1625915643-5d53d156c9525bd62bd0d3434ecdc231 (843955), страница 97
Текст из файла (страница 97)
LH stimulates testosterone synthesis by the Leydig cells of thetestes, whereas testosterone and FSH are required for spermatogenesis. FSH induces production of androgenbinding protein (ABG); androgen is concentrated in the tubules by binding to ABG, promoting spermatogenesis. Sertoli cells also produce inhibin, which, along with testosterone, exerts negative feedback effectson the axis (inhibin specifically inhibits FSH secretion). FSH, follicle-stimulating hormone; GnRH, gonadotropin-releasing hormone; LH, luteinizing hormone.Sex hormone-binding globulin (SHBG) and androgenbinding protein (ABG) are identical proteins, producedin the liver and testes, respectively.
SHBG circulates in thebloodstream and is the major carrier for testosterone and estradiol in the blood (only a small fraction of sex hormones circulates as free hormone). ABG is produced by the testes and servesto concentrate testosterone within the seminiferous tubules,where androgens promote spermatogenesis.ening of the voice are also actions of testosterone. Some ofthe actions of testosterone are dependent on its conversionto dihydrotestosterone (genital differentiation, prostatedevelopment and growth, male hair distribution, and baldness, for example), while others are direct effects oftestosterone.Review Questions367Review QuestionsCHAPTER 26: GENERAL PRINCIPLES OFENDOCRINOLOGY AND PITUITARY ANDHYPOTHALAMIC HORMONES1.
Which of the following hormones initiates its actions attarget tissues by binding to nuclear receptors?A.B.C.D.E.ACTHVasopressinEpinephrineIGF-1Thyroid hormone2. Hormonal actions are regulated by:A.B.C.D.E.affinity of receptors for the hormone.the number of receptors for the hormone.the degree of binding of hormone to plasma proteins.the concentration of hormone in the blood.All of the above.3. Vasopressin (ADH) secretion by the posterior pituitary isstimulated by:A.B.C.D.E.decreased body fluid osmolarity.decreased blood volume.atrial natriuretic peptide.ethanol.high blood pressure.4.
The hormone oxytocin:A.B.C.D.is released directly into the general circulation.is synthesized in the posterior pituitary gland.promotes uterine quiescence.has a well-established physiological role in induction andprogression of labor.E. is a 191 amino acid peptide.B.C.D.E.stimulated by high plasma T3.inhibited by high thyroxine-binding globulin (TBG).stimulated by high plasma T4.stimulated by TSH.7. In adults, hypothyroidism is associated with which of thephenotypes listed below?A.B.C.D.Hypertension, cold intolerance, diarrheaHypertension, nonpitting edema, cold intoleranceHypotension, higher than normal temperature, diarrheaHypotension, higher than normal temperature, nonpitting edemaE.
Hypotension, nonpitting edema, cold intolerance8. In the plasma, thyroid hormone:A. is present primarily in the T3 form.B. is present primarily in the T3 form and is bound toproteins.C. is completely bound to thyroxine-binding globulin(TBG).D. is present primarily in the T4 form and is mostly bound toproteins, including TBG.E.
is present only as free T3 and T4.9. Feedback regulation of thyroid hormone is illustrated by:A. high circulating levels of free T3 and T4, which elevateTRH.B. high circulating levels of free T3 and T4, which elevateTSH.C. high circulating levels of free T3 and T4, which reduceTRH.D. reduced TRH, which elevates TSH.E. reduced TSH, which elevates TRH.5. Growth hormone secretion:CHAPTER 28: ADRENAL HORMONESA.B.C.D.10.
Stimulation of the adrenal gland by ACTH has the mostdirect effect on release of:occurs in pulses, mainly during sleep.is stimulated by a specific hypothalamic neurohormone.is inhibited by somatostatin.results in synthesis of insulin-like growth factor in a varietyof target tissues.E. All of the above.CHAPTER 27: THYROID HORMONES6. Thyroid hormone secretion is:A. inhibited by elevated plasma estrogen levels.A.B.C.D.E.epinephrine.norepinephrine.cortisol.androgens.aldosterone.368Endocrine Physiology11. Which portion of the adrenal gland secretes a hormonewith anti-inflammatory actions?A.B.C.D.E.The medullaThe zona reticularisThe zona fasciculataThe zona glomerulosaNone of the above.12. Which of the following is a significant action of adrenalandrogens in females?A.B.C.D.E.Stimulation of libidoHypertrophy of sebaceous glandsDevelopment of pubic hairDevelopment of axillary hairAll of the above.13.
Aldosterone secretion by the adrenal gland is stimulatedby:A.B.C.D.E.hypokalemia.high plasma Na+ concentration.angiotensin II.atrial natriuretic peptide.All of the above.CHAPTER 29: THE ENDOCRINE PANCREAS16. Factors that stimulate insulin secretion include:A.B.C.D.E.glucagon-like peptide-1 (GLP-1).amino acids.glucose insulinotropic peptide (GIP).fatty acids.All of the above.17.
Insulin is a hypoglycemic hormone because of its abilityto:A.B.C.D.E.increase gluconeogenesis.reduce glycogen storage in muscle.increase glycogenolysis.increase GLUT1 transporters in brain tissue membranes.increase GLUT4 transporters in adipose tissue and skeletaland cardiac muscle membranes.CHAPTER 30: CALCIUM-REGULATINGHORMONES18. Decreased plasma calcium levels result in:A.B.C.D.E.reduced production of 1,25-dihydroxycholecalciferol.reduced production of 25-hydroxycholecalciferol.increased bone mineralization.increased bone resorption.increased plasma calcitonin.14.
Insulin is necessary for:19. Parathyroid hormone (PTH):A.B.C.D.E.A. is released into plasma in response to increases in plasmacalcium.B. acts at the kidneys to increase calcium reabsorption anddecrease phosphate reabsorption.C. acts at the kidneys to decrease calcium reabsorption at thedistal tubule.D. acts at the bone to increase bone mineralization.E. acts at the bone to decrease osteoclastic osteolysis.entry of glucose into tissues via the GLUT1 transporter.entry of glucose into all tissues.entry of glucose into the brain.entry of glucose into the pancreas.entry of glucose into tissues via GLUT4 transporters.15. Regulation of insulin release by increased plasma glucoseinvolves which of the following sequence of steps?A.
Entry of glucose into pancreatic β-cells through GLUT1transporters; increased ATP, which decreases K+ efflux;depolarization of the β-cell; Ca2+ influx; insulin granulereleaseB. Entry of glucose into pancreatic β-cells through GLUT1transporters; hyperpolarization of the β-cell; Ca2+ efflux;insulin granule releaseC. Entry of glucose into pancreatic β-cells through GLUT2transporters; increased ATP, which decreases K+ efflux;depolarization of the β-cell; Ca2+ influx; insulin granulereleaseD.
Entry of glucose into pancreatic β-cells through GLUT2transporters; hyperpolarization of the β-cell; Ca2+ efflux;insulin granule releaseE. Entry of glucose into pancreatic β-cells through GLUT4transporters; depolarization of the β-cell; Ca2+ influx;insulin granule release20. Primary hyperparathyroidism is often associated with:A.B.C.D.E.development of renal calculi.bone pain.constipation.fatigue.All of the above.CHAPTER 31: HORMONES OF THEREPRODUCTIVE SYSTEM21. During fetal development, the formation of male genitaliais directly stimulated by:A.
testosterone.B. dihydrotestosterone.Review QuestionsC. dehydroepiandrosterone.D. androstenedione.E. estrone.22. The pubertal growth spurt is mainly stimulated by thehormone:A.B.C.D.E.calcitonin.vitamin D.estradiol.testosterone.dihydrotestosterone.23. Conversion of androgens to estradiol by the folliculargranulosa cells is stimulated by the hormone:A.B.C.D.E.LH.FSH.oxytocin.growth hormone.prolactin.36924.
During the prepubertal period, germ cells in women arearrested at which stage of gametogenesis?A.B.C.D.E.OogoniaPrimary oocyteSecondary oocyteOvumZygote25. The hormone inhibin has direct negative feedback effectson the release of:A.B.C.D.E.prolactin.FSH.LH.testosterone.GnRH.This page intentionally left blankAnswersSection 1: Cell Physiology, Fluid Homeostasis, andMembrane Transport1. B. Antipyrine diffuses throughout the body water and can be usedto measure the volume of total body water; inulin does not entercells and can be used to measure the extracellular fluid (ECF)volume. Using the indicator-dilution formula, the amount of indicator injected divided by the plasma concentration will result in thevolume of the compartment. By this method, the total water (indicated by antipyrine) is 36 L, and the ECF (indicated by inulin) is12 L; the intracellular fluid (ICF) is 24 L. The ECF (12 L) is onefourth plasma (3 L) and three-fourths interstitial fluid (ISF) (8 L).2.
D. The Starling forces favoring movement out of the capillaries arethe capillary hydrostatic pressure (HPc) and interstitial oncotic pressure (πi), while the forces favoring movement into the capillaries arethe interstitial hydrostatic pressure (HPi) and capillary oncotic pressure (πc). Thus, (30 + 8) − (3 + 28) = 7 mm Hg out of thecapillary.3. D.
Water will distribute through all compartments, and thus, bothECF and ICF volumes will increase. With the additional volume, theosmolarity of the compartments will decrease.4. C. Voltage-gated channels are highly selective, and gating is dependent on membrane voltage.5. D. The basolateral Na+/K+ ATPase, or “sodium pump,” uses primaryactive transport to pump three sodium ions out of cells in exchangefor two K+ ions. The low intracellular Na+ concentration facilitatesapical sodium entry down its concentration gradient through severaldifferent secondary active transport symporters (e.g., Na+-aminoacid, Na+-glucose) and antiporters (e.g., Na+/Ca2+, Na+/H+).6.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
