Human Biology: Chapter 16 - The Endocrine System

Vocabulary flashcards covering the major glands, hormones, signaling mechanisms, disorders, and homeostatic roles of the endocrine system from Human Biology, 16th Edition.

Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream for body-wide delivery to target cells.

Exocrine Glands

Glands (such as sweat and salivary glands) that secrete their products into ducts carrying them to other organs or outside the body.

Hormones

Chemical signals secreted into the bloodstream used for communication between cells and body organs to regulate function and maintain homeostasis.

Target Cells

Cells that possess specific receptors capable of binding a particular hormone and responding to its signal.

Pheromones

Chemical signals released into the environment that influence the behavior of other individuals.

Peptide Hormones

Hydrophilic, lipophobic hormones composed of short chains of amino acids that bind surface plasma membrane receptors and activate intracellular signaling cascades.

Steroid Hormones

Lipophilic hormones derived from cholesterol that diffuse directly across cell membranes to bind intracellular receptors and regulate gene expression.

Hypothalamus

A region of the brain that integrates the nervous and endocrine systems and regulates the internal environment through the autonomic nervous system.

Posterior Pituitary Gland

The extension of the pituitary gland that stores and releases antidiuretic hormone (ADH) and oxytocin produced by hypothalamic neurosecretory cells.

Antidiuretic Hormone (ADH)

A hormone produced by the hypothalamus and released by the posterior pituitary that promotes water reabsorption by the kidney tubules.

Oxytocin

A hormone released by the posterior pituitary that causes uterine contractions during childbirth and stimulates milk release during nursing.

Anterior Pituitary Gland

An endocrine gland controlled by hypothalamic releasing and inhibiting hormones that produces and secretes hormones such as TSH, ACTH, GH, and PRL.

Thyroid-Stimulating Hormone (TSH)

An anterior pituitary hormone that stimulates the thyroid gland to produce and secrete thyroid hormones.

Adrenocorticotropic Hormone (ACTH)

An anterior pituitary hormone that stimulates the adrenal cortex to produce cortisol and other steroid hormones.

Gonadotropic Hormones

Anterior pituitary hormones (FSH and LH) that stimulate the gonads (testes and ovaries) to produce gametes and sex hormones.

Prolactin (PRL)

A hormone secreted by the anterior pituitary that stimulates the development of mammary glands and milk production after childbirth.

Melanocyte-Stimulating Hormone (MSH)

A hormone produced by the anterior pituitary that stimulates the production of the skin pigment melanin.

Growth Hormone (GH)

An anterior pituitary hormone that promotes skeletal and muscular growth across body tissues.

Pituitary Dwarfism

A condition characterized by abnormally short stature resulting from the underproduction of growth hormone (GH) during childhood.

Gigantism

A disorder characterized by excessive growth and poor health caused by the hypersecretion of growth hormone (GH) during childhood.

Acromegaly

A condition caused by the oversecretion of growth hormone (GH) during adulthood, leading to enlargement of the facial bones, hands, and feet.

Thyroid Gland

A large endocrine gland situated below the larynx that requires iodine to produce thyroid hormones (regulating metabolism) and calcitonin.

Calcitonin

A thyroid hormone that lowers blood $Ca^{2+}$ levels by promoting the deposition of calcium into bones.

Simple Goiter

An abnormal enlargement of the thyroid gland caused by insufficient dietary iodine, which leads to excessive stimulation by TSH.

Hypothyroidism

A clinical deficiency of thyroid hormones characterized by lethargy, weight gain, and cold intolerance in adults, and developmental delays in congenital cases.

Hyperthyroidism

An oversecretion of thyroid hormones often caused by dysregulation or a tumor, marked by hyperactivity and insomnia.

Parathyroid Hormone (PTH)

A hormone secreted by the parathyroid glands in response to low blood calcium that raises blood $Ca^{2+}$ by stimulating osteoclasts and renal calcium reabsorption.

Adrenal Medulla

The inner core of the adrenal gland, controlled by the sympathetic nervous system via the hypothalamus, that secretes epinephrine and norepinephrine during acute stress.

Adrenal Cortex

The outer tissue layer of the adrenal gland, stimulated by ACTH, that releases glucocorticoids and mineralocorticoids to mediate long-term stress responses.

Insulin

A pancreatic hormone secreted by beta cells in the islets of Langerhans that lowers blood glucose by promoting its uptake into muscle, liver, and adipose tissues.

Glucagon

A pancreatic hormone secreted by the islets of Langerhans when blood glucose is low that stimulates the liver to break down glycogen into glucose.

Type 1 Diabetes

An early-onset autoimmune condition where the immune system destroys insulin-producing pancreatic cells, necessitating daily insulin injections.

Type 2 Diabetes

The most common form of diabetes, typically adult-onset and linked to obesity, characterized by insulin resistance in target cells.

Ovaries

Female gonads that produce estrogen and progesterone to regulate the uterine cycle, support egg maturation, and maintain female secondary sex characteristics.

Testes

Male gonads that secrete androgens (principally testosterone) to stimulate sperm maturation and sustain male secondary sex characteristics.

Thymus Gland

A butterfly-shaped gland located beneath the sternum that secretes thymosins and serves as the maturation site for T lymphocytes during childhood.

Pineal Gland

A gland at the base of the brain that secretes melatonin in response to light and darkness to regulate circadian rhythms.

Erythropoietin

A hormone produced by the kidneys that stimulates the bone marrow to accelerate red blood cell production.

Leptin

A hormone secreted by adipose cells that acts on the hypothalamus to induce a feeling of fullness and satiety.

Prostaglandins

Potent local chemical messengers not circulated in the bloodstream that act upon neighboring cells to mediate inflammation, tissue damage, and pain signaling.