The endocrine system consists of glands that secrete hormones directly into the bloodstream to regulate distant target organs and tissues. There are three main types of hormones: steroid hormones like estrogen and testosterone which are lipid-soluble and pass through cell membranes to activate nuclear receptors; peptide hormones like insulin which are water-soluble and bind to cell surface receptors; and amine hormones like epinephrine which also bind to cell surface receptors. Hormones work through concentration-dependent effects and can have synergistic, permissive, or antagonistic interactions with each other to regulate various physiological processes in the body.

1. Endocrine System

3. Hormone is a chemical messenger secreted by one endocrine gland or cell into the bloodstream and targeted toward cells in another organ. - specificity - receptor - distribution

4. Chemical Identity of Hormones Steroid hormones 2) Biogenic amines 3) Peptide hormones

5. 1) Steroid hormones Estrogens Progesterone Androgens glucocorticoids aldosterone - derived from cholesterol

6. 2) Biogenic amines Epinephrine Norepinephrine Dopamine Serotonin Melatonin thyroid hormones Synthesized from amino acids

7. Peptide hormones Hypothalamic hormones Pituitary hormones Pancreatic hormones GI hormones - are peptides

8. Water Solubility and Membrane Permeability Steroid + thyroid hormones All other hormones Hydrophobic Membrane-permeable Hydrophilic Membrane-impermeable

11. Effects after hormones bind to their receptors 1) Synthesis of new proteins (enzymes) 2) Alterations of activities of proteins that are already present

12. Effects of Hormone Concentration

13. Effects of Hormone Concentration

14. Hormone Deactivation Hormones have short half-life (< 2 min) in the plasma.

15. Hormone Interactions Synergistic effects Two hormones act together to produce an effect that is greater than the sum of their separate effects. Permissive effects Only in the presence of one hormone, the target organ responds to a second hormone. Antagonistic effects One hormone opposes the action of another hormone.

16. 1) ADH Kidneys blood vessels reducing urine output vasoconstriction 2) Oxytocin Uterus, mammary glands, Labor contractions milk ejection Hormone Target Organ Principal Effects Posterior Pituitary

17. 1) FSH Ovaries and Testes follicle/egg or sperm development (Follicle-Stimulating Hormone) 2) LH Ovaries and testes Ovulation/growth of corpus luteum (Luteinizing Hormone) 3) TSH Thyroid gland Growth of thyroid gland Secretion of thyroid hormone (Thyroid-Stimulating Hormone) Hormone Target Organ Principal Effects Anterior Pituitary

18. Hormone Target Organ Principal Effects Anterior Pituitary 4) ACTH Adrenal cortex Growth of adrenal cortex (Adrenocorticotropic Hormone) secretion of glucocorticoids 5) PRL Mammary gland milk synthesis Testes enhance secretion of testosterone (Prolactin)

19. Hormone Target Organ Principal Effects Anterior Pituitary 6) GH Most tissues tissue/organ growth, cell mitosis and differentiation (Growth hormone or somatotropin)

20. Hypothalamus hormones

21. Hormone Target Organ Principal Effects Hypothalamus 1) TRH Pituitary Promotes TSH and PRL Thyrotropin-releasing hormone 2) CRH Pituitary Promotes ACTH Corticotropin-releasing hormone 3) GnRH Pituitary Promotes FSH/LH Gonadotropin-releasing hormone 4) PRF Pituitary Promotes PRL secretion Prolactin-releasing factor secretion secretion secretion

22. Hormone Target Organ Principal Effects Hypothalamus 5) PIF Pituitary Inhibits PRL secretion Prolactin-inhibiting factor Dopamine 6) GHRH Pituitary Promotes GH secretion Growth hormone-releasing hormone 7) GHIH Pituitary Inhibits GH/TSH secretion Growth hormone-inhibiting hormone somatostatin

23. Hormone Target Organ Principal Effects Pineal Gland 1) Melatonin Brain Regulate timing of puberty; influence mood 2) Serotonin Brain Regulate timing of puberty; influence mood

24. Thymus Hormone Target Organ Principal Effects Thymopoietin/ T lymphocytes Promote T lymphocyte Thymosins development/ activation

25. 1) Triiodothyronin (T3) Stimulate Na + -K + pumps, metabolic rate, heat production, alertness, protein synthesis, fetal and childhood growth, and CNS development Most tissues 2) Throxin (T4) Thyroid Gland Hormone Target Organ Principal Effects 3) Calcitonin Osteoblasts Stimulates calcium deposition and ossification; reduces blood calcium concentration

26. Parathyroid Gland Hormone Target Organ Principal Effects PTH Stimulates calcium absorption and retention; promotes bone resorption; elevates blood calcium concentration Small intestine, Kidneys, and Osteoclasts Parathyroid hormone

27. Adrenal Gland

28. Adrenal Medulla Hormone Target Organ Principal Effects Complement action of sympathetic nervous system 2) Norepinephrin 1) Epinephrin 3) Dopamine Most tissues

29. Adrenal Cortex Hormone Target Organ Principal Effects 1) Aldosterone Kidneys Promotes Na + retention and K + excretion; maintains blood pressure and volume 2) Glucocorticoids Most tissues Cortisol/Corticosterone Promote fat and protein catabolism, gluconeogesis, stress resistance, and tissue repair; inhibit inflammation

30. Adrenal Cortex Hormone Target Organ Principal Effects 3) Androgen Bone, muscle, Integument, many other organs Stimulate growth of pubic and axillary hair in both sexes; stimulate libido; negligible effcts in males compared to teststerone from testes

31. Pancreatic Islets Hormone Target Organ Principal Effects 1) Glucagon Primarily liver Stimulates glycogen and fat hydrolysis, mobilization of glucose and fatty acids, and gluconeogenesis 2) Insulin Most tissues Promotes glucose and amino acid uptake and synthesis of glycogen, fat, and protein

32. The Ovaries Hormone Target Organ Principal Effects Estradiol Estragen Ovaries, uterus, mammary glands, brain, many other tissues Regulates egg production; stimulates adolescent growth; promotes development of female secondary sex characteristics; prepares mammary glands for lactation; prepares uterus for pregnancy

33. The Ovaries Hormone Target Organ Principal Effects Progesterone Ovaries, uterus, mammary glands, many other tissues Stimulates mammary development in puberty and pregnancy; prepares uterus for pregnancy Inhibin Anterior pituitary Suppresses FSH secretion

34. The Testes Hormone Target Organ Principal Effects Testosterone Most Tissues Regulates sperm production; promotes development of male reproductive system and physique; stimulates adolescent growth, libido, and sexual behavior

35. Heart Hormone Target Organ Principal Effects ANF Kidneys Increases Na + excretion and urine output; lowers blood pressure

36. Kidneys Hormone Target Organ Principal Effects Calcitriol Erythropoietin Renin Intestines Red Bone marrow angiotensinogen Increase absorption of calcium Stimulate RBC production Stimulate production of angiotensin I

37. Liver Hormone Target Organ Principal Effects Angiotensi-nogen Blood vessels, adrenal cortex, hypothalamus Stimulates vasoconstriction, aldosterone secretion, and thirst Erythropoietin

38. GI tract Hormone Target Organ Principal Effects Gastrin Secretin CCK (cholecystokinin) GIP (gastric inhibitory peptide) GI tract and its accessory glands Coordinate secretion and motility in digestion

39. Placenta Hormone Target Organ Principal Effects Estrogen Progesterone Maternal and fetal tissues Promotes fetal growth; regulate pregnancy; prepare mammary glands for lactation

40. Exercise

41. 11. Digestion is a process to ___. A. take food into the mouth B. take absorbable nutrients into blood stream C. break ingested food into absorbable forms D store food in the digestive tract

42. W2. Which of the following forms of nutrients cannot be directly absorbed into blood without digestion? A. Proteins B. fatty acids C. vitamin A D. glucose

43. 33. The primary dietary carbohydrates are starch, which are ____. A. Monosaccharides B. polymers of glucose C. polymers of amino acids D. polymers of fatty acids

44. 44. Fats or triglycerides ___. A. can be absorbed without digestion B. are digested into monoglycerides and fatty acids, then absorbed in the small intestine C. are digested into glucose, then absorbed in the small intestine D. are digested into amino acids, then absorbed in the small intestine

45. 55. Which of the following is not secreted by gastric glands? A. pepsinogen B. trypsinogen C. HCl D. intrinsic factor

46. 66. Which of the following is not a function of gastric acid? A. activating pepsinogen. B. digesting connective tissues in the ingested food C. destroying ingested pathogens D. activating pancreatic enzymes

47. 77. Intrinsic factor has the function of ___? A. activating pepsinogen B. helping absorb vitamin B12 C. helping absorb vitamin B6 D. activating pancreatic enzymes

48. 88. Pepsinogen is able to digest ___. A. proteins B. fats C. starch D. none of the above

49. 99. Food digestion is completed primarily in ____. A. stomach B. small intestine C. large intestine

50. 110. Gastric motility and secretion is ____. A. inhibited when food is ingested into the mouth B. stimulated when food enters the stomach C. strongly stimulated after chyme have entered the small intestine

51. 111. Bile is produced by ____. A. hepatocytes B. gallbladder C. pancreas D. small intestine

52. 112. Bile salts are needed for digestion and absorption of ____. A. carbohydrates B. proteins C. fats D. minerals

53. 113. Which component of bile is reabsorbed via enterohepatic circulation? A. bile salts B. bile pigments C. cholesterol D. minerals

54. 114. Pancreatic juice is ____. A. acidic (low pH) B. basic (high pH) C. neutral

55. 115. Which of the following cannot be digested and absorbed by human pancreatic enzymes? A. starch B. proteins C. fats D. cellulose

56. 116. Bile and pancreatic juice are released into duodenum when ___. A. chyme is not present in duodenum B. cholecystokinin is secreted by duodenal mucosa C. hepatopancreatic sphincter constricts D. gallbladder relaxes

57. 117. Pancreatic zymogens are ___. A. active when stored in pancreatic duct B. activated after being released into duodenum

58. 118. Proteins and carbohydrates can be digested into amino acids and glucose by ___. A. pancreatic enzymes alone B. pancreatic enzymes plus brush border enzymes C. brush border enzymes alone

59. 119. Which of the following is not a hormone? A. gastrin B. cholecystokinin C. secretin D. intrinsic factor

60. 220. Which type of the movement of the small intestine can push chyme towards the large intestine? A. peristalsis B. segmentation C. both peristalsis and segmentation

61. 221. Which of the following is a function of gastrin? A. to stimulate the secretion of HCl and pepsinogen B. to inhibit gastric motility C. to inhibit motility of the large intestine

62. 222. The functions of cholecystokinin include ___. A. to stimulate constriction of gallbladder B. to stimulate relaxation of hepatopanreatic sphincter C. to inhibit gastric secretion of motility D. all of the above

63. 223. Bacterial flora ____. A. are present primarily in small intestine B. synthesize vitamins C. are harmful to human health

64. 224. The large intestine primarily absorbs ___. A. glucose B. fatty acids C. amino acids D. water

65. 225. Glucose is taken into intestinal epithelial cells directly by ____. A. Na + -K + ATPase B. sodium-dependent glucose transporters C. potassium-dependent glucose transporters D. all of the above

66. 226. Emulsification is required to complete digestion of ___. A. fats B. proteins C. carbohydrates D. water

67. 227. Hunger and satiety are regulated by ____. A. the feeding center and satiety center at hypothalamus B. cholecystokinin C. appetite-stimulating hormones released by adipocytes D. all of the above

68. 228. Which of the following nutrients is more often used to produce ATP? A. glucose B. fats C. proteins D. vitamins

69. 229. Which of the following can be stored in human body? A. ATP B. Glucose C. Glycogen and fats D. All of the above

70. 330. Which of the following fuel do neurons normally use? A. glucose B. amino acids C. fatty acids

71. 31. Absorption of blood glucose by most tissue cells depends on ____. A. insulin B. insulin receptors C. both of the above

72. 332. During absorptive state, ____. A. blood glucose is absorbed by all tissue cells B. excessive blood glucose is converted to glycogen or fat C. both of the above take place

73. 333. Glycogen is synthesized and stored primarily in ____. A. liver B. kidneys C. neurons

74. 34. Gluconeogenesis is a process that ____. A. glucose is synthesized from fats or amino acids B. occurs normally during absorptive state when blood glucose is abundant C. glycogen is hydrolyzed into glucose

75. 335. During postabsorptive state, ____. A. blood glucose comes from glycogen and fats. B. blood insulin level is high C. blood glucagon is low D. all of the above take place

76. 336. In which temporal order (first to last), are the following nutrients used to produce ATP when food is not available. A. Glycogen --- fats --- skeletal muscle proteins --- cardiac muscle proteins B. skeletal muscle proteins --- glycogen --- fats --- cardiac muscle proteins C. fats --- skeletal muscle proteins --- glycogen --- cardiac muscle proteins D. cardiac muscle proteins --- skeletal muscle proteins --- fats --- glycogen

77. 337. Body heat is produced during ___. A. synthesis of ATP B. consumption of ATP C. both of the above

78. 338. Thermoregulation center is located in ___. A. medulla oblongata B. hypothalamus C. spinal cord D. cerebral cortex

79. 339. The body heat can be lost via ___. A. conduction B. radiation C. evaporation D. all of the above

80. 440. The sex of an individual is determined by ____. A. sex chromosomes B. primary sex organs C. secondary sex organs D. secondary sex characteristics

81. 441. Sperm cells are produced in ____. A. seminiferous tubules B. epididymus C. seminal vesicles D. vas differens

82. 442. Sperm cells are stored in ____. A. seminiferous tubules B. epididymus C. seminal vesicles D. vas defferens

83. 443. Semen contains ___. A. spermatozoan B. fructose C. prostaglandins D. all of the above

84. 444. Sperm cells ___. A. start to migrate towards uterus immediately after being ejaculated into vagina B. are not able to fertilize an egg without capacitation C. can all find the egg

85. 445. In which part of the female reproductive tract is an egg usually fertilized by a sperm cell? A. uterus B. vagina C. one third of uterine tube that is proximal to the uterus D. one third of uterine tube that is distal to the uterus

86. 446. During which of the following period does a sexual intercourse have the maximum chance of resulting in pregnancy? A. starting at 48 hours before ovulation and ending at 14 hours after ovulation B. starting at 48 hours before ovulation and ending at 24 hours after ovulation C. starting at 48 hours before ovulation and ending at 48 hours after ovulation D. starting at 48 hours before ovulation and ending at 72 hours after ovulation

87. 447. Which of the following statement is incorrect? A. Only one egg is released by two ovaries in each ovarian cycle B. Ovulation is triggered by a sudden increase of blood FSH level at day 14 C. FSH stimulates the development of follicles

88. 448. Which of the following statements about corpus luteum is incorrect ? A. Corpus luteum normally secrets progesterone and estrogen B. Corpus luteum secrets progesterone and estrogen for only ~10 days, then undergo degeneration, no matter if the egg is fertilized or not. C. Corpus luteum is formed after the oocyte is ovulated.

89. 449. Which of the following statement about uterus is incorrect? A. The growth and secretion of uterus depends on progesterone B. The uterus harbors embryo C. The uterus secrets nutrients D. The uterus does not contract at labor.

90. 550. The pH of vagina is usually ___. A. low (acidic) B. high (basic) C. neutral

91. 551. Which of the following statements about HCG is correct? A. HCG is secreted by ovaries. B. HCG is found in blood 8-10 days after fertilization C. HCG inhibits the secretion of progesterone from corpus luteum D. HCG stimulates the development of follicles.

92. 552. In which of the following events, are the chemical messengers transported by the blood? A. endocrine B. paracrine C. autocrine D. synaptic communication

93. 553. Hormones fall into the following chemical classes except ____. A. steroids B. biogenic amines C. fatty acids D. peptides

94. 554. Which of the following hormone classes has their receptors located in the nucleus? A. steroid hormones B. peptide hormones C. biogenic amine hormones (except thyroid hormones)

95. 555. Which of the following hormone classes stimulates synthesis of new proteins? A. steroid hormones B. peptide hormones C. biogenic amine hormones (except thyroid hormones)

96. 556. Long-term exposure to high levels of a hormone causes ____ in the number of receptors and sensitivity to the hormone A. a decrease B. an increase C. no change

97. 557. Which of the following statements is correct? A. Most hormones remain active for several hours after being released into the blood. B. About 50% of most hormones are deactivated a couple of minutes after being released into the blood. C. Hormones are primarily deactivated in muscles.

98. 558. Which of the following hormones is not secreted by pituitary? A. luteinizing hormone (LH) B. thyrotropin releasing hormone (TRH) C. adrenocorticotropic hormone (ACTH) D. growth hormone (GH)

99. 559. Which of the following hormones is synthesized in hypothalamus and secreted from pituitary? A. antidiuretic hormone B. prolactin C. follicle-stimulating hormone D. growth hormone

100. 660. Which of the following hormones stimulates gluconeogenesis ? A. insulin B. vasopressin C. glucagon D. gastrin

101. 661. Which of the following hormones has the strongest stimulatory effect on metabolic rate or heat production? A. thyroid hormone B. ADH C. Aldosterone D. oxytocin

102. 662. Which of the hormone stimulates uterine labor contractions? A. thyroid hormone B. ADH C. Aldosterone D. oxytocin

103. 663. Adrenal medulla secrets ____. A. catecholamines B. glucocorticoids C. aldosterone D. androgen