You may come across many medical terms as you are reading information about the endocrine system or speaking to your endocrinologist about a condition. Below are brief and simple definitions of almost any word you read or hear related to endocrinology, so you can focus on understanding your condition and its treatment.
The abdomen is the part of the body between the chest and the pelvis. The abdomen contains all the digestive organs, including the stomach, small and large intestines, pancreas, liver and gallbladder. The abdomen also contains the kidneys and spleen.
The pelvic cavity is the body cavity (a hollow or space) that is bounded by the bones of the pelvis and includes the reproductive organs, the bladder, part of the colon and the rectum.
The adrenal glands make hormones that help control the way the body uses food, the levels of minerals such as sodium and potassium in the blood, heart rate, blood pressure and other functions involved in stress reactions.
The adrenal cortex is the outside part of the adrenal gland. It makes cortisol that controls carbohydrate and fat metabolism and the body’s response to stress. It also produces aldosterone, which regulates salt and water balance in the body. Additionally, it produces sex steroids.
The adrenal medulla is the inner part of the adrenal gland that produces the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine).
Adrenaline, also known as epinephrine, is responsible for preparing the body for “fight or flight." It affects the size of blood vessels throughout the body, such as the heart, brain, skin and muscles. Adrenaline is produced under stressful or exciting situations. When released, it causes a rapid pulse, higher blood pressure, shakiness, sweating, dilated pupils, and pallor or blanching of the skin (when the skin becomes white or pale).
Anatomy is the study of the human body by observation or examination.
Anterior pituitary is the front of the pituitary gland that produces and secretes several hormones, including growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and melanocyte-stimulating hormone (MSH).
An artery is a blood vessel that moves blood away from the heart.
Autonomic nervous system
The autonomic nervous system is the part of the nervous system that regulates many organ systems, including controlling your heartbeat and digestion. Blood pressure problems, heart problems, trouble with breathing and swallowing and erectile dysfunction in men may occur when the autonomic nervous system is not working properly.
Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps blood.
The brain is the center of the human nervous system located within the skull. It receives, organizes and distributes information for the body. It controls your walking, talking, swallowing, breathing, taste, smell and all other voluntary and involuntary actions.
C-peptide is a substance made by the pancreas as a result of insulin production. The C-peptide test is a tool a doctor can use to find out how much insulin is being produced in the body and can be used in the diagnosis of diabetes mellitus and in the diagnosis of rare pancreas tumors secreting excess insulin (insulinomas).
Calcium is an essential element, is a vital source for bone strength and plays an important role in the body’s inflammatory response. Almost all the body’s calcium is stored in the bones and teeth.
Central nervous system
The central nervous system (CNS) consists of the brain, including the cranial nerves, and the spinal cord. The brain and spinal cord serve as the main processing center for the entire nervous system and control all the functions of your body.
Circadian rhythms are physical, mental and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness of an individual’s day.
The circulatory system is made up of your heart and blood vessels providing a continuous supply of blood flowing through the body. It helps tissues get oxygen and nutrients and also helps them remove waste products.
The cortex is the outer layer of any organ.
Cortisol is a stress hormone produced by the adrenal cortex.
A diabetologist is a physician that diagnoses and treats people who have diabetes.
Diabetes mellitus, or diabetes, is an endocrine disease in which your blood glucose (sugar) is too high. In type 1 diabetes, the pancreas no longer produces insulin. In type 2 diabetes, the body doesn’t respond to insulin properly, and later in the disease these patients often don’t make enough insulin.
Diabetic neuropathy is nerve damage as a result of poorly controlled diabetes. It may lead to a loss of feeling, numbness, tingling or burning pain in the hands, arms, toes and feet.
Diabetic retinopathy is a condition caused by poorly controlled diabetes that affects the eyes. It results from damage to small blood vessels that are in the retina. It can cause vision problems and eventually lead to blindness.
Diagnosis is the act of determining what disease or condition a person has based on signs, symptoms and tests.
DPP-4 inhibitor is a class of oral medication used to treat type 2 diabetes. It lowers blood glucose by blocking an enzyme called DPP-4, which destroys a hormone called incretin. Incretins help the body make more insulin only when it’s needed and decrease glucose production by the liver when it’s not needed.
The endocrine system consists of the glands that produce and release different types of hormones directly into the bloodstream. It regulates the body’s functions such as metabolism, mood, tissue function, growth and development.
Endocrinology is a medical subspecialty that studies the glands and hormones of the body.
An endocrinologist is a physician who specializes in endocrinology.
Enzymes are proteins that cause specific chemical reactions that are important to the body’s functions.
Estrogen is a hormone that is produced primarily by the ovaries and is important for sexual and reproductive development, mainly in women. Estrogen levels change naturally over the female lifespan, reaching adult levels with the onset of puberty and decreasing during middle age until the onset of menopause.
Exocrine glands are glands that secrete their products directly into ducts. From the duct, they flow either into the bloodstream or from one cell to another cell. Examples include sweat glands and salivary glands.
A follicle-stimulating hormone (FSH) is a hormone released from the anterior pituitary. In females, FSH activates the maturation of ovarian follicles. In males, FSH is critical for sperm production and supports sperm cell maturation.
A gamete is a germ cell that combines with another cell during conception.
A gland is an organ that produces and releases substances that perform a specific body function. Endocrine glands secrete hormones directly into the bloodstream and can act on other endocrine glands, and exocrine glands secrete their products through ducts.
Glucocorticoid is a type of steroid hormone that mainly affects the metabolism of carbohydrates, is important in the body’s use of energy and has anti-inflammatory actions.
Glucose is the main source of energy or fuel for all the body’s functions. Although the body gets most of its glucose from carbohydrates in food, glucose can also be made from protein and fat.
Enlargement of the thyroid gland caused by decreased production of T3 (triiodothyronine) and T4 (thyroxine).
Gonads are the main reproductive organs. In males, the gonads are the testes. In females, they are the ovaries.
Gonadotropins are hormones that stimulate the gonads, which are the ovaries in females and testes in males.
Graves’ disease is an autoimmune thyroid disease. This disease is associated with an overactive thyroid gland which produces excess quantities of thyroid hormones.
Growth hormone is a hormone produced by the pituitary gland that fuels childhood growth and helps maintain tissues and organs throughout life.
Gynecomastia is the enlargement of breast tissue in males. Breast enlargement is common in men and boys at various stages of development, but also may be associated with certain medical conditions.
Hashimoto’s disease is an autoimmune thyroid disease and is the most common type of thyroid disease in the United States. Hashimoto’s disease is associated with inflammation of the thyroid. It is characterized by the production of immune cells and autoantibodies of the body’s immune system, which can damage thyroid cells and interfere with their ability to make thyroid hormones, leading to an underactive thyroid gland.
The heart is the muscle that pumps blood throughout the blood vessels. The heart has four chambers and is located in the chest behind the breastbone.
The heart rate is the number of times the heart beats in a minute.
Hirsutism is a condition of unwanted male-pattern hair growth in women. It causes excessive amounts of coarse and pigmented hair on body areas where men typically grow hair, such as the face, chest, abdomen and back.
A hormone is a chemical messenger released by a cell that transports a signal to other cells of the body.
Hyperglycemia is an elevation of blood glucose (sugar) that is above normal levels.
Hyperthyroidism is a type of thyroid disease caused by an overactive thyroid gland that is associated with excessive amounts of thyroid hormone. It causes an increase in the body's metabolism and can cause a variety of symptoms, such as racing heart rate, tremors, weight loss and insomnia.
Hypoglycemia is low blood sugar.
The hypothalamus is located just above the brain stem. It serves as the link between the endocrine system and the nervous system by communicating with the pituitary gland. It controls the pituitary gland by increasing or decreasing the release of hormones. It activates and controls involuntary functions such as body temperature, hunger and thirst.
Hypothyroidism is a condition caused by an underactive thyroid that doesn't produce enough thyroid hormones. It causes a decrease in the body's metabolism and can cause a variety of symptoms, such as fatigue, sleepiness, weight gain and constipation.
Immune means the presence of antibodies or lymphocytes that protect your body from infections and diseases.
The immune system is a complex network of interacting cells (lymphocytes), cell products and cell-forming tissues that protect the body from pathogens and other foreign substances. The immune system also destroys infected and malignant cells and removes cellular debris. It protects you from infections and diseases.
Insulin is a natural hormone made by the pancreas that controls the level of glucose (sugar) in the blood. If insulin is not made by the pancreas or the body does not respond to it properly, it leads to a disease called diabetes.
The kidneys, located on each side of the body, are organs that receive and filter waste products, minerals and water from your blood. The kidneys’ filtering of water maintains a stable balance of electrolytes in the blood. The kidneys filter medications and make substances that help control blood pressure and regulate the formation of red blood cells.
A lobe is a portion of an organ or a gland.
Luteinizing hormone is the hormone that stimulates ovulation and is involved in the production of estrogen and some androgens. This hormone also stimulates the production of testosterone by the testes in the male. It is important in sexual reproduction.
Luteinizing hormone-releasing hormone, or gonadotropin-releasing hormone
Luteinizing hormone-releasing hormone (LHRH), also known as gonadotropin-releasing hormone (GnRH), helps to control the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland. GnRH is synthesized and released from the hypothalamus.
The medulla is the inner core of certain organs or body structures.
Melatonin is a hormone secreted by the pineal gland that helps control your sleep and wake cycles.
Menarche is the time in a woman’s life when menstruation first begins. During this time, menstruation may be irregular and unpredictable.
Menopause is a time in a woman’s life when menstrual periods permanently stop.
Menstruation is the periodic blood that flows as a discharge from the uterus. It occurs in the absence of pregnancy when the uterus sheds its lining.
Metabolism comprises all of the chemical and physical processes in the body necessary for life. Processes include breaking down food for energy and producing substances to sustain life.
Muscle is the tissue of the body that primarily functions as a source of power. There are three types of muscle in the body: skeletal, which is responsible for moving extremities (limbs, hands and feet) and external areas of the body; cardiac, which is the muscle found in the heart; and smooth muscle, which is found in the walls of arteries, lungs and intestines.
The neck is the part of the body joining the head to the shoulders. The thyroid is located in the neck.
Neuroendocrine integration is a process that unites and coordinates the brain with the endocrine system.
An organ is a relatively independent part of the body that carries out one or more special functions. Examples of organs include the eyes, ears, heart, lungs and liver.
Osteoporosis is a condition marked by weak and brittle bones. If you have osteoporosis, you are more likely to fracture your bones and for many adults a fracture is the initial presentation of osteoporosis.
Oxytocin is a hormone that causes the uterus to contract during labor, which allows women to give birth. After birth it stimulates the nipples to make breastfeeding easier.
The pancreas is a gland near the stomach that helps break down food. It also secretes hormones that help control blood glucose (sugar) levels. If the pancreas does not work properly, it can lead to a disease called diabetes.
The parathyroid glands are four glands located behind each corner of the thyroid that regulate calcium levels in the body by releasing a hormone called parathyroid hormone.
The parathyroid hormone is made by the parathyroid glands. It is responsible for maintaining balance of calcium and phosphorus levels in the body by acting on bones and the kidneys.
Pediatrics is the branch of medicine that focuses on children.
Pineal gland (also called the pineal body) is a small endocrine gland that produces melatonin, a hormone that affects the wake and sleep patterns and seasonal functions. It is located near the center of the brain and shaped like a tiny pinecone.
The pituitary gland is an endocrine gland that secretes nine hormones that regulate aspects of your body’s metabolism. This gland has two components, the anterior pituitary secreting growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and melanocyte-stimulating hormone (MSH), and the posterior pituitary, secreting anti-diuretic hormone (ADH) and oxytocin.
Polycystic ovary syndrome
Polycystic ovary syndrome (PCOS) is a hormonal disorder affecting roughly 1 in 10 women of reproductive age. For most women with PCOS, the ovaries are enlarged and contain numerous small cysts (abnormal structures containing fluid) located along the outer edge of each ovary. The name of the condition (polycystic) comes from this appearance of the ovaries.
The posterior pituitary is one of the two lobes of the pituitary gland. It stores and secretes oxytocin and anti-diuretic hormone (ADH, or vasopressin) directly into the circulation. These hormones are involved in uterine contractions and managing levels of water in the blood, respectively.
Prediabetes is a condition in which blood sugar levels are higher than normal but are not elevated enough to qualify for the diagnosis of diabetes.
Progesterone is a female hormone that prepares the uterus to receive and sustain fertilized eggs.
Prolactin is a hormone secreted by the pituitary gland that helps with the development of mammary glands within the breast tissues and stimulates lactation, which is the production of milk. Abnormally high prolactin (hyperprolactinemia) can delay puberty, interfere with ovulation in women, decrease libido in men and decrease fertility. Hyperprolactinemia can occur in several physiologic conditions such as pregnancy and stress, due to medications, or due to a benign tumor in the pituitary gland called a prolactinoma.
Pubic symphysis, or symphysis pubis, is a joint composed of cartilage that unites the left and right pubic bones of the pelvis.
Renin-angiotensin system is a hormone system that regulates blood pressure and fluid balance in the body. It relies on the function of the kidneys.
The retroperitoneal space is located behind the abdominal lining (peritoneum). It includes the pancreas, kidneys, ureters and adrenal glands.
The scrotum is a pouch that contains the testes and parts of the spermatic cords in males.
Somatostatin is a hormone released by the hypothalamus and also produced in the pancreas. It has actions on the anterior pituitary gland and the gastrointestinal system, including the pancreas. It regulates endocrine and nervous system function by stopping the secretion of several other hormones such as growth hormone, insulin and gastrin.
Sperm is the male gamete or sex cell that is involved in fertilization (creating what will eventually be the fetus).
Steroids are a large group of chemical substances that are classified by a specific structure. Steroids include drugs used to relieve swelling and inflammation, such as prednisone, cortisone, vitamin D and some sex hormones, such as testosterone and estradiol.
The stomach is a digestive organ that is in the upper abdomen, under the ribs. The upper part of the stomach connects to the esophagus, and the lower part leads into the small intestine. The stomach is responsible for digesting foods through its acidic fluid and enzymes.
Stress is a physical, mental or emotional factor that causes bodily or mental tension.
The testes are the male sex glands located behind the penis in a pouch of skin called the scrotum. The testes produce and store sperm, and produce hormones called androgens, primarily testosterone.
Testosterone is a male sex hormone that is produced by the testes and is responsible for male growth and development.
The thalamus is the part of the brain that relays sensory and motor signals to the cerebral cortex (outer layer of the brain) and regulates consciousness, sleep and alertness.
Thermostat is a device that monitors temperature and automatically maintains it at certain levels. In humans, the tiny part of the brain called the hypothalamus, which is located behind the eyes, serves as the thermostat. It can warm the body by causing it to shiver and cool the body by causing it to sweat. The hypothalamus also regulates hunger, thirst, sex drive and other bodily activities.
The thyroid is a butterfly-shaped gland in the middle of the neck that produces two hormones, triiodothyronine (T3) and thyroxine (T4). These hormones are responsible for influencing the body’s metabolism, growth, development and temperature.
T3 (triiodothyronine) and T4 (thyroxine) are the hormones produced by the thyroid gland under stimulation by the pituitary gland. A deficiency of iodine (an essential mineral) leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as goiter.
Thyroiditis is inflammation of the thyroid gland.
Thyroid-stimulating hormone (TSH) is a hormone released by the pituitary gland that stimulates the thyroid. TSH levels in your bloodstream rise or fall depending on whether enough thyroid hormone is produced to meet your body’s needs. Higher levels of TSH prompt the thyroid to produce more thyroid hormone. Conversely, low TSH levels signal the thyroid to slow down production. TSH levels are tested and used in the diagnosis of thyroid disease.
The uterus is a hollow, pear-shaped organ that is located in a woman's lower abdomen, between the bladder and the rectum. It stores, nourishes and develops the fetus until it is ready to be born.
Vasopressin, also known as anti-diuretic hormone (ADH), is a hormone produced by the posterior pituitary gland. It can cause less frequent urination and cause the body to retain water.