Endocrine System

Overview of the Endocrine System

The endocrine system is a network of glands distributed throughout the body that regulate physiological processes by secreting hormones directly into the bloodstream. These hormones influence metabolism, growth, development, and homeostasis.

• Main glands: pituitary, thyroid, parathyroid, adrenal, pancreas (islets of Langerhans), gonads (ovaries and testes), and thymus.

• Function: Hormones released by these glands regulate metabolic activities, growth, and development.

Endocrine Glands and Their Hormones

Pituitary Gland (Hypophysis)

The pituitary gland, often called the "master gland," is a pea-sized structure at the base of the brain. It is divided into anterior and posterior lobes, each producing specific hormones that regulate other endocrine glands and body functions.

• Anterior Lobe Hormones:

  • GH (Growth Hormone): Regulates growth of tissues and bones.

  • ACTH (Adrenocorticotropic Hormone): Stimulates the adrenal cortex to produce corticosteroids.

  • TSH (Thyroid Stimulating Hormone): Stimulates the thyroid gland to produce thyroid hormones.

  • PRL (Prolactin): Stimulates milk production in the mammary glands.

• Posterior Lobe Hormones:

  • ADH (Antidiuretic Hormone): Promotes water reabsorption in the kidneys, reducing urine output.

  • Oxytocin: Stimulates uterine contractions during labor and milk ejection during breastfeeding.

Other Endocrine Glands and Hormones

• Islets of Langerhans (Pancreas): Secrete insulin (lowers blood glucose) and glucagon (raises blood glucose).

• Adrenal Medulla: Secretes epinephrine (adrenaline), which increases heart rate and respiration during stress.

Medical Terminology: Word Parts

Combining Forms

• aden/o, adrenal/o: adrenal glands

• endocrin/o: endocrine

• pituitar/o: pituitary gland

• thyr/o, thyroid/o: thyroid gland

Suffixes

• -drome: run, running (as in syndrome)

Disease and Disorder Terms

Terms Built from Word Parts

• Acromegaly: Enlargement of extremities due to excessive growth hormone.

• Adrenalitis: Inflammation of the adrenal glands.

• Hyperglycemia: Excessive sugar in the blood.

• Hypothyroidism: Deficient thyroid activity.

• Parathyroidoma: Tumor of a parathyroid gland.

Terms Not Built from Word Parts

• Addison Disease: Deficiency in adrenal cortex hormones.

• Cushing Syndrome: Excessive production of adrenal cortisol.

• Diabetes Mellitus (DM): Underactivity of insulin, resulting in hyperglycemia.

• Gigantism: Excessive growth hormone secretion during childhood.

• Graves Disease: Excessive thyroid hormone production (hyperthyroidism).

• Goiter: Enlargement of the thyroid gland.

• Metabolic Syndrome: Cluster of symptoms (S/S) increasing risk for diabetes mellitus.

• Tetany: Muscle spasms due to low calcium levels.

Surgical Terms

Terms Built from Word Parts

• Adrenalectomy: Excision of the adrenal gland.

• Pancreatectomy: Excision of the pancreas.

• Parathyroidectomy: Excision of a parathyroid gland.

• Thyroidectomy: Excision of the thyroid gland.

Diagnostic Terms

Terms Not Built from Word Parts

• Radioactive Iodine Uptake (RAIU): Nuclear medicine scan to visualize thyroid function.

• Thyroid Sonography: Ultrasound imaging of the thyroid gland.

• Fasting Blood Sugar (FBS): Measures blood glucose levels after fasting.

• Glycosylated Hemoglobin (HbA1C): Test to diagnose and monitor diabetes mellitus by measuring average blood glucose over several months.

• Thyroid-Stimulating Hormone (TSH) Test: Measures TSH levels to assess thyroid function.

Complementary Terms

Terms Built from Word Parts

• Adenopathy: Disease of a gland (often refers to lymph nodes but can include adrenal glands).

• Cortical: Pertaining to the cortex (outer layer of an organ).

• Endocrinology: Study of the endocrine system.

• Euglycemia: Normal blood glucose level.

• Polydipsia: Excessive thirst.

• Syndrome: Group of signs and symptoms occurring together, characteristic of a particular disease.

Terms Not Built from Word Parts

• Exophthalmos: Protruding eyeballs, often associated with Graves disease.

• Hormone: Chemical substance secreted by an endocrine gland that acts on target tissues.

• Metabolism: Chemical processes that occur within a living organism to maintain life.

Abbreviations Related to the Endocrine System

Examples and Applications

• Example: A patient with Graves disease may present with exophthalmos and elevated thyroid hormone levels.

• Example: Fasting blood sugar and HbA1C tests are commonly used to diagnose and monitor diabetes mellitus.

• Example: Adrenalectomy may be performed to remove a tumor from the adrenal gland.

Additional info: The endocrine system works closely with the nervous system to maintain homeostasis. Disorders of the endocrine system can have widespread effects due to the systemic action of hormones.