Glands and Hormones: Human Endocrine System

Vocabulary practice flashcards covering the components, glands, hormones, and comparative control mechanisms of the human endocrine system.

Endocrine system

A chemical communication network of ductless glands that synthesise and secrete hormones directly into the blood to coordinate body activities.

Hormone

A chemical messenger produced by a gland and transported through the bloodstream to regulate distant target organs and tissues.

Gland

An organ or tissue specialised to synthesise and release substances into the body.

Target

A specific cell or organ possessing complementary receptors for a particular hormone.

Pituitary gland

Known as the master gland; located in the brain, it secretes growth hormone to govern developmental timing and hormones such as TSH that stimulate other endocrine glands.

TSH (Thyroid-stimulating hormone)

A hormone secreted by the pituitary gland that stimulates the thyroid gland.

Growth hormone

A hormone produced by the pituitary gland responsible for governing developmental timing.

Thyroid gland

An endocrine gland situated in the neck that produces thyroxine to set the basal metabolic rate.

Thyroxine

A hormone secreted by the thyroid gland that sets basal metabolic rate, regulating energy consumption, digestion, and protein synthesis.

Pancreas

An organ functioning as both an exocrine and endocrine gland whose islet cells release insulin and glucagon directly into blood vessels.

Islet cells

Specialised clusters of endocrine cells within the pancreas that secrete insulin and glucagon into the blood to maintain stable blood glucose levels.

Insulin

A hormone secreted by pancreatic islet cells directly into blood vessels to maintain stable blood glucose levels.

Glucagon

A hormone produced and secreted by pancreatic islet cells to maintain stable blood glucose levels.

Adrenal glands

Endocrine glands sitting atop each kidney that secrete adrenaline and cortisol during stress.

Adrenaline

A hormone secreted by the adrenal glands during stress that boosts heart rate, pupil dilation, and blood glucose, providing sustained effects in the bloodstream.

Cortisol

A hormone secreted by the adrenal glands in response to stress that boosts available blood glucose levels.

Target cell

A cell that displays complementary protein receptors on its surface or in its cytoplasm, binding hormones like a lock and key to trigger a cellular response.

Receptor protein

A specific protein located on the surface or inside the cytoplasm of target cells that complements and binds circulating hormones.

Nervous control

A communication pathway using electrical impulses transmitted along neurones, characterized by rapid transmission (milliseconds) and brief, localised responses.

Endocrine control

A communication pathway using chemical hormones transported via the bloodstream, characterized by slower speeds (seconds to days) and sustained, widespread responses.

Reflex arc

A neural circuit that triggers instant withdrawal by bypassing the brain through short neurone pathways for rapid, involuntary, and localised action.

Homeostasis

The regulation of steady internal conditions—such as water balance, basal metabolic rate, and menstrual cycles—requiring sustained endocrine signalling over days or years.