Anatomy and physiology

Question 1

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

Question 2

The endocrine system also maintains an internal state of equilibrium in the body (homeostasis) so that all body systems function effectively. The ductless glands of the endocrine system include the pituitary, thyroid, parathyroid, adrenal, pancreatic, pineal, and thymus glands and the ovaries and testes.

Question 3

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. 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. Other hormones, such as calcitonin and some pituitary gland hormones, have only one or a few target organs. In general, hormones regulate growth, metabolism, reproduction, energy level, and sexual characteristics.

Question 4

Acting in opposition; mutually opposing

Answer 4

antagonistic
ăn-TĂG-ō-nĭst-ĭk □

Question 5

Salts and minerals that conduct electrical impulses in the body
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 ones are sodium chloride, potassium, calcium, and sodium bicarbonate.

Answer 5

electrolytes
ē-LĔK-trō-līts □

Question 6

Hormone produced by pancreatic alpha cells that stimulates the liver to change stored ____ (a starch form of sugar) to glucose.
________opposes the action of insulin(uptake and storage). It is used to reverse hypoglycemic(low blood sugar) reactions in insulin shock.

Answer 6

Glycogen

The hormone
-glucagon- 2x

Question 7

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

Answer 7

glucose3x
GLOO-kōs □

Question 8

sympatho____
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 ____epinephrine are sympathomimetic hormones because they produce effects that mimic those brought about by the sympathetic nervous system

Answer 8

Mimetic
Nor

Question 9

The____ gland, or _____physis, is a 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. The pituitary gland consists of two distinct portions

Answer 9

pituitary
Hypo

Question 10

an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis). The anterior lobe, triggered by the action of the hypothalamus, produces at least six hormones. The posterior lobe stores and secretes two hormones produced by the hypothalamus: antidiuretic hormone (ADH) and oxytocin. These hormones are released into the bloodstream as needed. (See

Question 11

Thyroid Gland
The (2) thyroid gland is the largest gland of the endocrine system. An H-shaped organ located in the neck just below the larynx, this gland is composed of two large lobes that are separated by a strip of tissue called an isthmus. Thyroid hormone (TH) is the body’s major metabolic hormone. TH increases the rate of oxygen consumption and, thus, the rate at which carbohydrates, proteins, and fats are metabolized. TH is actually two active iodine-containing hormones: thyroxine (T4) and triiodothyronine (T3). T4 is the major hormone secreted by the thyroid; most T3 is formed at the target tissues by conversion of T4 to T3. Except for the adult brain, spleen, testes, uterus, and the thyroid gland itself, thyroid hormone affects virtually every cell in the body. TH also influences growth hormone and plays an important role in maintaining blood pressure. (See Table 14-2.)

Question 12

Anterior Pituitary Hormones (Adenohypophysis)
Adrenocorticotropic hormone (ACTH)
• Adrenal cortex—promotes secretion of corticosteroids, especially cortisol
• Hyposecretion is rare.
• Hypersecretion causes Cushing disease.

Question 13

Anterior pituitary, hormone Follicle-stimulating hormone (FSH)
• Ovaries—in females, stimulates egg (ova) production; increases secretion of estrogen
• Testes—in males, stimulates sperm production
• Hyposecretion causes failure of sexual maturation.
• Hypersecretion has no known significant effects.

Question 14

Anterior pituitary, hormone Growth hormone (GH) or somatotropin
• Regulates growth of bone, muscle, and other body tissues
• Increases use of fats for energy
• Hyposecretion during childhood and puberty causes pituitary dwarfism.
• Hypersecretion during childhood and puberty causes gigantism; hypersecretion during adulthood causes acromegaly.

Question 15

Anterior pituitary hormone Luteinizing hormone (LH)
• Ovaries—in females, promotes ovulation; stimulates production of estrogen and progesterone
• Testes—in males, promotes secretion of testosterone
• Hyposecretion in nursing mothers causes poor lactation.
• Hyposecretion causes failure of sexual maturation.
• Hypersecretion has no known significant effects.

Question 16

Anterior pituitary hormone Prolactin (PRL)
• Breast—in conjunction with other hormones, promotes lactation
• Hypersecretion in nursing mothers causes excessive secretion of milk (galactorrhea).

Question 17

Anterior pituitary hormone Thyroid-stimulating hormone (TSH) or thyrotropin
• Thyroid gland—stimulates secretion of thyroid hormones
• Hyposecretion in infants causes cretinism; hyposecretion in adults causes myxedema.
• Hypersecretion causes Graves disease, which results in exophthalmos

Question 18

Posterior pituitary hormone Posterior Pituitary Hormones (Neurohypophysis)
Antidiuretic hormone (ADH)
• Kidney—increases water reabsorption (water returns to the blood)
• Hyposecretion causes diabetes insipidus (DI).
• Hypersecretion causes syndrome of inappropriate antidiuretic hormone (SIADH).

Question 19

Posterior pituitary hormone Oxytocin
• Uterus—stimulates uterine contractions; initiates labor
• Breast—promotes milk secretion from the mammary glands
• Unknown

Question 20

Thyroid hormone

Calcitonin
• Regulates calcium levels in the blood in conjunction with parathyroid hormone
• Decreases the reabsorption of calcium and phosphate from bones to blood
• The most significant effects are exerted in childhood when bones are growing and changing dramatically in mass, size, and shape.
• At best, calcitonin is a weak hypocalcemic agent in adults

Question 21

Thyroid, hormone
Thyroxine (T4) and triiodothyronine (T3)
• Increases energy production from all food types
• Increases rate of protein synthesis
• Hyposecretion in infants causes cretinism; hyposecretion in adults causes myxedema.
• Hypersecretion causes Graves disease, which results in exophthalmos.

Question 22

Parathyroid Glands
The (3) parathyroid glands consist of at least four separate glands located on the posterior surface of the lobes of the thyroid gland. The only hormone known to be secreted by the parathyroid glands is parathyroid hormone (PTH). PTH helps to regulate calcium balance by stimulating three target organs: bones, kidneys, and intestines. (See Table 14-3.) Because of PTH stimulation, calcium and phosphates are released from bones, increasing concentration of these substances in blood. Thus, calcium that is necessary for the proper functioning of body tissues is available in the bloodstream. At the same time, PTH enhances the absorption of calcium and phosphates from foods in the intestine, causing a rise in blood levels of calcium and phosphates. PTH causes the kidneys to conserve blood calcium and increase the excretion of phosphates in urine.

Question 23

Parathyroid hormone (PTH)
• Bones—increases the reabsorption of calcium and phosphate from bone to blood
• Kidneys—increases calcium absorption and phosphate excretion
• Small intestine—increases absorption of calcium and phosphate
• Hyposecretion causes tetany.
• Hypersecretion causes osteitis fibrosa cystica.

Question 24

Adrenal Glands
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. 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.

Question 25

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.

Question 26

Adrenal cortex, hormone 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.

Question 27

Adrenal cortex hormone 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.

Question 28

Adrenal Medulla 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.

Question 29

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. (See Table 14-4, page 482.)

Question 30

Adrenal Cortex Hormones Glucocorticoids (mainly cortisol) • Body cells—promote gluconeogenesis; regulate metabolism of carbohydrates, proteins, and fats; and help depress inflammatory and immune responses • Hyposecretion causes Addison disease. • Hypersecretion causes Cushing syndrome.

Question 31

Adrenal cortex hormones Mineralocorticoids (mainly aldosterone) • Kidneys—increase blood levels of sodium and decrease blood levels of potassium in the kidneys • Hyposecretion causes Addison disease. • Hypersecretion causes aldosteronism.

Question 32

Adrenal cortex hormones Sex hormones (any of the androgens, estrogens, or related steroid hormones produced by the ovaries, testes, and adrenal cortices) • In females, possibly responsible for female libido and source of estrogen after menopause (otherwise, insignificant effects in adults) • 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.

Question 33

Adrenal Medullary Hormones Epinephrine and norepinephrine • 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 • Hyposecretion has no known significant effect. • Hypersecretion causes prolonged “fight-or-flight” reaction and hypertension.

Question 34

Pancreas The pancreas lies inferior to the stomach in a bend of the duodenum. 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 through the islets of Langerhans: glucagon, which is produced by the alpha cells, and insulin, which is produced by the beta cells. Both hormones play important roles in regulating blood glucose (sugar) levels:

Question 35

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.

Question 36

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.

Question 37

Insulin and glucagon function antagonistically, so that normal secretion of both hormones ensures a blood glucose level that fluctuates within normal limits. (See Table 14-5.)

Question 38

Glucagon targets • 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) • A deficiency in glucagon may cause persistently low blood glucose levels (hypoglycemia).

Question 39

Insulin • Tissue cells—lowers blood glucose level by accelerating glucose transport into cells and the use of that glucose for energy production (glucose to glycogen) • Hyposecretion of insulin causes diabetes mellitus. • Hypersecretion of insulin causes hyperinsulinism.

Question 40

Pineal Gland The (6) pineal gland is a small organ shaped like pine cone and located deep within the brain, just behind the thalamus. Although the exact functions of this gland have not been established, there is evidence that it secretes the hormone melatonin. It is believed that melatonin may inhibit the activities of the ovaries. When melatonin production is high, ovulation is blocked, and there may be a delay in puberty.

Question 41

Thymus Gland The (7) 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 (discussed in Chapter 9, Blood, Lymphatic, and Immune Systems) and part of the endocrine system. As an endocrine gland, the thymus secretes thymosin, which plays a role in the development of the immune response in newborns. After puberty, the lymphatic tissue gradually degenerates.

Question 42

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 • Hormones from the thymus stimulate lymphocyte production. • Glucocorticoids depress the immune response and inflammation. Cardiovascular • Hormones influence heart rate, contraction strength, blood volume, and blood pressure. • Estrogen helps maintain vascular health in women. Digestive • Hormones help control digestive system activity. • Hormones influence the motility and glandular activity of the digestive tract, gallbladder secretion, and secretion of enzymes from the pancreas. • Insulin and glucagon adjust glucose metabolism in the liver.

Question 43

Female Reproductive • Hormones play a major role in the development and function of the reproductive organs. • Hormones influence the menstrual cycle, pregnancy, parturition, and lactation. • Sex hormones play a major role in the development of secondary sex characteristics. • The hormone oxytocin triggers contraction of the pregnant uterus and later stimulates the release of breast milk. Integumentary • Hormones regulate the activity of the sebaceous glands, the distribution of subcutaneous tissue, and hair growth. • Hormones stimulate melanocytes to produce skin pigment. • The hormone estrogen increases skin hydration. Male Reproductive • Hormones play a major role in the development and function of the reproductive organs. • Sex hormones play a major role in the development of secondary sex characteristics. • Hormones play a role in sexual development, sex drive, and sperm production.

Question 44

Musculoskeletal • Hormone secretions influence blood flow to muscles during exercise. • Hormones influence muscle metabolism, mass, and strength. • Hormones from the pituitary and thyroid glands and the gonads stimulate bone growth. • Hormones govern blood calcium balance. Nervous • Several hormones play an important role in the normal maturation and function of the nervous system. Respiratory • Hormones stimulate red blood cell production when the body experiences a decrease in oxygen. • Epinephrine influences ventilation by dilating the bronchioles; epinephrine and thyroxine stimulate cell respiration. Urinary • Hormones regulate water and electrolyte balance in the kidneys.

Question 45

adren/o adrenal glands adren/o/megaly (ăd-rēn-ō-MĔG-ă-lē): enlargement of adrenal glands -megaly: enlargement adrenal/o adrenal/ectomy (ăd-rē-năl-ĔK-tō-mē): ectomy: excision, removal

Question 46

calc/o calcium hyper/calc/emia (hī-pĕr-kăl-SĒ-mē-ă): hyper-: excessive, above normal -emia: blood condition

Question 47

crin/o secrete endo/crin/o/logy (ĕn-dō-krĭn-ŎL-ō-jē): endo-: in, within -logy: study of Endocrinology is the branch of medicine concerned with endocrine glands and hormones.

Question 48

gluc/o sugar, sweetness gluc/o/genesis (gloo-kō-JĔN-ĕ-sĭs): -genesis: forming, producing, origin glyc/o hypo/glyc/emia (hī-pō-glī-SĒ-mē-ă): hypo-: under, below -emia: blood condition Common causes of hypoglycemia include too much insulin, excessive secretion of insulin by the islet cells of the pancreas, and dietary deficiency. glycos/o glycos/uria (glī-kō-SŪ-rē-ă):

Question 49

home/o same, alike home/o/stasis (hō-mē-ō-STĀ-sĭs): -stasis: standing still

Question 50

kal/i potassium (an electrolyte) kal/emia (kă-LĒ-mē-ă): -emia: blood condition

Question 51

pancreat/o pancreas pancreat/o/tomy (păn-krē-ă-TŎT-ō-mē): -tomy: incision

Question 52

parathyroid/o parathyroid glands parathyroid/ectomy (păr-ă-thī-royd-ĔK-tō-mē): -ectomy: excision, removal

Question 53

thym/o thymus gland thym/oma (thī-MŌ-mă): -oma: tumor A thymoma is a rare neoplasm of the thymus gland. Treatment includes surgical removal, radiation therapy, and chemotherapy

Question 54

thyr/o thyroid gland thyr/o/megaly (thī-rō-MĔG-ă-lē): -megaly: enlargement thyroid/o hyper/thyroid/ism (hī-pĕr-THĪ-royd-ĭzm): hyper-: excessive, above normal

Question 55

toxic/o poison toxic/o/logist (tŏks-ĭ-KŎL-ō-jĭst): -logist: specialist in the study of Toxicologists study the effects of toxins and antidotes used for treatment of toxic disorders.

Question 56

Suffixes -crine secrete endo/crine (ĔN-dō-krĭn): endo-: in, within

Question 57

dipsia thirst poly/dipsia (pŏl-ē-DĬP-sē-ă): poly: many, much Polydipsia is one of the three “polys” (along with polyphagia and polyuria) associated with diabetes.

Question 58

gen forming, producing, origin andr/o/gen (ĂN-drō-jĕn): andr/o: male

Question 59

toxic pertaining to poison thyr/o/toxic (thī-rō-TŎKS-ĭk): thyr/o: thyroid gland

Question 60

uria urine glycos/uria (glī-kō-SŪ-rē-ă): glycos: sugar, sweetness

Question 61

Prefixes eu- good eu/thyr/oid (ū-THĪ-royd): thyr/o: thyroid gland -oid: resembling

Question 62

exo- outside exo/crine (ĔKS-ō-krĭn): -crine: secrete Exocrine glands (sweat and oil glands) secrete their products outwardly through excretory ducts.

Question 63

poly many poly/uria (pŏl-ē-Ū-rē-ă): -uria: urine Some causes of polyuria are diabetes, use of diuretics, excessive fluid intake, and hypercalcemia.