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Chapter 11.

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1 Chapter 11

2 Objectives Distinguish between endocrine and exocrine glands and define the terms hormone and prostaglandin. Identify and locate the primary endocrine glands and list the major hormones produced by each gland. Describe the mechanisms of steroid and non-steroid hormone action. Explain how negative and positive feedback mechanisms regulate the secretion of endocrine hormones. Explain the primary mechanisms of endocrine disorders. identify the principal functions of each major endocrine hormone and describe the conditions that may result from hyposecretion or hypersecretion. Define diabetes insipidus, diabetes mellitus, gigantism, goiter, cretinism, and glycosuria.

3 Quick Outline MECHANISMS OF HORMONE ACTION PARATHYROID GLANDS
ADRENAL GLANDS Nonsteroid Hormones Adrenal Cortex Steroid Hormones Adrenal Medulla REGULATION OF HOFIMONE SECRETION Adrenal Abnormalities PANCFIEATIC ISLETS MECHANISMS OF ENDOCFIINE DISEASE FEMALE SEX GLANDS MALE SEX GLANDS PROSTAGLANDINS THYMUS PITUITAFIY GLAND PLACENTA Anterior Pituitary Gland Hormones PINEAL GLAND Posterior Pituitary Gland Hormones OTHER ENDOCRINE STRUCTURES HYPOTHALAMUS THYROID GLAND

4 Mechanisms of Hormone Action
Endocrine glands secrete chemicals (hormones) into the blood (Figure 11-1) Hormones perform general functions of communication and control but a slower, longer-lasting type of control than that provided by nerve impulses Cells acted on by hormones are called target organ cells Page(s)

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6 Mechanisms of Hormone Action
Nonsteroid hormones (first messengers) bind to receptors on the target cell membrane, triggering second messengers to affect the cell’s activities (Figure 11-2) Page(s)

7 Mechanisms of Hormone Action
Steroid hormones bind to receptors within the target cell nucleus and influence cell activity by acting on DNA (Figure 11- 3) Page(s)

8 Regulation of Hormone Secretion
Hormone secretion is controlled by homeostatic feedback Negative feedback—mechanisms that reverse the direction of a change in a physiological system (Figure 11-4) Positive feedback—(uncommon) mechanisms that amplify physiological changes Page(s)

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10 Mechanisms of Endocrine Disease
(Table 11-1) Hypersecretion—secretion of an excess of hormone Hyposecretion—insufficient hormone secretion Target cell insensitivity produces results similar to hyposecretion Endocrinologists have developed many different strategies for treatment (e.g., surgery and hormone therapy) Page(s) 351

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14 Prostaglandins Prostaglandins (PGs) are powerful substances found in a wide variety of body tissues PGs are often produced in a tissue and diffuse only a short distance to act on cells in that tissue Several classes of PGs include prostaglandin A (PGA), prostaglandin E (PGE), and prostaglandin F (PGF) PGs influence many body functions, including respiration, blood pressure, gastrointestinal secretions, and reproduction Page(s) 351

15 Pituitary Gland (Figure 11-6)
Page(s) 354

16 Pituitary Gland Anterior pituitary gland (adenohypophysis)
Names of major hormones Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Growth hormone (GH) Prolactin (lactogenic hormone) Page(s)

17 Pituitary Gland Functions of major hormones
TSH—stimulates growth of the thyroid gland; also stimulates it to secrete thyroid hormone ACTH—stimulates growth of the adrenal cortex and stimulates it to secrete glucocorticoids (mainly cortisol) FSH—initiates growth of ovarian follicles each month in the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation; FSH also stimulates estrogen secretion by developing follicles; stimulates sperm production in the male Page(s)

18 Pituitary Gland Functions of major hormones
LH—acts with FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum; causes interstitial cells in the testes to secrete testosterone in the male Page(s)

19 Pituitary Gland Functions of major hormones
LH—acts with FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum; causes interstitial cells in the testes to secrete testosterone in the male Page(s)

20 Pituitary Gland Functions of major hormones
GH—stimulates growth by accelerating protein anabolism; also accelerates fat catabolism and slows glucose catabolism; by slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia) Hypersecretion during childhood results in gigantism and during adulthood results in acromegaly Hyposecretion during childhood results in pituitary dwarfism Page(s)

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23 Pituitary Gland Functions of major hormones
Prolactin or lactogenic hormone—stimulates breast development during pregnancy and secretion of milk after the delivery of the baby Page(s)

24 Pituitary Gland Posterior pituitary gland (neurohypo- physis)
Names of hormones Antidiuretic hormone (ADH) Hyposecretion causes diabetes insipidus, characterized by excessive volume of urine Oxytocin Page(s)

25 Pituitary Gland Functions of hormones
ADH—accelerates water reabsorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion Oxytocin—stimulates the pregnant uterus to contract; may initiate labor; causes glandular cells of the breast to release milk into ducts Page(s)

26 Hypothalamus Actual production of ADH and oxytocin occurs in the hypothalamus After production in the hypothalamus, hormones pass along axons into the pituitary gland The secretion and release of posterior pituitary hormones is controlled by nervous stimulation The hypothalamus controls many body functions related to homeostasis (temperature, appetite, and thirst) Page(s) 344, 355

27 Thyroid Gland (Figure 11-7)
Page(s) 356

28 Thyroid Gland Thyroid hormone—thyroxine (T4) and triiodothyronine (T3)
Names of hormones Thyroid hormone—thyroxine (T4) and triiodothyronine (T3) Calcitonin Functions of hormones Thyroid hormones—accelerate catabolism (increase the body’s metabolic rate) Calcitonin—decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood Page(s)

29 Thyroid Gland Thyroid Hormones are stored in colloid in thyroid follicles Page(s) 356

30 Thyroid Gland Hyperthyroidism (hypersecretion of thyroid hormones) increases meta- bolic rate Characterized by restlessness and exophthalmos (protruding eyes) Graves’ disease is an inherited form of hyperthyroid-ism Page(s) 357

31 Thyroid Gland Hypothyroidism (hyposecretion of thyroid hormones)
May result from different conditions Simple goiter—painless enlargement of thyroid caused by dietary deficiency of iodine Page(s) 357

32 Thyroid Gland Hypothyroidism (hyposecretion of thyroid hormones)
Hyposecretion during early development may result in cretinism (retardation) and during adulthood in myxedema (characterized by edema and sluggishness) Page(s) 358

33 Parathyroid Glands (Figure 11-7)
Name of hormone— parathyroid hormone (PTH) Function of hormone— increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood Page(s) 356, 358

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35 Adrenal Glands (Figure 11-13)
Page(s) 359

36 Adrenal Glands Names of hormones (corticoids) Adrenal cortex
Glucocorticoids (GCs)—chiefly cortisol Mineralocorticoids (MCs)—chiefly aldosterone Sex hormones—small amounts of male hormones (androgens) secreted by adrenal cortex of both sexes Page(s)

37 Adrenal Glands Three cell layers (zones)
Outer layer—secretes mineralocorticoids Middle layer—secretes glucocorticoids Inner layer—secretes sex hormones Mineralocorticoids—increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium Page(s)

38 Adrenal Glands Functions of glucocorticoids
Help maintain normal blood glucose concentration by increasing gluconeogenesis—the formation of “new” glucose from amino acids produced by the breakdown of proteins, mainly those in muscle tissue cells; also the conversion to glucose of fatty acids produced by the breakdown of fats stored in adipose tissue cells Play an essential part in maintaining normal blood pressure—make it possible for epinephrine and norepinephrine to maintain a normal degree of vasoconstriction, a condition necessary for maintaining normal blood pressure Page(s) 360

39 Adrenal Glands Act with epinephrine and norepinephrine to produce an antiinflammatory effect, to bring about normal recovery from inflammations of various kinds Produce anti-immunity, anti-allergy effect; bring about a decrease in the number of lymphocytes and plasma cells and therefore a decrease in the amount of antibodies formed Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress; high blood concentration of glucocorticoids, in turn, brings about many other stress responses (Figure 11-14) Page(s) 360

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41 Adrenal Glands Adrenal medulla
Names of hormones—epinephrine (adrenaline) and norepinephrine Functions of hormones—help the body resist stress by intensifying and prolonging the effects of sympathetic stimulation; increased epinephrine secretion is the first endocrine response to stress Page(s)

42 Adrenal Glands Adrenal abnormalities
Hypersecretion of glucocorticoids causes Cushing syndrome: moon face, hump on back, elevated blood sugar levels, frequent infections Page(s)

43 Adrenal Glands Adrenal abnormalities
Hypersecretion of adrenal androgens may result from a virilizing tumor and cause masculinization of affected women Hyposecretion of cortical hormones may result in Addison disease: muscle weakness, reduced blood sugar, nausea, loss of appetite, and weight loss Page(s)

44 Pancreatic Islets (Figure 11-17)
Page(s) 364

45 Pancreatic Islets Names of hormones Glucagon—secreted by alpha cells
Insulin—secreted by beta cells Page(s)

46 Pancreatic Islets Functions of hormones Glucagon increases the blood glucose level by accelerating liver glycogenolysis (conversion of glycogen to glucose) Insulin decreases the blood glucose by accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells Page(s) 363

47 Pancreatic Islets Type 1 results from hyposecretion of insulin
Diabetes mellitus (Figure 11-18) Type 1 results from hyposecretion of insulin Type 2 results from target cell insensitivity to insulin Glucose cannot enter cells and thus blood glucose levels rise, producing glycosuria (glucose in the urine) Page(s)

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49 Female Sex Glands The ovaries contain two structures that secrete hormones—the ovarian follicles and the corpus luteum; see Chapter 22 Effects of estrogen (feminizing hormone) Development and maturation of breasts and external genitals Development of adult female body contours Initiation of menstrual cycle Page(s) 344, 366

50 Male Sex Glands The interstitial cells of testes secrete the male hormone testosterone; see Chapter 22 Effects of testosterone (masculinizing hormone) Maturation of external genitals Beard growth Voice changes at puberty Development of musculature and body contours typical of the male Page(s) 344, 366

51 Thymus Name of hormone— thymosin
Function of hormone—plays an important role in the development and function of the body’s immune system Page(s) 344,

52 Placenta Name of hormones—chorionic gonadotropins, estrogens, and progesterone Functions of hormones—maintain the corpus luteum during pregnancy Page(s) 367

53 Pineal Gland A small gland near the roof of the third ventricle of the brain Glandular tissue predominates in children and young adults Becomes fibrous and calcified with age Called third eye because its influence on secretory activity is related to the amount of light entering the eyes Page(s) 344, 367

54 Pineal Gland Inhibits ovarian activity
Secretes melatonin, which: Inhibits ovarian activity Regulates the body’s internal clock Abnormal secretion of (or sensitivity to) melatonin may produce seasonal affective disorder (SAD) or winter depression, a form of depression that occurs when exposure to sunlight is low and melatonin levels are high Page(s) 367

55 Other Endocrine Structures
Many organs (for example, the stomach, intestines, and kidney) produce endocrine hormones The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys Fat-storing cells secrete leptin, which controls how full or hungry we feel Page(s)

56 Credits All photos and references are taken from:
Thibodeau, Gary, & Patton, Kevin. (2005). The Human body in health & disease. Mosby. ISBN:


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