Endocrine System and Hormonal Physiology

Comprehensive vocabulary flashcards covering endocrine anatomy, hormone physiology, associated pathologies, and pharmacological treatments based on the lecture materials.

Endocrine Gland

Ductless glands that synthesize and secrete hormones directly into the bloodstream to reach target cells with specific receptors.

Exocrine Gland

Glands that secrete their secretory products into a duct system rather than directly into the blood.

Infundibulum

The stalk that connects the pituitary gland to the hypothalamus.

Adenohypophysis

The anterior lobe of the pituitary gland composed of glandular tissue, subdivided into the pars tuberalis, pars intermedia, and pars distalis.

Neurohypophysis

The posterior lobe of the pituitary gland consisting of neural secretory tissue, subdivided into the infundibular stalk and pars nervosa.

Hypothalamo-hypophyseal portal system

A system of blood vessels consisting of two capillary beds connected by portal veins that carry hormone releasing factors from the hypothalamus to the adenohypophysis.

Herring Bodies

Axonal dilatations in the pars nervosa where hormones produced by the hypothalamus accumulate.

Thyroid Follicle

The structural and functional unit of the thyroid gland consisting of a layer of cuboidal/columnar epithelium that secretes $T_3$ and $T_4$.

Parafollicular cells (C-cells)

Neuroendocrine cells located between thyroid follicles that secrete calcitonin.

Parathyroid Hormone (PTH)

A peptide hormone synthesized by principal cells that increases plasma $Ca^{2+}$ through bone resorption and renal reabsorption.

Adrenal Cortex

The outer portion of the adrenal gland derived from mesoderm that secretes steroid hormones.

Adrenal Medulla

The inner portion of the adrenal gland derived from neural crest cells that secretes catecholamines such as adrenaline and noradrenaline.

Zona Glomerulosa

The outermost layer of the adrenal cortex that produces mineralocorticoids, primarily aldosterone.

Zona Fasciculata

The broadest middle zone of the adrenal cortex that produces glucocorticoids like cortisol and androgenic sex hormones.

Zona Reticularis

The innermost layer of the adrenal cortex that produces glucocorticoids and androgens.

Hassall’s corpuscle

Concentric lamellated structures formed by keratinized epithelial cells, characteristic of the thymic medulla.

Psammoma bodies

Basophilic extracellular calcified concretions found in the pineal gland that serve as a midline landmark on X-rays.

Islets of Langerhans

Endocrine clusters in the pancreas containing Alpha cells (glucagon), Beta cells (insulin), and Delta cells (somatostatin).

Leydig cells

Cells located between seminiferous tubules in the testes that produce testosterone.

Ectopic hormones

Hormones synthesized by cells outside of the normal endocrine glands, such as $ACTH$ produced by a lung tumor.

Metabolism of Catecholamines

Degradation by Monoamine Oxidase (MAO) and Catechol O-methyltransferase (COMT) to produce vanillylmandelic acid (VMA).

Gigantism

A disorder caused by the hypersecretion of Growth Hormone ($GH$) in children.

Acromegaly

A disorder caused by the hypersecretion of Growth Hormone ($GH$) in adults.

Sheehan syndrome

Acute necrosis of the anterior pituitary secondary to postpartum hemorrhage and shock.

Diabetes Insipidus

A condition characterized by $ADH$ deficiency leading to polyuria (>3L/24h) and polydipsia.

Cushing Disease

Excess production of $ACTH$ by a pituitary adenoma leading to hypercortisolism.

Conn Syndrome

Primary aldosteronism resulting in sodium retention, hypertension, and hypokalemia.

Addison Disease

Adrenocortical insufficiency due to the destruction or dysfunction of the entire adrenal cortex, affecting both glucocorticoid and mineralocorticoid levels.

Pheochromocytoma

A tumor of the adrenal medulla chromaffin cells that produces excess catecholamines.

Diabetes Mellitus

A systemic metabolic disorder characterized by chronic hyperglycemia due to defects in insulin secretion, action, or both.

HbA1c

Glycated hemoglobin test that reflects the average plasma glucose levels over the preceding 8 to 12 weeks.

Graves Disease

The most common cause of hyperthyroidism, caused by Thyroid Stimulating Immunoglobulins (TSI) binding to $TSH$ receptors.

Hashimoto Thyroiditis

An autoimmune inflammatory disorder involving lymphocytic infiltration and destruction of the thyroid gland.

Metformin

A first-line biguanide insulin sensitizer that decreases hepatic gluconeogenesis and is used for Type 2 DM.

Levothyroxine ($T_4$)

The synthetic preparation of choice for thyroid replacement and suppression therapy due to its long half-life of 7 days.