IX Glossary
Acromegaly: A disorder that results in the thickening of bones in the face, hands, and feet in response to excessive levels of hGH in individuals who have stopped growing. (Chapter 9.3)
Addison’s disease: A disorder in which the adrenal glands do not produce enough cortisol; also called primary adrenal insufficiency. (Chapter 9.4)
Adrenal cortex: The outer layer of the adrenal glands that produces steroid hormones and is part of the hypothalamic-pituitary-adrenal (HPA) axis. (Chapter 9.3)
Adrenal glands: Wedges of tissue attached to the top of each kidney that produce various hormones. (Chapter 9.3)
Adrenal medulla: Neuroendocrine tissue that is an extension of the autonomic nervous system. (Chapter 9.3)
Adrenocorticotropic hormone (ACTH): A hormone from the anterior pituitary that stimulates the adrenal cortex to release corticosteroid hormones like cortisol; also called corticotropin. (Chapter 9.3)
Aldosterone: The main mineralocorticoid hormone that helps balance sodium and potassium levels and controls blood pressure and volume. (Chapter 9.3)
Alpha cells: Secrete the hormone glucagon, which increases blood glucose. Low blood glucose levels stimulate its release. (Chapter 9.3)
Antagonistic effect: When two hormones have opposing effects. (Chapter 9.3)
Antidiuretic hormone (ADH): A hormone released by the posterior pituitary that helps the body retain water when blood osmolality is high, such as during dehydration. (Chapter 9.3)
Beta cells: Secrete the hormone insulin, which decreases blood glucose levels. Elevated blood glucose levels stimulate the release of insulin. (Chapter 9.3)
Blood osmolality: The concentration of dissolved substances (solutes) in the blood, which can change due to diet, illness, medications, or other factors. (Chapter 9.3)
Calcitonin: A hormone from the thyroid’s parafollicular (C) cells that lowers blood calcium levels when they rise too high. (Chapter 9.3)
Calcitriol: The active form of vitamin D3 produced in the kidneys under the influence of parathyroid hormone (PTH); it helps the intestines absorb more calcium from food. (Chapter 9.3)
Cortisol: The main glucocorticoid hormone that helps the body respond to stress by breaking down stored nutrients for energy and slowing tissue building. (Chapter 9.3)
Cushing’s disease: A disorder caused by elevated levels of cortisol from the adrenal glands, leading to a wide range of symptoms. (Chapter 9.4)
Delta cells: Secrete the peptide hormone somatostatin. Somatostatin is also released by the hypothalamus (as GHIH), the stomach, and the intestines. It inhibits the release of both glucagon and insulin. (Chapter 9.3)
Diabetes mellitus: A disorder of the endocrine system where the body has trouble making insulin or using it properly, which affects how cells take in and use glucose (sugar) from the blood. (Chapter 9.4)
Downregulation: A process where target cells reduce the number of hormone receptors to decrease their response to high hormone levels. (Chapter 9.3)
Endocrine glands: Primary structural and functional units of the endocrine system. (Chapter 9.3)
Endocrine surgeons: Treat endocrine disease through the removal, or resection, of the affected endocrine gland. (Chapter 9.5)
Endocrinologists: Medical doctors who specialize in treating diseases associated with hormonal systems. (Chapter 9.5)
Endocrinology: A specialty in the field of medicine that focuses on the treatment of endocrine system disorders. (Chapter 9.5)
Epinephrine: A hormone from the adrenal medulla that is produced in large amounts and helps the body respond quickly to stress; also called adrenaline. (Chapter 9.3)
Estrogens: Hormones produced by the ovaries, including estradiol, estriol, and estrone, that regulate the reproductive system, menstrual cycle, female secondary sex traits, and pregnancy. (Chapter 9.3)
Exocrine glands: Release their secretions through ducts. (Chapter 9.3)
Exophthalmos: A condition in which the eyes bulge outward, often associated with hyperthyroidism, especially Graves’ disease. (Chapter 9.4)
Fat-soluble: Hormones derived from lipids. (Chapter 9.3)
Follicle-stimulating hormone (FSH): A gonadotropin that promotes the production and development of sex cells (ova in females and sperm in males). (Chapter 9.3)
Gigantism: A disorder in children that is caused by the secretion of abnormally large amounts of hGH, resulting in excessive growth. (Chapter 9.3)
Glucagon: A hormone secreted by alpha cells of the pancreas in response to low blood glucose levels. It raises blood glucose by triggering the release of stored glucose from the liver. (Chapter 9.3)
Glucocorticoids: Hormones from the adrenal cortex that help regulate glucose (sugar) metabolism and the body’s response to stress. (Chapter 9.3)
Glycogen: A stored form of glucose found in the liver and muscles, used for energy when blood glucose levels are low. (Chapter 9.3)
Glycogenolysis: The process of converting stored glycogen in the liver back into glucose, which is then released into the blood. (Chapter 9.3)
Gluconeogenesis: The process by which the liver converts amino acids from the blood into glucose. (Chapter 9.3)
Glycolysis: The process of breaking down glucose to produce ATP (energy), stimulated by insulin to help lower blood glucose levels. (Chapter 9.3)
Goiter: An abnormal enlargement of the thyroid gland, often caused by iodine deficiency or thyroid dysfunction. (Chapter 9.4)
Gonadotropins: Hormones from the anterior pituitary that control the ovaries in females and testes in males, regulating reproductive functions. (Chapter 9.3)
Graves’ disease: An autoimmune disease in which antibodies overstimulate the thyroid gland. (Chapter 9.4)
Hormone receptor: A protein located either inside the cell or within or on the cell membrane that receives a hormone’s message. (Chapter 9.3)
Hormones: A chemical messenger that travels in the blood to target cells and causes a response in the body. (Chapter 9.1)
Human growth hormone (hGH): A protein hormone from the anterior pituitary that supports growth by promoting protein synthesis and tissue building; Also called somatotropin. (Chapter 9.3)
Hyperglycemia: A condition in which blood glucose levels are higher than normal; it is used to diagnose diabetes. (Chapter 9.4)
Hyperparathyroidism: A disorder caused by an overproduction of PTH that results in excessive calcium reabsorption from bone. (Chapter 9.4)
Hyperthyroidism: An abnormal, elevated level of thyroid hormone in the blood. (Chapter 9.4)
Hypoparathyroidism: Abnormally low blood calcium levels may be caused by parathyroid hormone deficiency. (Chapter 9.4)
Hypothalamus–pituitary complex: The “command center” of the endocrine system. (Chapter 9.3)
Hypothyroidism: A clinically abnormal, low level of thyroid hormone in the blood. (Chapter 9.4)
Infundibulum (pituitary stalk): A thin connection between the hypothalamus and the pituitary gland that allows hormones and signals to pass between them. (Chapter 9.3)
Inhibiting hormones: Slows or stops the secretion of hormones from the anterior pituitary gland. (Chapter 9.3)
Insulin: A hormone secreted by beta cells of the pancreas that decreases blood glucose levels. Elevated blood glucose levels stimulate its release. (Chapter 9.3)
Insulin-like growth factors (IGFs): Hormones released by the liver and other tissues in response to growth hormone; they help promote cell growth and tissue repair. (Chapter 9.3)
Luteinizing hormone (LH): A gonadotropin that triggers ovulation in females and stimulates testosterone production in males. (Chapter 9.3)
Melanocyte-stimulating Hormone (MSH): A hormone produced by cells between the pituitary lobes that helps the skin make melanin in response to UV light. (Chapter 9.3)
Melatonin: A hormone produced by the pineal gland that helps regulate the sleep-wake cycle. (Chapter 9.3)
Mineralocorticoids: Hormones produced by the adrenal cortex that regulate minerals like sodium and potassium in the body. (Chapter 9.3)
Negative feedback loops: The original stimulus is reduced or stopped. (Chapter 9.3)
Neuropathy: Loss of sensation caused by nerve damage, often occurring in the hands and feet due to reduced blood flow from blood vessel damage. (Chapter 9.4)
Norepinephrine: A hormone from the adrenal medulla that works with epinephrine to prepare the body for stress but is produced in smaller amounts; also called noradrenaline. (Chapter 9.3)
Osmoreceptors: Specialized cells in the hypothalamus that detect changes in blood osmolality by sensing solute levels like sodium. (Chapter 9.3)
Oxytocin: A hormone that stimulates uterine contractions and cervix dilation to help with childbirth. (Chapter 9.3)
Pancreas: A long, thin organ located mostly behind the lower part of the stomach that produces hormones and digestive enzymes. (Chapter 9.3)
Pancreatic islets: Clusters of cells in the pancreas that produce hormones like glucagon, insulin, somatostatin, and pancreatic polypeptide. (Chapter 9.3)
Parathyroid glands: Tiny, round structures usually found embedded in the posterior surface of the thyroid gland. (Chapter 9.3)
Parathyroid hormone (PTH): The major hormone responsible for increasing blood calcium levels. (Chapter 9.3)
Permissive effect: The presence of one hormone enables another hormone to act. (Chapter 9.3)
Pineal gland: A small gland in the brain below and behind the thalamus that produces melatonin, a hormone involved in regulating sleep. (Chapter 9.3)
Pituitary dwarfism: A disorder where abnormally low levels of hGH in children can cause growth impairment. (Chapter 9.3)
Pituitary gland: A pea-sized organ suspended from a stem called the infundibulum (or pituitary stalk); also known as the hypophysis. (Chapter 9.3)
Positive feedback loops: Amplify or exaggerate the original stimulus. (Chapter 9.3)
PP cells: Secrete pancreatic polypeptide hormone. It is thought to play a role in appetite and the regulation of pancreatic exocrine and endocrine secretions. (Chapter 9.3)
Primary adrenal insufficiency: A disorder in which the adrenal glands do not produce enough cortisol; also called Addison’s disease. (Chapter 9.4)
Progesterone: A hormone from the ovaries that helps regulate the menstrual cycle and supports pregnancy preparation and maintenance. (Chapter 9.3)
Prolactin (PRL): Promotes lactation (milk production). (Chapter 9.3)
Receptor: A protein located either inside the cell or within the cell’s membrane that binds a hormone. (Chapter 9.3)
Releasing hormones: Stimulates the secretion of hormones from the anterior pituitary gland. (Chapter 9.3)
Synergistic effect: When two hormones with similar effects produce an amplified or bigger response together. (Chapter 9.3)
Target cells: A cell that has specific receptors for a hormone and responds when the hormone binds to it. (Chapter 9.1, Chapter 9.3)
Testosterone: The main hormone produced by the testes that supports sperm development and causes male secondary sex traits like a deeper voice and muscle growth. (Chapter 9.3)
Thyroid gland: A butterfly-shaped organ in the neck, located in front of the trachea and below the larynx. (Chapter 9.3)
Thyroid-stimulating hormone (TSH): A hormone from the anterior pituitary that signals the thyroid gland to release thyroid hormones; also called thyrotropin. (Chapter 9.3)
Thyroxine (T4): A thyroid hormone with four iodine atoms that regulates metabolism and is converted into the active form, T3. (Chapter 9.3)
Triiodothyronine (T3): A thyroid hormone with three iodine atoms that helps regulate metabolism. (Chapter 9.3)
Type 1 diabetes mellitus: An autoimmune disease that destroys the pancreas’s beta cells, preventing insulin production. It accounts for less than 5% of all diabetes cases. (Chapter 9.4)
Type 2 diabetes mellitus: A condition accounting for about 95% of all diabetes cases, often linked to overweight or obesity and lifestyle factors like poor diet and low physical activity. (Chapter 9.4)
Upregulation: A process where target cells increase the number of hormone receptors to increase their sensitivity to hormones present. (Chapter 9.3)
Water-soluble hormones: Hormones derived from amino acids include amines, peptides, and proteins. (Chapter 9.3)
