endocrine

adrenal

two adrenal glands sit atop each kidney; each consists of two portions: the central region or adrenal medulla and the outer region or adrenal cortex. The adrenal cortex is the largest portion of the gland, and it secretes three types of steroid hormones called corticosteroids. Each has different functions:

. Glucocorticoids

affect glucose metabolism and maintain blood glucose levels

Mineralocorticoids

are involved in balance of electrolytes, sodium, and potassium. The most important of these hormones is aldosterone, which acts on the kidney to regulate blood levels of sodium and potassium ions

. Gonadocorticoids

sex hormones released from the adrenal cortex instead of the gonads (testes and ovaries), but the small amounts secreted by the adrenal cortex contribute to the secondary sex characteristics, such as breast and beard development, and are necessary for reproduction

adrenal medulla

the inner portion of the adrenal gland, secretes two nonsteroidal hormones called catecholamines. The two hormones, adrenaline (epinephrine) and noradrenaline (norepinephrine), are the stress hormones that exert physiologic changes during times of stress (the fight-or-flight response)

ovaries

female gonads; two small glands located in the upper pelvic cavity, on either side of the uterine wall, near the fallopian tubes; each is almond shaped and held in place by ligaments. Ovaries produce mature ova as well as two hormones (estrogen and progesterone) responsible for female sex characteristics and regulation of the menstrual cycle. Estrogen promotes maturation of the ova in the ovary and prepares the uterine lining for implantation of a fertilized egg. It is also responsible for the development and maintenance of secondary female characteristics that occur in puberty, such as breast development, growth of pubic and axillary hair, widened pelvis, general growth spurt, and onset of menstruation. Progesterone is responsible for preparation and maintenance of the uterus in pregnancy, and for the development of the placenta after implantation of a fertilized ovum

pancreas

an elongated structure located behind the stomach in the left upper quadrant. The specialized cells that produce hormones are called the islets of Langerhans; these cells produce two hormones, insulin and glucagon, and both play a role in maintaining normal glucose levels. The islets of Langerhans carry on the endocrine functions of the pancreas; other cells within the organ carry on its exocrine functions, e.g., the secretion of digestive enzymes.

Insulin

produced in the beta cells of the pancreas, is necessary for glucose to pass from the blood into the cells and be used for energy. Insulin also promotes the conversion of glucose into glycogen for storage (glycogenesis) in the liver. When blood sugar is high (hyperglycemia), the pancreas is stimulated to release insulin and convert the excess glucose into glycogen.

Glucagon

produced in the alpha cells, increases blood levels of glucose by stimulating the breakdown of glycogen stored in the liver cells; glycogen is the storage form of carbohydrate in the body. This process, called glycogenolysis, helps maintain blood glucose levels between meals; glucagon also helps synthesize glucose from amino acids and glycerol derived from protein and triglycerides, respectively (gluconeogenesis), to elevate blood glucose levels

parathyroid

consists of four small nodules of tissue embedded in the back side of the thyroid glands. When blood calcium levels are low, the parathyroid glands secrete parathyroid hormone or parathormone (PTH), which increases blood calcium levels in three ways: (1) calcium is released from the bones; (2) less calcium is excreted by the kidneys; and (3) the kidney activates Vitamin D which increases calcium absorption in the gastrointestinal tract

pineal gland

the pineal gland is a cone-shaped structure attached by a stalk to the posterior wall of the cerebrum. This gland secretes melatonin, the hormone that responds to darkness in the external environment. Darkness stimulates nerve impulses in the eyes to decrease and the secretion of melatonin to increase. The pineal gland functions as a "biological clock" to regulate patterns of sleeping, eating, and reproduction

pituatary gland (hypophysis)

also known as the hypophysis, the pituitary gland is about the size of a pea and is located on the underside of the brain in a depression at the base of the skull, protected by the brain above it and the nasal cavities below it. The pituitary gland is connected by a thin stalk-like projection to the hypothalamus and contains two major parts: the anterior pituitary and the posterior pituitary lobes. The pituitary is a very complex gland that is often referred to as the "master gland," because it produces many hormones that affect body functions and because it travels throughout the body to stimulate other endocrine glands to secrete hormones. The pituitary gland secretes growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), adenocorticotropin (ACTH), gonadotropins (FSH, LH), antidiuretic hormone (ADH), and oxytocin

testes

male gonads, also known as testicles, are two small egg shaped glands suspended from the inguinal region of the male by the spermatic cord and surrounded by the scrotal sac. After descending from high in the abdominal cavity during fetal growth, testes descend shortly before birth into the scrotum. Testes are the primary organs of the male reproductive system. The testes produce male sperm cells and secrete testosterone, the male hormone necessary for secondary sex characteristics that appear in the male during puberty, such as growth of the beard and pubic hair, growth of skeletal muscles, deepening of the voice, and enlargement of the testicles, penis, and scrotum

thymus

a single gland located behind the sternum in the mediastinum; it resembles a lymph gland in structure because it not only is a part of the lymphatic system, but it also is a hormone-secreting endocrine gland. The thymus is large in children, but shrinks with age until there is only a trace of active tissue in older adults. The gland secretes thymosin and thymopoietin which stimulates the production of T cells, the specialized lymphocytes involved in the immune response

thyroid

consisting of a right and left lobe, the thyroid gland is a U- or H-shaped gland located in front of the neck just below the larynx; the lobes are connected by a narrow piece of thyroid cartilage that produces the prominence on the neck known as Adam's apple. Thyroid hormones affect metabolism, brain development, breathing, heart and nervous system functions, body temperature, muscle strength, skin dryness, menstrual cycles, weight, and cholesterol levels. The thyroid gland produces three hormones

Thyroxine (T4)

helps maintain normal body metabolism

Triiodythyronine (T3)

a chemically similar compound, helps regulate growth and development and control metabolism and body temperature

Calcitonin (thyrocalcitonin)

regulates the level of calcium in the blood. It lowers the blood calcium by inhibiting the release of calcium from the bones by a negative feedback loop when blood calcium levels are high

bursitis

inflammation of a bursa

collagen disease

a group of diseases with widespread pathologic changes in connective tissue, e.g., systemic lupus erythematosus

gout

a hereditary form of arthritis caused by accumulation of uric acid crystals in the great toe and fingers

kyphosis

humpback or hunchback; a spinal deformity

lordosis

exaggerated forward curvature of the lumbar spine

muscular dystrophy

genetic disease with progressive atrophy of skeletal muscles

Osteoarthritis (OA)

degeneration of joint cartilage and underlying bone causing pain and stiffness, especially in the hip, knee, and thumb joints; also degenerative joint disease (DJD)

Osteoporosis

porous condition of bones; occurs primarily in postmenopausal women

rheumatoid arthritis (RA)

disorders marked by inflammation, degeneration, or metabolic derangement of the connective tissue structures, especially the joints; accompanied by pain, stiffness, or limitation of motion

sarcoma (osteogenic)

a malignant tumor of bone

scoliosis

lateral curvature of the spine

systemic lupus erythematosus (SLE)/lupus

a chronic inflammatory disease affecting many systems of the body, most often the joints and muscles, causing pain and fatigue

Tendinitis

inflammation of a tendon

acromegaly

hypersecretion of the pituitary growth hormone (GH) after maturity; causes abnormal enlargement of the extremities of the skeleton, nose, jaws, fingers, and toes. Most common cause is a noncancerous tumor of the pituitary gland

Congenital growth hormone deficiency

abnormalities in the development of the pituitary gland and surrounding structures, resulting in short stature in children unless treated with growth hormone (GH); puberty may be delayed or may not occur

Cushing's Disease

excessive growth of the pituitary gland caused by a tumor of the pituitary gland; results in the release of too much ACTH, which then leads to overproduction of cortisol. Symptoms of excess cortisol are obesity, weakness, moon face, edema, and high blood pressure

diabetes insipidus

insufficient excretion of antidiuretic hormone (ADH; vasopressin) by the posterior pituitary gland; most common cause is damage to the pituitary gland (or hypothalamus) from head injury, surgery, or tumors. Lack of ADH causes the kidney tubules to fail to reabsorb needed water and salts. Clinical symptoms include polyuria (increased urination) and polydipsia (increased thirst); excessive thirst results in drinking large volumes of water and a very dilute urine

Hypopituitarism

pituitary insufficiency may be caused by a tumor or injury to the pituitary gland. Usually affects the anterior pituitary and releasing hormones necessary for normal functioning of other endocrine glands (thyroid, adrenal cortex, ovaries and testes)

Hyperprolactinemia

higher than normal amounts of prolactin in the blood and production of breast milk in women when not pregnant or nursing; caused by tumor of the pituitary gland, certain medications, and chronic liver or kidney disease

Simmonds' disease (panhypopituitarism)

generalized hypopituitarism owing to absence of or damage to the pituitary gland; results in loss of function of thyroid and adrenal glands as well as gonads, testes, and ovaries; symptoms are exhaustion, emaciation, cachexia, and lack of secondary sex characteristics

congenita hypothyroidism (cretinism)

lack of thyroid secretion that affects infants from birth (congenital). The thyroid gland may be absent or severely reduced in size (hypoplastic) or abnormally located. If untreated, congenital hypothyroidism can lead to intellectual disability and slow physical growth. In the United States, infants are tested at birth and treated to allow for normal growth and development

Grave's disease

toxic diffuse goiter; autoimmune disease and most common cause of hyperthyroidism in the United States. Symptoms are nervousness, difficulty sleeping, fatigue, weight loss, goiter, and a protrusion of the eyeballs

Hashimoto's Disease

chronic lymphocytic thyroiditis; most common cause of hypothyroidism in the United States. An autoimmune disease of the thyroid gland, with replacement of normal tissue with lymphoid tissue. The end result is a lack of production and secretion of thyroid hormone

thyroid nodule

solid or fluid-filled lumps within the thyroid gland; most are benign (noncancerous), although in some cases, the nodules produce excessive amounts of thyroxine

myxedema

advanced form of hypothyroidism in adults; a dry, waxy type of swelling with deposits of mucin in the skin, swollen lips, and thickened nose

Primary hyperparathyroidism (PHPT)

overactive parathyroid gland with excessive secretion of parathyroid hormone (PTH); most common cause is a benign tumor of the parathyroid gland. PTH increases serum calcium by releasing calcium from bone, reabsorption of calcium by the kidney, and increasing phosphorous excretion by the kidney

Secondary hyperparathyroidism

overactive parathyroid gland secondary to chronic kidney failure, the most common disease causing secondary hyperparathyroidism

Addison's disease (adrenal insufficiency)

hypofunction of the adrenal gland; autoimmune disorder with inadequate amounts of hormones secreted by the adrenal gland (cortisol, aldosterone, and androgens); secondary cause is damage to the pituitary gland. Symptoms include a bronze-like pigmentation of the skin, dizziness, low blood pressure, low blood sugar, vomiting, and diarrhea

congenital adrenal hyperplasia (CAH)

lack of enzymes involved in the biosynthesis of cortisol and aldosterone. In many cases, CAH results in lack of cortisol and overproduction of androgen. causing development of male characteristics in girls and early sexual development in boys

Cushing's syndrome

adrenal glands produce too much cortisol; often caused by high doses of corticosteroid medication treatment for autoimmune diseases, e.g., rheumatoid arthritis or asthma. Untreated Cushing syndrome can lead to diabetes, high blood pressure, and osteoporosis

pheochromocytoma (hyperaldosteronism)

"pheochromo" means dusky color; tumor of the adrenal medulla and excessive production of aldosterone. excessive aldosterone acts on the kidneys to retain sodium and water and to excrete too much potassium resulting in hypertension; symptoms include headache, rapid heart rate, and tremors

plycystic ovary syndrome (PCOS)

hyperandrogenism (abnormally elevated androgen levels); condition in women characterized by the absence of ovulation and menstrual periods, infertility, acne, excess body hair, and metabolic syndrome (obesity, prediabetes, hyperlipidemia)

Primary hypogonadism

abnormality in the testicles resulting in lack of testosterone production; can begin during fetal development, before puberty, or during adulthood. Lack of testosterone during fetal development may cause impaired growth of the external sex organs. During puberty, hypogonadism may delay puberty or cause incomplete development

secondary hypogonadism

failure of pituitary gland to send chemical messages to the testicles to produce testosterone. Certain diseases and aging can also lower production of testosterone

diabetes mellitus (Type 1)

autoimmune disease with destruction of insulin-producing cells in the pancreas. Most commonly diagnosed in children and young adults. Symptoms are high blood sugar, excessive urination (polyuria), thirst (polydipsia), hunger (polyphagia), emaciation, and weakness. Treatment requires daily insulin injections

Diabetes mellitus (type 2)

insulin resistance--insulin is produced, but the insulin doesn't function properly--or lack of insulin secretion. Most common form of diabetes; usually diagnosed in those over 40 years of age and in those who are obese

gestational diabetes

develops during pregnancy, most often in women with a family history of diabetes. Typically, it disappears after delivery, although the condition is associated with an increased risk of developing type 2 diabetes later in life

humoral stimuli

An example is regulation of blood glucose by the pancreas. High blood glucose levels stimulate the pancreas to secrete insulin while low blood glucose levels stimulate the pancreas to secrete glucagon. Insulin lowers blood glucose while glucagon raises blood glucose.

neural stimuli

An example is the response of the sympathetic nervous system to stress. In response to stress, the adrenal gland secretes epinephrine and norepinephrine; other names for these hormones are adrenaline and noradrenaline. In times of short-term stress, for example, narrowly escaping a bicycle accident, these hormones increase heart rate and blood glucose to prepare the body for a quick response.

antistreptolysin O (ASO)

serum test for antibodies against streptolysin O, produced by group A streptococcus bacteria. Causes strep throat; complication of infection is rheumatic fever with symptoms of swelling and pain in the joints

Antinuclear antibodies (AN)

serum test used as screening for autoimmune diseases

C-reactive protein (CRP)

protein present in blood serum in inflammatory conditions, including autoimmune disorders

Rheumatoid Factor (RF)

autoantibody (antibody directed against an organism's own tissues) found in rheumatoid arthritis

sed rate (erythrocyte sedimentation rate [ESR])

blood test for inflammatory activity; screening test for autoimmune diseases

electromyogram (electromyography)

the film record made and the study of muscular contraction

magnetic resonance imaging (MRI)

noninvasive diagnostic tool that uses a magnetic field and radio waves to create 3-D images of the skeletal system, especially bones and joints

myelogram

the film produced by radiography of the spinal cord after injection of a dye into the spinal cavity

myogram

a record produced by myography; same as electromyogram

amputation

Removal of a limb or other appendage of the body because of trauma or disease

arthrocentesis

puncture of a joint cavity to remove fluid

arthroplasty

surgery to relieve pain and restore range of motion by realigning or reconstructing a joint; e.g., of the wrist, knee, or hip

arthroscopy

examination of the interior of a joint with an endoscope

arthrotomy

surgical creation of an opening into a joint such as for drainage

external fixation

the process of making a bone immovable; a rod and screws are placed on the outside of the bone

fracture reduction

the correction of a fracture, luxation

Joint Replacement (Arthroplasty)

replacement of a damaged joint with an artificial joint to relieve chronic pain caused by osteoporosis or rheumatoid arthritis; most commonly for the knee or hip

Kyphoplasty

treatment of a compression fracture of the vertebrae by inserting a balloon into the spine to create a space for injecting a bone cement mixture; done to stabilize the vertebrae to prevent pinching of the spinal cord and pain

laminectomy with discectomy

laminectomy is the excision of the lamina or spongy tissue between the discs in the spine; discectomy is the excision of an injured disc; procedures used to relieve the symptoms of a herniated disc

meniscectomy

excision of a meniscus, e.g., the fibrocartilage of the knee joint

transplantation

insertion of donor organ or tissue, e.g., meniscus transplant in someone with a torn meniscus

spondylosyndesis

surgical procedure in which vertebrae are joined; spinal fusion

electrical stimulation

a process used to heal fractures more quickly

traction

the act of drawing or pulling to align a bone or bones after a fracture

ORIF

open reduction internal fixation

CRP

C-reactive protein

DJD

degenerative joint disease

MRI

magnetic resonance imaging

negative feedback

the mechanism that controls hormone secretion and maintains stable blood levels of hormones. The feedback loop is the response to changing blood levels of a hormone. As hormone levels rise, negative feedback inhibits the system and hormone secretion decreases

A1c/HbA1c (glycated hemoglobin)

measurement of the level of hemoglobin A1c determines average blood sugar concentrations for the preceding 2-3 months; normal levels below 5.7 percent indicate diabetes mellitus is well controlled

ACTH (adrenocorticotropic hormone)

measured in the blood to evaluate for disorders of the pituitary and adrenal glands

cortisol

measured in the blood or saliva to evaluate for diseases of the adrenal gland

estradiol

measured in the blood to evaluate for normal functioning of the ovaries (in females)

prolactin

measured in the blood when women (who are not pregnant or breastfeeding) secrete breast milk

serum calcium

measured to evaluate for diseases of the parathyroid glands

serum potassium

measured to evaluate for tumors of the adrenal gland that cause excessive urinary excretion of potassium

testosterone

measured in the blood to evaluate for diseases of the adrenal gland or testes (in males)

Thyroxine (T4)

measured in the blood to evaluate for diseases of the thyroid

triiodothyronine (T3)

measured in the blood to evaluate for diseases of the thyroid

urine calcium

measured to evaluate for diseases of the parathyroid glands

thryoid scan

use of radioactive iodine tracer to examine the structure and function of the thyroid gland; used to evaluate for thyroid nodules or goiter or an overactive thyroid gland

radioactive iodine uptake (RAIU)

test that measures the amount of radioactive iodine taken up by the thyroid gland; used to evaluate functioning of the thyroid gland

hypoglycemic agent

drug for treating diabetes mellitus to normalize blood glucose