Chapter 13 - The Endocrine System (Medical Terms)

Functions of the Thyroid Gland

- One of the primary functions of the thyroid gland is to regulate the body's metabolism. - Thyroid secretions also influence growth and the functioning of the Nervous System.

Synthetic Thyroid Hormones

Are administered to replace lost thyroid function.

Hormones

Are chemical messengers that are secreted by endocrine glands and have specialized functions in regulating the activities of specific cells, organs, or both. Because the hormones are secreted directly into the bloodstream, they are able to reach cells and organs throughout the body. Blood, or urine, tests are used to measure hormone levelss.

Anabolic Steroids

Are chemically related to the male sex hormone testosterone. These have been used illegally by athletes to increase strength and muscle mass. Serious side effects of anabolic steroid use include liver damage, altered body chemistry, testicular shrinkage, and breast development in males, plus unpredictable mood swings and violence.

Pancreatic Islets

Are those parts of the pancreas that have endocrine functions.

Metabolism

Describes all of the processes involved in the body's use of nutrients, including the rate at which they are utilized.

Nonfunctioning Pituitary Tumors

Do not produce significant amounts of hormones.

Hormones Secreted by Fat Cells

Fat is not commonly thought of as an endocrine gland; however, research ahs revealed that fat cells do secrete at least one, and possible more, hormones that play an important role in the balance and health of the body.

Prolactinoma (Prolactin-Producing Adenoma)

Is a benign tumor of the pituitary gland that causes it to produce too much prolactin. In females, this overproduction causes infertility and changes in menstruation. In males it causes impotence.

Osteitis Fibrosa

Is a complication of hyperparathyroidism in which bone becomes softened and deformed, and may develop cysts. This condition can be caused by overproduction of parathyroid hormone or by parathyroid cancer.

Hypocrinism

Is a condition caused by a deficient secretion of any gland, especially an endocrine gland. Hypocrinism is the opposite of Hypercrinism.

Hypercrinism

Is a condition due to excessive secretion of any gland, especially an endocrine gland. Hypercrinism is the the opposite of Hypocrinism.

Hypopituitarism

Is a condition of reduced secretion due to the partial, or complete, loss of the function of the anterior lobe of the pituitary gland. Hypopituitarism is the opposite of Hyperpituitarism.

Cretinism

Is a congenital form of hypothyroidism. If treatment is not started soon after birth, cretinism causes arrested physical and mental development.

Thyroid-Stimulating Hormone Assay

Is a diagnostic test to measure the circulating blood level of thyroid-stimulating hormone. This test is used to detect abnormal thyroid activity resulting from excessive pituitary stimulation.

Pancreas

Is a feather-shaped organ located posterior to the stomach that functions as part of both the digestive and the endocrine systems.

Leptin

Is a hormone secreted by adipocytes (fat cells). - Leptin leaves the fat cells and travels in the bloodstream to brain centers. Here, it acts to control the balance of food intake and energy expenditure. - Leptin also affects female reproduction, immune function, and the function of many other hormones, including insulin.

Antithyroid Drug

Is a medication administered to slow the ability of the thyroid gland to produce thyroid hormones.

Diuretic

Is a medication that is administered to increase urine secretion.

Endocrinologist

Is a physician who specializes in diagnosing and treating diseases and malfunctions of the endocrine glands.

Thyroid Storm (Thyrotoxic Crisis)

Is a relatively rare, life-threatening condition caused by exaggerated hyperthyroidism. Patients experiencing a thyroid storm may complain a fever, chest pain, palpitations, shortness of breath, tremors, increased sweating, disorientation, and fatigue.

Pituitary Adenoma (Pituitary Tumor)

Is a slow-growing, benign tumor of the pituitary gland. The two types of these tumors are functioning and nonfunctioning pituitary tumors.

Adenoma

Is a small growing benign growth of glandular origin.

Infundibulum

Is a stalk-like structure.

Pitocin

Is a synthetic form of oxytocin that is administered to induce or speed up labor.

Human Growth Hormone (Recombinant GH)

Is a synthetic version of the growth hormone that is administered to stimulate growth when the natural supply of growth hormone is insufficient for normal development.

Pinealoma

Is a tumor of the pineal gland that can disrupt the production of melatonin. This tumor can also cause insomnia by disrupting the circadian cycle.

Acromegaly

Is abnormal enlargement of the extremities (hands and feet) that is caused by excessive secretion of growth hormone after puberty. Contrast with Gigntism.

Gigantism (Giantism)

Is abnormal overgrowth of the entire body that is caused by excessive secretion of the growth hormone before puberty. Contrast with Acromegaly.

Goiter (Thyromegaly)

Is an abnormal nonmalignant enlargement of the thyroid gland. This enlargement produces a swelling in the front of the neck. A simple goiter usually occurs when the thyroid gland is not able to produce enough thyroid hormone to meet the body's needs.

Exophthalmos

Is an abnormal protrusion of the eyeball out of the orbit.

Hashimoto's Thyroiditis (Chronic Lymphocytic Thyroiditis)

Is an autoimmune disease in which the body's own antibodies attack and destroy the cells of the thyroid gland.

Hyperthyroidism (Thyrotoxicosis)

Is an imbalance of metabolism caused by the overproduction of thyroid hormones. Symptoms include an increased metabolic rate, sweating, nervousness, and weight loss.

Thymitis

Is an inflammation of the thymus gland.

Pituitarism

Is any disorder of pituitary function.

Steroid

Is any one of a large number of hormone-like substances secreted by the endocrine glands or artificially produced as medications to relieve swelling and inflammation in conditions such as asthma.

Hypothyroidism (Underactive Thyroid)

Is caused by a deficiency of thyroid secretion. Symptoms include fatigue, depression, sensitivity to cold, and a decreased metabolic rate.

Hypoparathyroidism

Is caused by an insufficient or absent secretion of the parathyroid hormone. This condition causes hypocalcemia, and in severe cases, it leads to tetany.

Myxedema (Adult Hypothyroidism)

Is caused by extreme deficiency of thyroid secretion. Symptoms include swelling, particularly around the eyes and cheeks, fatigue, and a subnormal temperature.

Diabetes Insipidus

Is caused by insufficient production of the antidiuretic hormone or by the inability of the kidneys to respond appropriately to this hormone. When there is an insufficient quantity of ADH, too much fluid to be excreted by the kidneys. This causes extreme polydipsia (excessive thirst) and polyuria (excessive urination). If this problem is not controlled, it can become a very serious condition due to dehydration.

Primary Hyperparathyroidism

Is caused to a disorder of the parathyroid gland and it can lead to weakened bones and the formation of kidney stones. In 85 percent of people with primary hyperparathyroidism, a benign tumor known as an adenoma has formed on one of the parathyroid glands, causing it to become overactive.

Hypercalcemia

Is characterized by abnormally high concentrations of calcium circulating in the blood instead of being stored in the bones. This can lead to weakened bones and the formation of kidney stones. Hypercalcemia is the opposite of hypocalcemia.

Hypocalcemia

Is characterized by abnormally low levels of calcium in the blood. Hypocalcemia is the opposite of hypercalcemia.

Secondary Hyperparathyroidism

Is due to a disorder elsewhere in the body, such as kidney failure. Hyperparathyroidism is the opposite of hypoparathyroidism. when symptoms do appear, they are often mild and nonspecific, such as a feeling of weakness and fatigue, depression, or aches and pains. With more severe disease, a person may have a loss appetite, nausea, vomiting, constipation, confusion or impaired thinking and memory, and increased thirst and urination.

Thymus

Is located near the midline in the anterior portion of the thoracic cavity. It is posterior to (behind) the sternum and slightly superior to (above) the heart.

Hyperpituitarism

Is pathology resulting in the excessive secretion by the anterior lobe of the pituitary gland. Hyperpituitarism is the opposite of Hypopituitarism.

Chemical Thyroidectomy (Radioactive Iodine Therapy)

Is the administration of radioactive iodine to destroy thyroid cells. This procedure, which disables at least part of the thyroid gland, is used to treat chronic hyperthyroid disorders such as Grave's Disease.

Hyperparathyroidism

Is the overproduction of the parathyroid hormone.

Lobectomy

Is the surgical removal of one lobe of the thyroid gland. This term is also used to describe the removal of a lobe of the liver, brain, or lung.

Pinealectomy

Is the surgical removal of the pineal gland.

Thymectomy

Is the surgical removal of the thymus gland.

Pineal Gland (Pineal Body)

Is very small endocrine gland that is located in the central portion of the brain.

Functioning Pituitary Tumors

Often produce hormones in large and unregulated amounts.

Circadian Cycle

Refers to the biological functions that occur within a 24-hour period.

Calcitonin (CAL)

Source : Thyroid Gland. Works with the Parathyroid Hormone to regulate calcium levels in the blood and tissues.

Aldosterone (ALD)

Source: Adrenal Cortex Aids in regulating the levels of salt and water in the body.

Cortisol (Hydrocortisone)

Source: Adrenal Cortex Regulates the metabolism of carbohydrates, fats, and proteins in the body. Also has an anti-inflammatory action. Has an anti-inflammatory action, and it regulates the metabolism of carbohydrates, fats, and proteins in the body.

Androgens

Source: Adrenal Cortex and Gonads Influence sex-related characteristics. Are hormones that influence sex-related characteristics. Normally, in adults the production of androgens in the adrenal cortex is minimal; instead, these hormones are produced in the male and female gonads.

Norepinephrine

Source: Adrenal Medulla Stimulates the Sympathetic Nervous System. Is both a hormone and a neurohormone. It is released as a neurohormone by the sympathetic nervous system and as a hormone by the adrenal medulla. It plays an important role in the "fight-or-flight response" by raising blood pressure, strengthening the heartbeat, and stimulating muscle contractions.

Epinephrine (Epi, EPI, Adrenaline)

Source: Adrenal Medulla Stimulates the sympathetic nervous system in response to stress or other stimuli. It makes the heart beat faster and can raise blood pressure. It also helps the liver release glucose (sugar) and limits the release of insulin.

Progesterone

Source: Ovaries Completes preparation of the uterus for possible pregnancy.

Estrogen (E)

Source: Ovaries. Develops and maintain the female secondary sex characteristics and regulates the menstrual cycle.

Glucagon (GCG)

Source: Pancreatic Islets (Alpha Cells) Increases the level of glucose in the bloodstream.

Insulin

Source: Pancreatic Islets (Beta Cells) Regulates the transport of glucose to body cells and stimulates the conversion of excess glucose to glycogen for storage. Is the hormone secreted by the beat cells of the pancreatic islets in response to high blood sugar levels. It functions in two ways. First, Insulin allows glucose to enter the cells for use as energy. When additional glucose is not needed, insulin stimulates the liver to convert glucose into glycogen for storage.

Parathyroid Hormone (PTH)

Source: Parathyroid Glands Works with calcitonin to regulate calcium levels in the blood and tissues.

Melatonin

Source: Pineal Gland Influences the sleep-wakefulness cycles and portions of the circadian cycles.

Luteinizing Hormone (LH)

Source: Pituitary Gland In the female, stimulates ovulation. In the male, stimulates testosterone secretion.

Follicle-Stimulating Hormone (FSH)

Source: Pituitary Gland In the female, stimulates the secretion of estrogen and the growth of ova (eggs). In the male, stimulates the production of sperm in the testicles.

Melanocyte-Stimulating Hormone (MSH)

Source: Pituitary Gland Increases the production of melanin in melanocytes of the skin, thereby causing darkening the pigmentation of the skin.

Growth Hormone (GH) a.k.a Somatotropic Hormone

Source: Pituitary Gland Regulates the growth of bone, muscle, and other body tissues.

Lactogenic Hormone (LTH) a.k.a Prolactin

Source: Pituitary Gland Stimulates and maintains the secretion of breast milk.

Interstitial Cell-Stimulating Hormone (ICSH)

Source: Pituitary Gland Stimulates ovulation in the female. Stimulates the secretion of testosterone in the male.

Adrenocorticotropic Hormone (ACTH)

Source: Pituitary Gland Stimulates the growth and secretions of the adrenal cortex.

Thyroid-Stimulating Hormone (TSH)

Source: Pituitary Gland Stimulates the secretion of hormones by the thyroid gland.

Oxytocin (OXT)

Source: Pituitary Gland Stimulates uterine contractions during childbirth. It also causes milk to flow from the mammary glands after childbirth.

Human Chorionic Gonadotropin (HC)

Source: Placenta stimulates the secretion of the hormones required to maintain pregnancy.

Antidiuretic Hormone (ADH)

Source: Secreted by the Hypothalamus, then stored and released from the pituitary gland. Helps control blood pressure by reducing the amount of water that is excreted. Maintains the water balance within the body by promoting the reabsorption of water through the kidneys.

Testosterone

Source: Testicles Stimulates the development of male secondary sex characteristics.

Thymosin

Source: Thymus Plays an important role in the immune system. Stimulates the maturation of lymphocytes into T cells of the immune system. These mature cells are important in coordinating immune defenses.

Thyroxine (T4) and Triiodothyronine (T3)

Source: Thyroid Gland. Regulate the rate of metabolism.

Functions of the Pancreatic Islets

The Endocrine functions of these islets are to control blood sugar levels and glucose metabolism throughout the body.

Thyroid Gland

The butterfly-shaped thyroid gland lies on the other side of the larynx, just below the thyroid cartilage.

Parathyroid Glands

The four parathyroid glands, each of which is about the size of a grain of rice, are embedded in the posterior surface of the thyroid gland.

Functions of the Pineal Gland

The pineal gland, also known as the pineal body, influences the sleep-wakefulness cycle.

Functions of the Endocrine System

The primary function of the endocrine system is to produce hormones that work together to maintain homeostasis (constant internal environment) throughout the body systems.

Functions of the Parathyroid Glands

The primary function of the parathyroid glands to regulate calcium levels throughout the body. These calcium levels are important to the smooth functioning of the muscular and nervous systems.

Functions of the Pituitary Gland

The primary function of the pituitary gland is to secrete hormones that control the activity of other endocrine glands. The pituitary acts in response to stimuli from the hypothalamus. This creates a system of checks and balances to maintain an appropriate blood level of each hormone.

Thyroxine and Triiodothyronine

The rate of metabolism is influenced by these hormones. The rate of secretion of these hormones is controlled by the thyroid-stimulating hormone produced by the anterior lobe of the pituitary gland.

Functions of the Thymus

The thymus functions as part of the endocrine system by secreting a hormone that functions s part of the immune system.

Structures of the Endocrine System

There are 13 major glands of the Endocrine System: - 1 Pituitary Gland. - 1 Pineal Gland. - 1 Thyroid Gland. - 4 Parathyroid Glands. - 1 Thymus. - 1 Pancreas (Pancreatic Islets) - 2 Adrenal Glands. - 2 Gonads (Ovaries in females, Testes in males).

Specialized Types of Hormones

There are several specialized types of hormones that do not fit the tradition hormone definition.

Neurohormones

Unlike the hormones, which are secreted by endocrine glands, Neurohormones are secreted by specialized cells of the brain. Although produced in the brain, they are able to affect cells throughout distant parts of the body.

Pituitary Gland

Which is composed of anterior and posterior lobes, hangs from the infundibulum below the hypothalamus, which is part of the brain.

Calcitonin

Which is secreted by cells of the thyroid gland, works with the parathyroid hormone to regulate the calcium levels in the blood and tissues. Calcitonin decreases blood levels by moving calcium into storage in the bones and teeth. Compare with the function of the Parathyroid Hormone.

Parathyroidectomy

Which is the surgical removal of one or more of the parathyroid glands, is performed to control hyperparathyroidism.

Thyroid Scan

Which measures thyroid function, is a form of nuclear medicine.

Parathyroid Hormone

Works with the hormone calcitonin that is secreted by the thyroid gland. Together, they regulate the calcium levels in the blood and tissues. The parathyroid hormone increases calcium levels in the blood by mobilizing the release of calcium from storage in the bones and teeth. Compare with the function of the calcitonin.

Endocrinopathy

is any disease caused by a disorder of the endocrine system.

Tetany

is the condition of periodic, painful muscle spasms and tremors. Hypoparathyroidism is the opposite of hyperparathyroidism.

Graves' Disease

which is an autoimmune disorder that is caused by hyperthyroidism, is characterized by goiter and/or exophthalmos.