Chapter 18: Endocrine System Vocabulary Flashcards

Vocabulary flashcards covering hormone classifications, mechanisms, organs, and functions detailed in Chapter 18.

Endocrine System

Body system consisting of endocrine cells and tissues that produce about 30 different hormones to control and coordinate body processes.

Hormones

Chemical messengers that alter the types, quantities, or activities of enzymes and proteins in target cells, affecting metabolic activities and long-term processes like growth.

Target Cells

Specific cells that possess the receptors needed to bind and read hormonal messages.

Hormone Receptor

A protein molecule to which a particular hormone binds, determining the hormonal sensitivity of a cell.

Amino Acid Derivatives

A class of small hormone molecules structurally related to amino acids.

Peptide Hormones

A class of hormones consisting of chains of amino acids that are not lipid soluble and bind to extracellular receptors.

Lipid Derivatives

A class of lipid-soluble hormones, including steroid hormones derived from cholesterol, that can cross plasma membranes to bind intracellular receptors.

Extracellular Receptors

Receptor proteins located on the outer surface of the plasma membrane that bind non-lipid-soluble hormones.

Intracellular Receptors

Receptors located inside the cytoplasm or nucleus that bind lipid-soluble hormones such as steroids and thyroid hormones.

First Messenger

A hormone that binds to an extracellular receptor on the plasma membrane and promotes the release of a second messenger inside the cell.

Second Messenger

An intermediary molecule (such as cyclic AMP) that appears inside the cell due to first messenger interaction and alters rates of cellular metabolism.

G Protein

An enzyme complex coupled to a membrane receptor that serves as a link between a first messenger and a second messenger.

Negative Feedback

The primary mechanism controlling hormone secretion, wherein a stimulus triggers hormone production that subsequently reduces the intensity of that stimulus.

Pituitary Gland (Hypophysis)

A gland located in the sella turcica inferior to the hypothalamus, connected via the infundibulum, that secretes nine peptide hormones.

Infundibulum

The stalk structure that connects the pituitary gland to the hypothalamus.

Thyroid-Stimulating Hormone (TSH)

Anterior pituitary hormone that targets the thyroid gland to stimulate the release of T3 and T4.

Adrenocorticotropic Hormone (ACTH)

Anterior pituitary hormone that targets the adrenal cortex to stimulate the release of cortisol.

Prolactin (PRL)

Anterior pituitary hormone that targets mammary glands to stimulate milk production.

Growth Hormone (GH)

Anterior pituitary hormone that stimulates tissue growth, protein synthesis, lipid mobilization, and catabolism.

Follicle-Stimulating Hormone (FSH)

A gonadotropin that stimulates ovarian follicle development and estrogen production in females, and sperm maturation in males.

Luteinizing Hormone (LH)

A gonadotropin that induces ovulation and progesterone secretion in females, and testosterone production in males.

Melanocyte-Stimulating Hormone (MSH)

Hormone secreted by the pars intermedia of the pituitary gland that stimulates melanin production in melanocytes.

Antidiuretic Hormone (ADH)

Hormone produced in the hypothalamus and released by the posterior pituitary that promotes renal water reabsorption, elevating blood pressure and volume.

Oxytocin (OXT)

Hormone synthesized in the hypothalamus and released by the posterior pituitary that stimulates uterine smooth muscle contractions during labor and milk ejection.

Follicular Cells

Cells of the thyroid gland that produce thyroid hormones T3 and T4.

C Cells (Parafollicular Cells)

Cells of the thyroid gland that secrete calcitonin to decrease calcium ion concentrations in body fluids.

Parathyroid Hormone (PTH)

Hormone secreted by parathyroid cells in response to low blood calcium concentrations that acts to increase calcium levels in body fluids.

Adrenal Cortex

The superficial region of the adrenal gland subdivided into three zones that produce corticosteroids such as aldosterone, cortisol, and androgens.

Adrenal Medulla

The inner region of the adrenal gland that secretes epinephrine and norepinephrine to trigger fight-or-flight sympathetic responses.

Aldosterone

A mineralocorticoid produced by the zona glomerulosa of the adrenal cortex that stimulates renal conservation of sodium ions and elimination of potassium ions.

Cortisol

A glucocorticoid produced by the zona fasciculata of the adrenal cortex that accelerates glucose synthesis, has anti-inflammatory effects, and reduces white blood cell activity.

Melatonin

Hormone synthesized by pinealocytes in the pineal gland that influences circadian rhythms.

Exocrine Pancreas

The tissue portion of the pancreas (~99% volume) comprising pancreatic acini and ducts that secretes alkaline, enzyme-rich fluid into the digestive tract.

Pancreatic Islets (Islets of Langerhans)

Endocrine cell clusters in the pancreas containing alpha cells and beta cells that regulate blood glucose levels.

Insulin

Hormone secreted by pancreatic beta cells when blood glucose levels rise, accelerating glucose transport into target cells.

Glucagon

Hormone secreted by pancreatic alpha cells when blood glucose levels drop, stimulating glycogen breakdown and glucose release by the liver.

Hyperglycemia

An abnormally high concentration of glucose in the blood.

Diabetes Mellitus

A metabolic disorder characterized by high blood glucose levels exceeding renal reabsorption capacity, causing glucose to appear in the urine.

Type 1 Diabetes Mellitus

A form of diabetes characterized by inadequate insulin production by pancreatic beta cells, typically developing in childhood and requiring daily insulin treatment.

Type 2 Diabetes Mellitus

The most common form of diabetes, characterized by insulin resistance where target tissues fail to respond properly to normal insulin levels; strongly linked to obesity.

Calcitriol

A hormone released by the kidneys that increases blood calcium and phosphate levels.

Erythropoietin (EPO)

A hormone released by the kidneys that stimulates red blood cell (erythrocyte) production.

Renin

An enzyme released by the kidneys that converts circulating angiotensinogen into angiotensin I.

Natriuretic Peptides (ANP and BNP)

Hormones produced by the heart in response to excessive blood volume that promote sodium excretion to lower blood volume and pressure.

Thymosins

A blend of hormones produced by the thymus that promotes the development and maturation of lymphocytes.

Estrogen

Hormone produced by ovarian follicle cells that supports follicle maturation and female secondary sex characteristics.

Progesterone

Hormone produced by the corpus luteum after ovulation that prepares the uterus for embryo implantation and mammary glands for milk production.

Leptin

A hormone produced by adipose tissue that acts as a feedback control mechanism for appetite.

General Adaptation Syndrome (GAS)

The body's multi-phase stress response system designed to respond to factors threatening homeostasis, consisting of alarm, resistance, and exhaustion phases.

Alarm Phase

The immediate first phase of GAS directed by the sympathetic division of the ANS, dominated by epinephrine, which mobilizes glucose energy reserves for fight-or-flight responses.

Resistance Phase

The second phase of GAS occurring if stress lasts longer than a few hours; dominated by cortisol and aldosterone to shift energy metabolism to lipids and amino acids while preserving glucose for nervous tissue.

Exhaustion Phase

The terminal phase of GAS occurring when homeostatic mechanisms break down, characterized by severe potassium depletion from prolonged aldosterone action and potential organ failure.