Essentials of Human Anatomy & Physiology - Chapter 9: The Endocrine System

Vocabulary practice flashcards covering the key terms, mechanisms of hormone action, endocrine glands, and associated hormones from Chapter 9.

Endocrinology

The scientific study of hormones and endocrine organs.

Hormone

A chemical messenger produced by specialized cells, secreted into extracellular fluids, and transferred by blood to regulate the activity of target cells.

Target Cells

Specific cells or organs that possess specific protein receptors capable of binding a particular hormone to alter cellular activity.

Direct Gene Activation

The mechanism of hormone action used by steroid hormones and thyroid hormone, in which the hormone diffuses through the plasma membrane, enters the nucleus, binds a receptor protein, and attaches to DNA to activate gene transcription and protein synthesis.

Second-Messenger System

The mechanism of hormone action used by protein and peptide hormones, where binding to a membrane receptor activates an intracellular enzyme to generate a secondary messenger molecule like cyclic AMP ($\text{cAMP}$).

Hormonal Stimuli

The category of endocrine gland stimulation where endocrine organs are activated to release their hormones by other hormones.

Humoral Stimuli

The category of endocrine gland stimulation triggered by changing blood levels of specific ions and nutrients.

Neural Stimuli

The category of endocrine gland stimulation where nerve fibers directly stimulate hormone release.

Oxytocin

A peptide hormone produced by the hypothalamus and stored in the posterior pituitary that stimulates uterine contractions during labor and triggers the milk let-down reflex.

Antidiuretic Hormone (ADH)

A peptide hormone released by the posterior pituitary that reduces urine volume by promoting water reabsorption in the kidneys and increases blood pressure.

Growth Hormone (GH)

A general metabolic protein hormone secreted by the anterior pituitary that directs growth of skeletal muscles and long bones, promotes amino acid incorporation into proteins, and breaks down fats.

Prolactin (PRL)

A protein hormone secreted by the anterior pituitary that stimulates and maintains milk production in female mammary glands after childbirth.

Follicle-Stimulating Hormone (FSH)

A tropic protein hormone secreted by the anterior pituitary that stimulates follicle development in ovaries and sperm development in testes.

Luteinizing Hormone (LH)

A tropic protein hormone secreted by the anterior pituitary that triggers ovulation in females and stimulates testosterone production in males.

Thyroid-Stimulating Hormone (TSH)

A tropic protein hormone (also called thyrotropic hormone) secreted by the anterior pituitary that regulates the growth and activity of the thyroid gland.

Adrenocorticotropic Hormone (ACTH)

A tropic protein hormone secreted by the anterior pituitary that regulates the endocrine activity of the adrenal cortex.

Melatonin

An amine hormone secreted by the pineal gland that regulates biological rhythms, including the body's sleep/wake cycle.

Thyroid Hormone

The major metabolic hormone secreted by the thyroid gland, consisting of thyroxine ($T_4$) and triiodothyronine ($T_3$), which controls glucose oxidation rates.

Calcitonin

A peptide hormone produced by thyroid parafollicular cells that lowers blood calcium ion levels by stimulating calcium deposition on bone matrix.

Parathyroid Hormone (PTH)

A hypercalcemic peptide hormone secreted by the parathyroid glands that raises blood calcium levels by stimulating osteoclasts to degrade bone.

Thymosin

A peptide hormone secreted by the thymus that programs and matures T lymphocytes for immune system development.

Mineralocorticoids

Steroid hormones (primarily aldosterone) produced by the outer layer of the adrenal cortex that regulate sodium and potassium ion concentrations and water balance in the kidneys.

Glucocorticoids

Steroid hormones (including cortisone and cortisol) secreted by the middle layer of the adrenal cortex that promote normal cell metabolism, raise blood glucose levels, and decrease inflammation.

Epinephrine and Norepinephrine

Catecholamine amine hormones released by the adrenal medulla during short-term stress to increase heart rate, blood pressure, and blood glucose levels.

Insulin

A hypoglycemic protein hormone secreted by pancreatic beta cells that decreases blood glucose levels by accelerating cellular glucose uptake and glycogen storage.

Glucagon

A hyperglycemic protein hormone secreted by pancreatic alpha cells that raises blood glucose levels by stimulating the liver to break down stored glycogen into glucose.

Estrogens

Steroid hormones produced by the ovaries that stimulate female secondary sex characteristics, mature female reproductive organs, and help regulate the menstrual cycle.

Progesterone

A steroid hormone produced by the ovaries that works with estrogen to regulate the menstrual cycle, promote uterine lining growth, and assist embryo implantation.

Testosterone

The principal androgen steroid hormone secreted by the testes that regulates male secondary sex characteristics, reproductive system maturation, and sperm cell production.

Erythropoietin

A glycoprotein hormone produced by the kidneys in response to hypoxia (low blood oxygen levels) that stimulates red blood cell production in bone marrow.

Leptin

A peptide hormone secreted by adipose tissue in response to fatty food consumption that acts on the brain to suppress appetite and increase energy expenditure.