Endocrine System Overview – Lecture Vocabulary

Vocabulary flashcards summarising the key endocrine terms, hormones, glands, and disorders discussed in the lecture transcript.

Hypothalamus

Brain region that releases tropic hormones which control the anterior pituitary and coordinate many endocrine reflexes.

Tropic Hormone

A hormone whose target is another endocrine gland, stimulating or inhibiting its secretion.

Anterior Pituitary (Adenohypophysis)

Glandular lobe of the pituitary that produces six major hormones (FSH, LH, ACTH, TSH, PRL, GH).

Posterior Pituitary (Neurohypophysis)

Neural lobe of the pituitary that stores and releases hypothalamic hormones (oxytocin and ADH).

Follicle-Stimulating Hormone (FSH)

Anterior pituitary tropic hormone that stimulates gamete (sperm & egg) production in the gonads.

Luteinizing Hormone (LH)

Anterior pituitary tropic hormone that triggers ovulation and stimulates interstitial cells to secrete testosterone.

Adrenocorticotropic Hormone (ACTH)

Anterior pituitary hormone that targets the adrenal cortex to release its steroid hormones.

Thyroid-Stimulating Hormone (TSH)

Anterior pituitary hormone that prompts the thyroid gland to secrete thyroid hormone.

Prolactin (PRL)

Anterior pituitary hormone that promotes milk production by mammary glands.

Growth Hormone (GH) / Somatotropin

Anterior pituitary hormone that stimulates widespread tissue growth and liver release of IGFs.

Somatostatin

Hypothalamic hormone that inhibits growth hormone release (GH-inhibiting hormone).

Gigantism

Excess GH secretion in childhood causing abnormal overall growth and very tall stature.

Acromegaly

Excess GH secretion in adulthood leading to bone thickening of hands, face, and feet.

Pituitary Dwarfism

Growth retardation due to GH hyposecretion during childhood; body proportions remain normal but smaller.

Thyroid Hormone (T3 & T4)

Iodine-containing amine hormones that increase metabolic rate, heat production, and development.

Triiodothyronine (T3)

The more active thyroid hormone form containing three iodine atoms.

Thyroxine (T4)

Predominant thyroid secretion with four iodines; converted to T3 in tissues.

Calcitonin

Thyroid parafollicular-cell hormone that lowers blood calcium by stimulating osteoblasts.

Parathyroid Hormone (PTH)

Chief-cell hormone that raises blood calcium by activating osteoclasts and promoting renal/intestine Ca²⁺ reabsorption.

Osteoclast

Bone-resorbing cell activated by PTH to release calcium into blood.

Osteoblast

Bone-building cell stimulated by calcitonin to deposit calcium in bone matrix.

Goiter

Enlarged thyroid gland, often from iodine deficiency or thyroid disorders.

Zona Glomerulosa

Outer adrenal cortex layer that secretes mineralocorticoids, chiefly aldosterone.

Aldosterone

Mineralocorticoid that increases Na⁺ reabsorption and K⁺ excretion in kidneys to support blood pressure.

Zona Fasciculata

Middle adrenal cortex layer that releases glucocorticoids such as cortisol.

Cortisol

Glucocorticoid involved in long-term stress response; elevates blood glucose, suppresses immunity, and promotes protein & fat catabolism.

Zona Reticularis

Inner adrenal cortex layer that produces weak androgens contributing to pre-pubertal sex characteristics.

Catecholamines

Adrenal medulla hormones (epinephrine & norepinephrine) released during sympathetic ‘fight-or-flight’ response.

Epinephrine

Major adrenal medulla catecholamine (≈80%) that increases heart rate, bronchodilation, and blood glucose.

Norepinephrine

Catecholamine (≈20%) acting as hormone and neurotransmitter; complements epinephrine in stress responses.

Gluconeogenesis

Hepatic formation of glucose from non-carbohydrate sources (amino acids, glycerol); stimulated by cortisol and glucagon.

Lipolysis

Breakdown of triglycerides into free fatty acids; promoted by GH, cortisol, and catecholamines.

Alpha Cells (Pancreatic)

Islet cells that secrete glucagon to raise blood glucose (think G-A in ‘GAl’ or ‘GABA’ mnemonic).

Beta Cells (Pancreatic)

Islet cells that secrete insulin to lower blood glucose (B-I in ‘BIGA’ mnemonic).

Insulin

Beta-cell hormone that facilitates cellular glucose uptake, glycogen formation, and fat storage, lowering blood sugar.

Glucagon

Alpha-cell hormone that raises blood sugar by stimulating glycogenolysis and gluconeogenesis in the liver.

Leptin

Adipose-derived hormone that signals satiety to the hypothalamus and suppresses appetite.

Myostatin

Muscle-derived growth inhibitor; deficiency or blockade causes extreme muscle hypertrophy with health risks.

Cushing’s Disease

Hypersecretion of cortisol (often from ACTH-producing tumor) causing hyperglycemia, muscle wasting, ‘moon face’, and hypertension.

Hypothyroidism

Low thyroid hormone state leading to weight gain, cold intolerance, fatigue, and possible goiter.

Hyperthyroidism

Excess thyroid hormone causing weight loss, heat intolerance, tachycardia, and possibly exophthalmos.

Humoral Stimulus

Endocrine reflex triggered by changes in blood levels of ions or nutrients (e.g., Ca²⁺ for PTH).

Negative Feedback

Homeostatic mechanism where rising hormone levels inhibit further hormone release to maintain balance.