Chapter 14 Endocrine System

parathyroid/o

parathyroid glands

-toxic

pertaining to poison

thyr/o/toxic

pertaining to poison of thyroid gland

pituitar

pituitary gland

toxic/o

poison

kal

potassium (an electrolyte)

kal/i

potassium (an electrolyte)

kal/emia

potassium (an electrolyte) blood condition

Posterior Pituitary Hormones

(Neurohypophysis) - Antidiuretic hormone (ADH) o disorders- Hyposecretion causes diabetes insipidus (DI).

Anterior Pituitary Hormones

(adenoypophysis) - Adrenocorticotropic hormone (ACTH)- o target organ and functions- Adrenal cortex—promotes secretion of corticosteroids, especially cortisol o Disorders- Hypersecretion causes Cushing disease. - Growth hormone (GH) or somatotropin o Target Organ and functions: Regulates growth of bone, muscle, and other body tissues. Increases use of fats for energy o Disorders: Hyposecretion during childhood and puberty causes pituitary dwarfism.. Hypersecretion during childhood and puberty causes gigantism; hypersecretion during adulthood causes acromegaly. - Thyroid-stimulating hormone (TSH) or thyrotropin o Target organ and functions- Thyroid gland—stimulates secretion of thyroid hormones o Disorders- Hyposecretion in infants causes cretinism; hyposecretion in adults causes myxedema. Hypersecretion causes Graves disease, which results in exophthalmos.

Cushing Syndrome

- Cushing syndrome is a cluster of symptoms produced by excessive amounts of cortisol, adrenocorticotropic hormone (ACTH), or both circulating in the blood.

Adrenal Medullary Hormones

- Epinephrine and norepinephrine o target organs and functions- and Sympathetic nervous system target organs—hormone effects mimic sympathetic nervous system activation (sympathomimetic), increase metabolic rate and heart rate, and raise blood pressure by promoting vasoconstriction o disorders- Hyposecretion has no known significant effect. Hypersecretion causes prolonged "fight-or-flight" reaction and hypertension.

Pancreatic Hormones

- Glucagon o target organs and functions- Liver and blood—raises the blood glucose level by accelerating conversion of glycogen into glucose in the liver (glycogenolysis) and other nutrients into glucose in the liver (gluconeogenesis) and releasing glucose into blood (glycogen to glucose) o disorders- A deficiency in glucagon may cause persistently low blood glucose levels (hypoglycemia). - Insulin o target organs and function- Tissue cells—lowers blood glucose level by accelerating glucose transport into cells and the use of that glucose for energy production (glucose to glycogen) o disorders- Hyposecretion of insulin causes diabetes mellitus. Hypersecretion of insulin causes hyperinsulinism.

Adrenal Hormones Adrenal Cortex Hormones

- Glucocorticoids (mainly cortisol) o target organs and functions- Body cells—promote gluconeogenesis; regulate metabolism of carbohydrates, proteins, and fats; and help depress inflammatory and immune responses o disorders- Hyposecretion causes Addison disease. Hypersecretion causes Cushing syndrome. - Mineralocorticoids (mainly aldosterone) o target organs and functions- Kidneys—increase blood levels of sodium and decrease blood levels of potassium in the kidneys o disorders- Hyposecretion causes Addison disease. Hypersecretion causes aldosteronism. - Sex hormones (any of the androgens, estrogens, or related steroid hormones produced by the ovaries, testes, and adrenal cortices) o target organs and functions- In females, possibly responsible for female libido and source of estrogen after menopause (otherwise, insignificant effects in adults) o disorders- Hypersecretion of adrenal androgen in females leads to virilism (development of male secondary sex characteristics). Hypersecretion of adrenal estrogen and progestin secretion in males leads to feminization (development of female secondary sex characteristics). Hyposecretion has no known significant effect.

Pancreas

- It functions as an exocrine and endocrine gland. In its exocrine role, it carries digestive secretions from the pancreas to the small intestine through a large pancreatic duct. The digestive secretions assist in the breakdown of proteins, starches, and fats in the small intestine. In its endocrine role, the pancreas secretes two other hormones: glucagon, and insulin.

CONNECTING BODY SYSTEMS—ENDOCRINE SYSTEM

- The main function of the endocrine system is to secrete hormones that have a diverse effect on cells, tissues, organs, and organ systems. Specific functional relationships between the endocrine system and other body systems are summarized here. - Blood, Lymphatic, and Immune o Hormones from the thymus stimulate lymphocyte production. o Glucocorticoids depress the immune response and inflammation. - Cardiovascular o Hormones influence heart rate, contraction strength, blood volume, and blood pressure. o Estrogen helps maintain vascular health in women. - Digestive o Hormones help control digestive system activity. o Hormones influence the motility and glandular activity of the digestive tract, gallbladder secretion, and secretion of enzymes from the pancreas. o Insulin and glucagon adjust glucose metabolism in the liver. - Female Reproductive o Hormones play a major role in the development and function of the reproductive organs. o Hormones influence the menstrual cycle, pregnancy, parturition, and lactation. o Sex hormones play a major role in the development of secondary sex characteristics. o The hormone oxytocin triggers contraction of the pregnant uterus and later stimulates the release of breast milk. - Integumentary o Hormones regulate the activity of the sebaceous glands, the distribution of subcutaneous tissue, and hair growth. o Hormones stimulate melanocytes to produce skin pigment. o The hormone estrogen increases skin hydration. - Male Reproductive o Hormones play a major role in the development and function of the reproductive organs. o Sex hormones play a major role in the development of secondary sex characteristics. o Hormones play a role in sexual development, sex drive, and sperm production. - Musculoskeletal o Hormone secretions influence blood flow to muscles during exercise. o Hormones influence muscle metabolism, mass, and strength. o Hormones from the pituitary and thyroid glands and the gonads stimulate bone growth. o Hormones govern blood calcium balance. - Nervous o Several hormones play an important role in the normal maturation and function of the nervous system. - Respiratory o Hormones stimulate red blood cell production when the body experiences a decrease in oxygen. o Epinephrine influences ventilation by dilating the bronchioles; epinephrine and thyroxine stimulate cell respiration. - Urinary o Hormones regulate water and electrolyte balance in the kidneys.

Thyroid Hormones

- Thyroxine (T4) and triiodothyronine (T3) o target organs and functions: Increases energy production from all food types. Increases rate of protein synthesis o Disorders: Hyposecretion in infants causes cretinism; hyposecretion in adults causes myxedema. Hypersecretion causes Graves disease, which results in exophthalmos.

Drugs Used to Treat Endocrine Disorders- corticosteroids

- corticosteroids o Therapeutic action- Replace hormones lost in adrenal insufficiency (Addison disease). Corticosteroids are also widely used to suppress inflammation, control allergic reactions, reduce rejection in transplantation, and treat some cancers. o Generic and Trade Names- cortisone, hydrocortisone

Drugs Used to Treat Endocrine Disorders- growth hormone replacements

- growth hormone replacements o Therapeutic action- Increase skeletal growth in children and growth hormone deficiencies in adults. Growth hormones increase spinal bone density and help manage growth failure in children. o Generic and trade names- somatropin (recombinant)

Differences Between Type 1 and Type 2 Diabetes

- type 1 diabetes o onset: Symptoms usually start in childhood or young adulthood. Patients commonly seek medical attention because they experience serious symptoms associated with a high blood glucose level. o low blood glucose: Episodes of low blood glucose level (hypoglycemia) are common. o prevention: Prevention is not possible. - type 2 diabetes o onset: The disease is usually discovered during a routine checkup, commonly before symptoms occur. It is commonly diagnosed in adulthood, but an increasing number of children are being diagnosed with the disease. o low blood glucose: There are no episodes of low blood glucose level, unless the person is taking excessive insulin or certain diabetes medicines. o prevention: Healthy lifestyle measures to prevent or delay onset include maintaining a healthy weight, eating sensibly, and exercising regularly.

Adrenal Cortex The adrenal cortex secretes three types of steroid hormones:

1. Mineralocorticoids, mainly aldosterone, are essential to life. These hormones act mainly through the kidneys to maintain the balance of electrolytes (sodium and potassium) in the body. More specifically, aldosterone causes the kidneys to conserve sodium and excrete potassium (K). At the same time, it promotes water conservation by reducing urine output. 2. Glucocorticoids, mainly cortisol, influence the metabolism of carbohydrates, fats, and proteins. The glucocorticoid with the greatest activity is cortisol. It helps regulate the concentration of glucose in the blood, protecting against low blood glucose levels between meals. Cortisol also stimulates the breakdown of fats in adipose tissue and releases fatty acids into the blood. The increase in fatty acids causes many cells to use relatively less glucose. 3. Sex hormones, including androgens, estrogens, and progestins, help maintain secondary sex characteristics, such as development of the breasts in females and distribution of body hair in adults.

hypervolemia

Abnormal increase in the volume of blood plasma (liquid part of the blood and lymphatic fluid) in the body. Hypervolemia commonly results from retention of large amounts of sodium and water by the kidneys.

antagonistic

Acting in opposition; mutually opposing

Adrenal Cortex - The adrenal cortex is mainly associated with

Addison disease and Cushing syndrome.

sympathomimetic

Agent that mimics the effects of the sympathetic nervous system, the division of the nervous system that increases the "fight or flight" response. Epinephrine and norepinephrine are sympathomimetic hormones because they produce effects that mimic those brought about by the sympathetic nervous system.

giantism

Hypersecretion of GH during childhood, resulting in abnormal increase in the length of long bones and extreme height (up to 8′ tall) but with body proportions remaining about normal (See Fig. 14-8.)

A1c test

Blood test used to diagnose and manage type 1 and type 2 diabetes; also called glycated hemoglobin, hemoglobin A1c, and HbA1c.The A1c test result reflects the average blood sugar level for the past two to three months by measuring the percentage of hemoglobin (a protein in red blood cells that carries oxygen) coated with sugar (glycated).

hypercalcemia

Condition in which the calcium level in the blood is higher than normal

hyperkalemia

Condition in which the potassium level in the blood is higher than normal. Potassium is a critical electrolyte in the proper functioning of nerve and muscle cells, including the heart. Severe hyperkalemia requires immediate treatment because it can lead to cardiac arrest and death.

Diabetes

Diabetes is a general term that, when used alone, refers to diabetes mellitus (DM). DM is a chronic metabolic disorder of impaired carbohydrate, protein, and fat metabolism resulting from insufficient production of insulin or the body's inability to use insulin properly.

acromegaly

Hypersecretion of GH in adults, resulting in enlargement of bones in the extremities and head (See Fig. 14-7.)

diabetes insipidus (DI)

Disorder characterized by excessive thirst (polydipsia) and excessive urination (polyuria) due to inadequate production of antidiuretic hormone (ADH)

hirsutism

Excessive distribution of body hair, especially in women

glucagon

Hormone produced by pancreatic alpha cells that stimulates the liver to change stored glycogen (a starch form of sugar) to glucose. Glucagon opposes the action of insulin. It is used to reverse hypoglycemic reactions in insulin shock.

dwarfism

Hyposecretion of GH during childhood, resulting in extreme shortness in stature (final height of only 3' to 4') but normal body proportions

Addison Disease Treatment

If treatment for this condition begins early (usually with adrenocortical hormone therapy), the prognosis is excellent. If untreated, the disease will continue a chronic course with progressive but relatively slow deterioration. In some patients, the deterioration may be rapid.

diuresis

Increased formation and secretion of urine. Diuresis commonly occurs in diabetes mellitus. Alcohol and coffee are common diuretics that increase formation and secretion of urine.

hyponatremia

Lower-than-normal level of sodium in the blood. Hyponatremia is commonly caused by drinking too much water when exercising (especially in the heat), thereby diluting the amount of sodium in the blood.

exophthalmometry

Measures the degree of forward displacement of the eyeball (exophthalmos) as seen in Graves disease

Adrenal Medulla compare and contrast epinephrine and Norepinephrine

Of the two hormones, epinephrine is secreted in larger amounts. In the physiological response to stress, epinephrine is responsible for maintaining blood pressure and cardiac output, dilating airways, and raising blood glucose levels. All of these functions are useful for frightened, traumatized, injured, or sick persons. Norepinephrine reduces the diameter of blood vessels in the periphery (vasoconstriction), thereby raising blood pressure.

adrenal/ectomy

excision of the adrenal glands

growth hormone (GH) disorders

Pituitary gland disorder that generally involves a hypersecretion or hyposecretion of GH and commonly results from a pituitary tumor

-ectomy

excision, removal

parathyroid/ectomy

excision, removal of parathyroid glands

acr/o

extremity

ophthalm/o

eye

electrolytes

Salts and minerals that conduct electrical impulses in the body. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost every major biochemical reaction in the body. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate.

glucose tolerance test (GTT)

Screening test in which a dose of glucose is administered and blood samples are taken at regular intervals following the dose to determine how quickly glucose is cleared from the blood. GTT is performed to diagnose prediabetes and gestational diabetes.

glucose

Simple sugar that is the end product of carbohydrate digestion. Glucose is found in many foods, especially fruits, and is a major source of energy for living organisms. Analysis of blood glucose levels is an important diagnostic test in diabetes and other disorders.

short-term versus long-term hormonal action causes

Some hormonal actions cause short-term changes, such as a faster heartbeat or sweaty palms during a panic situation. Others control long-term changes, such as bone and muscle development.

How does some hormones help maintain continuous body functions?

Still other hormones help maintain continuous body functions, such as a balance of body fluids and a normal metabolism.

fasting blood sugar (FBS)

Test that measures glucose levels in a blood sample following a fast of at least 8 hours. This test helps diagnose diabetes and monitor glucose levels in diabetic patients.

-gen

forming, producing, origin

endocrinologist

The physician who specializes in the diagnosis and treatment of endocrine disorders is known as an endocrinologist.

-genesis

forming, producing, origin

andr/o/gen

forming, producing, origin male

gluc/o/genesis

forming, producing, origin of sugar, sweetness

Thyroid Disorders

Thyroid gland disorders are common and may occur at any time during life. They may be the result of a developmental problem, injury, disease, or dietary deficiency.

Most hormone deficiencies result from

genetic defects in the glands, surgical removal of the glands, or production of poor-quality hormones.

eu

good

In general, hormones regulate

growth, metabolism, reproduction, energy level, and sexual characteristics.

panhypopituitarism

Total pituitary impairment that brings about a progressive and general loss of hormone activity. Panhypopituitarism can lead to symptoms associated primarily with insufficiency of gonadotropins, growth hormones, and thyroid hormones

ketosis

When body cells are deprived of glucose, their principal energy fuel, they begin to metabolize proteins and fats. Fat metabolism produces ketones, which enter the blood, causing a condition called ketosis.

The thymus gland is

a butterfly-shaped gland that lies at the base of the neck and is formed mostly of lymphatic tissue. The thymus functions as part of the body's immune system and part of the endocrine system.

-metry

act of measuring

pancreat/o

pancreas

Adrenal Gland Disorders - The _________________________ and ____________________ have their own structures and functions and their own sets of associated disorders.

adrenal cortex adrenal medulla

adren/o

adrenal glands

adrenal/o

adrenal glands

pan-

all

Signs and symptoms of hyperthyroidism include

an elevated metabolic rate, abnormal weight loss, excessive perspiration, muscle weakness, and emotional instability. Also, the eyes are likely to protrude (exophthalmos) because of edematous swelling in the tissues behind them. At the same time, the thyroid gland is likely to enlarge, producing goiter.

Insulin and glucagon function

antagonistically, so that normal secretion of both hormones ensures a blood glucose level that fluctuates within normal limits.

-emia

blood condition

hyper/calc/emia

blood condition of excessive, above normal calcium

hypo/glyc/emia

blood condition of under, below sugar, sweetness. Common causes of hypoglycemia include too much insulin, excessive secretion of insulin by the islet cells of the pancreas, and dietary deficiency.

calc

calcium

calc/o

calcium

Deficiency of thyroid hormone (hypothyroidism) that develops in infants is called

called cretinism. If not treated, this disorder leads to mental retardation, impaired growth, low body temperatures, and abnormal bone formation. Usually these symptoms do not appear at birth because the infant has received thyroid hormones from the mother's blood during fetal development.

Regardless of the cause, Cushing syndrome alters

carbohydrate and protein metabolism and electrolyte balance. Overproduction of mineralocorticoids and glucocorticoids causes blood glucose concentration to remain high, depleting tissue protein. In addition, sodium retention causes increased fluid in tissues, leading to edema. These metabolic changes produce weight gain and may cause structural changes, such as a moon-shaped face, grossly exaggerated head and trunk, and pencil-thin arms and legs. Other symptoms include fatigue, high blood pressure, and excessive hair growth in unusual places (hirsutism), especially in women.

-esis

condition

-ism

condition

hyper/thyroid/ism

condition of excessive, above normal thyroid gland

Addison Disease - Addison disease, also called

corticoadrenal insufficiency, is a relatively uncommon chronic disorder caused by a deficiency of cortical hormones. It commonly results from damage to or atrophy of the adrenal cortex.

Pancreatic Disorders - By far, the most common pancreatic disorder is

diabetes.

di-

double

-megaly

enlargement

adren/o/megaly

enlargement of adrenal glands

thyr/o/megaly

enlargement of thyroid gland

The cells of the adrenal medulla secrete two closely related hormones:

epinephrine (adrenaline) and norepinephrine (noradrenaline). Both hormones are activated when the body responds to crisis situations, and they are considered sympathomimetic agents because they produce effects that mimic those brought about by the sympathetic nervous system. Because hormones of the adrenal medulla merely intensify activities set into motion by the sympathetic nervous system, their deficiency does not cause dysfunction.

hyper-

excessive, above normal

Each adrenal gland is divided into two sections, each

having its own structure and function. The outer adrenal cortex makes up the bulk of the gland, and the adrenal medulla makes up the inner portion. Although these regions are not sharply divided, they represent distinct glands that secrete different hormones.

The pituitary gland, or _____________ , is a

hypophysis pea-sized organ located at the base of the brain. It is known as the master gland because it regulates many body activities and stimulates other glands to secrete their own specific hormones.

endo-

in, within

-tomy

incision

pancreat/o/tomy

incision of pancreas

The endocrine system also maintains an

internal state of equilibrium in the body (homeostasis) so that all body systems function effectively.

Endocrinology

is the branch of medicine concerned with endocrine glands and hormones.

andr/o

male

poly

many

poly/uria

many urine. Some causes of polyuria are diabetes, use of diuretics, excessive fluid intake, and hypercalcemia.

poly

many, much

poly/dipsia

many, much thirst. Polydipsia is one of the three "polys" (along with polyphagia and polyuria) associated with diabetes.

Thyroid hormone (TH) is the body's major ____________________ . _________________.

metabolic hormone.

Parathyroid Disorders - Decreased calcium causes

muscle twitches and spasms (tetany).

When hypothyroidism develops during adulthood, it is known as

myxedema. The signs and symptoms of this disease include edema, low blood levels of T3 and T4, weight gain, cold intolerance, fatigue, depression, muscle or joint pain, and sluggishness.

- Both hormones glucose and insulin play important roles in regulating blood glucose (sugar) levels:

o Glucagon stimulates the release of glucose from storage sites in the liver when blood glucose levels are low (hypoglycemia), thereby raising the blood glucose level. o Insulin clears glucose molecules from the blood by promoting their storage in tissues as carbohydrates when blood glucose levels are high (hyperglycemia), thereby lowering the blood glucose level and enabling the cells to use glucose for energy.

Causes of this excess secretion in Cushing Syndrome include the following:

o Long-term administration of steroid drugs (glucocorticoids) in treating such diseases as rheumatoid arthritis, lupus erythematosus, and asthma o Adrenal tumor, resulting in excessive production of cortisol o Cushing disease, a pituitary disorder caused by hypersecretion of ACTH from an adenoma in the anterior pituitary gland.

Other hormones, such as calcitonin and some pituitary gland hormones, have only

one or a few target organs.

ex-

out, out from

exo

outside

The (4) adrenal glands are

paired organs covering the superior surface of the kidneys. Because of their location, the adrenal glands are also known as suprarenal glands.

The primary function of the endocrine system is to

produce specialized chemicals called hormones that directly enter the bloodstream and travel to specific tissues or organs of the body called targets.

For example, thyroid-stimulating hormone (TSH) binds to

receptors on cells of the thyroid gland, causing it to secrete thyroxine. However, it does not bind to cells of the ovaries because ovarian cells do not have TSH receptors. Some hormones, such as insulin and thyroxine, have many target organs.

-oid

resembling

eu/thyr/oid

resembling good thyroid gland

The treatment goal for this disease, Cushing syndrome, is to

restore serum cortisol to normal levels. Nevertheless, treatment varies with the cause and may necessitate radiation, drug therapy, surgery, or a combination of these methods.

home/o

same, alike

-crine

secrete

crin/o

secrete

endo/crine

secrete in, within

exo/crine

secrete outside. Exocrine glands (sweat and oil glands) secrete their products outwardly through excretory ducts.

natr

sodium (an electrolyte)

-logist

specialist in the study of

toxic/o/logist

specialist in the study of poison. Toxicologists study the effects of toxins and antidotes used for treatment of toxic disorders.

-stasis

standing still

home/o/stasis

standing still same, alike

-logy

study of

gluc/o

sugar, sweetness

glyc/o

sugar, sweetness

glycos

sugar, sweetness

glycos/o

sugar, sweetness

glycos/uria

sugar, sweetness in urine

glycos/uria

sugar, sweetness urine

Addison Disease - Hypofunction of the adrenal cortex interferes with

the body's ability to handle internal and external stress. Other clinical manifestations include muscle weakness, anorexia, gastrointestinal symptoms, fatigue, hypoglycemia, hypotension, low blood sodium (hyponatremia), and high serum potassium (hyperkalemia).

Hyperglycemia and ketosis are responsible for

the host of troubling and, commonly, life-threatening symptoms of diabetes mellitus.

The ductless glands of the endocrine system include

the pituitary, thyroid, parathyroid, adrenal, pancreatic, pineal, and thymus glands and the ovaries and testes.

endo/crin/o/logy

the study of secretion in, within. Endocrinology is the branch of medicine concerned with endocrine glands and hormones.

Although hormones travel throughout the body in blood and lymph, they affect only

the target tissues or organs that have specific receptors for the hormone. Once bound to the receptor, the hormone initiates a specific biological effect.

Hyperthyroidism is a condition in which

the thyroid gland produces excessive amounts of thyroid hormone. The most common form is Graves disease, also known as thyrotoxicosis/autoimmune hyperthyroidism, an autoimmune disorder in which the immune system produces autoantibodies that stimulate the production of excessive thyroid hormone.

-dipsia

thirst

thym/o

thymus gland

The ____________________ is the largest gland of the endocrine system.

thyroid gland

thyr/o

thyroid gland

thyroid/o

thyroid gland

-oma

tumor

thym/oma

tumor of the thymus gland. A thymoma is a rare neoplasm of the thymus gland. Treatment includes surgical removal, radiation therapy, and chemotherapy.

- Although genetics and environmental factors, such as obesity and lack of exercise, seem significant in the development of this disease, the cause of diabetes is not always clear. Diabetes mellitus occurs in two primary forms:

type 1 and type 2. Type 1 Diabetes - Type 1 diabetes is an autoimmune disease. It is usually diagnosed in children and young adults. In type 1 diabetes, the body does not produce a sufficient amount of insulin. Like all autoimmune diseases, it requires constant monitoring and medicating. - Blood glucose levels are monitored by the patient several times a day using a glucometer to determine the amount of insulin needed to control blood sugar levels. The patient administers insulin injections as needed. Insulin injections should be administered in a different subcutaneous site each time to avoid injury to the tissues. (See Fig. 14-6.) Type 2 Diabetes - In type 2 diabetes, either the body's cells are resistant to insulin or the pancreas is deficient in producing insulin. In both cases, the body's cells do not absorb glucose, and it remains in the blood, causing hyperglycemia. - Type 2 diabetes is the most common form and is distinctively different from type 1. Its onset is typically later in life; however, it has become more prevalent in children as the incidence of obesity has increased. Risk factors include a family history of diabetes and obesity. Treatment for type 2 diabetes includes exercise, diet, weight loss, and insulin or oral antidiabetic agents, if needed. (See Table 14-6.)

hypo-

under, below

Disorders of the endocrine system are caused by

underproduction (hyposecretion) or overproduction (hypersecretion) of hormones. In general, hyposecretion is treated with drug therapy in the form of hormone replacement. Hypersecretion is generally treated with surgery.

-uria

urine

ur

urine

vol

volume