Hormones and the Endocrine System

Vocabulary flashcards related to hormones and the endocrine system.

Hormone

A secreted molecule that circulates through the body and stimulates specific cells.

Endocrine signaling

Chemical signaling by hormones; maintains homeostasis, mediates responses to stimuli, regulates growth and development, and triggers changes underlying sexual maturity and reproduction.

Local regulators

Molecules that act over short distances, reaching target cells solely by diffusion.

Paracrine signaling

Signaling where the target cells lie near the secreting cells.

Autocrine signaling

Signaling where the target cell is also the secreting cell.

Synapses

Specialized junctions where neurons communicate with target cells.

Neurotransmitters

Secreted molecules that diffuse short distances and bind to receptors on target cells at synapses.

Neuroendocrine signaling

Signaling where specialized neurosecretory cells secrete neurohormones that diffuse from nerve endings into the bloodstream.

Water-soluble hormones

Hormones secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors.

Lipid-soluble hormones

Hormones that diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells; they bind to receptors in the cytoplasm or nucleus of the target cells.

Endocrine glands

Ductless organs where endocrine cells are often grouped.

Exocrine glands

Glands that have ducts to carry secreted substances onto body surfaces or into body cavities.

Hypothalamus

Located in the brain, it coordinates endocrine signaling by receiving information from nerves throughout the body and initiates appropriate neuroendocrine signals; signals from it travel to the pituitary gland.

Posterior pituitary

Stores and secretes hormones that are made in the hypothalamus.

Anterior pituitary

Makes and releases hormones under regulation of the hypothalamus.

Simple endocrine pathway

Endocrine cells respond directly to a stimulus by secreting a particular hormone; the hormone travels in the bloodstream to target cells, where it interacts with its specific receptors.

Simple neuroendocrine pathway

The stimulus is received by a sensory neuron, which stimulates a neurosecretory cell; the neurosecretory cell secretes a neurohormone, which enters the bloodstream and travels to target cells.

Antidiuretic hormone (ADH)

Regulates physiology and behavior; one of the two posterior pituitary hormones.

Oxytocin

Regulates milk secretion by the mammary glands; one of the two posterior pituitary hormones.

Tropic hormones

Hormones that target other endocrine glands.

Thyrotropin-releasing hormone (TRH)

Secreted by the hypothalamus, causing the anterior pituitary to secrete thyroid-stimulating hormone (TSH).

Thyroid-stimulating hormone (TSH)

Stimulates release of thyroid hormone by the thyroid gland.

Parathyroid hormone (PTH)

Homeostatic regulation is vital; released by the parathyroid glands when Ca2+ levels fall below a set point.

Adrenal glands

Located atop the kidneys; consists of the adrenal medulla (inner portion) and adrenal cortex (outer portion).

Adrenal medulla

Secretes epinephrine (adrenaline) and norepinephrine (noradrenaline).

Catecholamines

Members of a class of compounds that coordinate a set of physiological responses that comprise the “fight-or-flight” response.