secrete T3 and T4.

Adrenocorticotropic hormone (ACTH)

Anterior pituitary hormone that triggers cortisol release from the adrenal cortex.

Prolactin (PRL)

Anterior pituitary hormone that stimulates breast milk production.

Follicle-stimulating hormone (FSH)

Anterior pituitary gonadotropin that stimulates ovarian follicle growth and sperm production.

Luteinizing hormone (LH)

Anterior pituitary gonadotropin that triggers ovulation and stimulates testosterone secretion.

Antidiuretic hormone (ADH)

Posterior pituitary hormone that promotes water reabsorption by kidneys, reducing urine output.

Oxytocin

Posterior pituitary hormone that induces uterine contractions and milk let-down.

Thyroid gland

Butterfly-shaped gland in neck producing thyroxine (T4) and triiodothyronine (T3) to regulate metabolism.

Thyroxine (T4)

Principal thyroid hormone containing four iodine atoms; converted to T3 in tissues.

Triiodothyronine (T3)

Active thyroid hormone (three iodine atoms) that raises metabolic rate and heat production.

Goiter

Enlargement of the thyroid gland, usually due to excess TSH stimulation.

Hypothyroidism

State of deficient thyroid hormone leading to weight gain, cold intolerance, and fatigue.

Hyperthyroidism

Excess thyroid hormone producing weight loss, heat intolerance, and nervousness.

Hashimoto thyroiditis

Autoimmune destruction of the thyroid causing chronic hypothyroidism.

Graves disease

Autoimmune stimulation of the thyroid resulting in hyperthyroidism.

Parathyroid glands

Four small glands on posterior thyroid that secrete PTH to regulate blood calcium.

Parathyroid hormone (PTH)

Hormone that raises blood calcium by stimulating bone resorption and activating vitamin D.

Calcitriol (Vitamin D3)

Kidney-activated hormone that works with PTH to increase blood calcium.

Hyperparathyroidism

Excess PTH causing elevated blood calcium, weak bones, and kidney stones.

Tetany

Muscle spasms resulting from low blood calcium, often due to hypoparathyroidism.

Adrenal gland

Endocrine organ atop each kidney consisting of an outer cortex and inner medulla.

Adrenal medulla

Inner adrenal region that secretes epinephrine for fight-or-flight responses.

Epinephrine (adrenaline)

Catecholamine that increases heart rate, blood pressure, and blood glucose during stress.

Adrenal cortex

Outer adrenal region that releases glucocorticoids, mineralocorticoids, and androgens.

Glucocorticoid

Adrenal cortical steroid (e.g., cortisol) that elevates blood glucose and suppresses immunity.

Cortisol

Primary glucocorticoid involved in stress and starvation responses; raises blood sugar.

Mineralocorticoid

Adrenal cortical steroid (e.g., aldosterone) that regulates sodium and potassium balance.

Aldosterone

Mineralocorticoid that promotes renal sodium reabsorption and potassium excretion.

Addison disease

Adrenal cortex hyposecretion leading to weakness, low blood pressure, and weight loss.

Cushing syndrome

Adrenal cortex hypersecretion (or corticosteroid therapy) causing hyperglycemia and central obesity.

Pancreatic islets (Islets of Langerhans)

Endocrine clusters in the pancreas that secrete insulin and glucagon.

Insulin

Beta-cell hormone that lowers blood glucose by promoting cellular uptake and storage.

Glucagon

Alpha-cell hormone that raises blood glucose by stimulating glycogen breakdown and gluconeogenesis.

Diabetes mellitus type 1

Autoimmune destruction of beta cells causing absolute insulin deficiency; requires insulin therapy.

Diabetes mellitus type 2

Condition of insulin resistance, often associated with obesity and managed with lifestyle changes.

Gestational diabetes

Glucose intolerance first recognized during pregnancy.

Metabolic syndrome

Cluster of insulin resistance, obesity, hypertension, and dyslipidemia increasing cardiovascular risk.

Pineal gland

Cone-shaped gland posterior to midbrain that secretes melatonin.

Melatonin

Pineal hormone that influences sleep–wake cycles and may delay puberty onset.

Leptin

Adipose-derived hormone that helps regulate appetite and energy balance.

Erythropoietin (EPO)

Kidney hormone stimulating red blood cell production in bone marrow.

Atrial natriuretic peptide (ANP)

Heart atria hormone that promotes sodium (and water) loss to lower blood pressure.

Osteocalcin

Bone-derived hormone involved in glucose regulation and bone mineralization.

Placental hormones

Hormones such as hCG, estrogen, and progesterone that support pregnancy.

Stress response hormones

Epinephrine, cortisol, ADH, and growth hormone released during physiological stress.

Medical use: Cortisol

Administered pharmacologically to treat inflammation and autoimmune disorders.

Medical use: Oxytocin

Used clinically to induce or augment labor and control postpartum bleeding.

Medical use: Growth hormone

Prescribed for dwarfism and other GH deficiency states.

Medical use: Thyroid hormone

Synthetic T4 given to correct hypothyroidism.

Medical use: Androgens

Testosterone preparations used to promote tissue building and recovery.