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The cellular action of hormones is dependent on the concentration of hormone in the blood, as well as the number and affinity ofhormone receptors in the cell or on the cell membrane. In addition,some hormones (particularly lipophilic hormones such as steroids)are carried in the blood by binding proteins, and it is specifically thefree fraction of hormones in the blood that is available for bindingby cellular receptors.3. B. Vasopressin promotes increased water absorption by the kidney,and its release is stimulated by decreased blood volume, increasedbody fluid osmolality, and decreased blood pressure.4. A.
Oxytocin, a 9 amino acid peptide, is released directly intothe general circulation by the posterior pituitary gland but issynthesized in the paraventricular and supraoptic nuclei ofthe hypothalamus. It is carried by axonal transport to nerveendings in the posterior pituitary. Its actions include milk expulsionduring breastfeeding and uterine contraction, although aphysiological role in induction or progression of labor is notwell-established.5. E.
Growth hormone is released by the anterior pituitary somatotrophs, with several pulses occurring during sleep, as well as a basallevel of secretion. Its release is stimulated by hypothalamic growthhormone–releasing hormone and inhibited by somatostatin. At the6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.375tissues, it acts by stimulating the synthesis of insulin-like growthfactor.E.
Pituitary thyroid-stimulating hormone (TSH) is a primary stimulus for thyroid hormone (TH) release.E. Hypothyroidism in adults results in myxedema, which is associated with nonpitting edema, hypotension, fat deposition, cold intolerance, and depression, among other symptoms.D. Both T3 and T4 are released from the thyroid gland, but 20 timesthe amount of T4 is released compared to T3.
Most of the T3 and T4is bound to proteins including albumin and thyroxine-bindingglobulin.C. Feedback control of TH production is illustrated by elevatedcirculating free T3 and T4, which reduces both pituitary thyroidstimulating hormone (TSH) and hypothalamic thyrotropinreleasing hormone (TRH), resulting in reduced TH production.C. Cortisol synthesis and release by the adrenal cortex is regulatedby the anterior pituitary hormone ACTH. Although ACTH isrequired for synthesis of all adrenal steroids, androgen and aldosterone synthesis and release are primarily controlled by other mechanisms.
Release of catecholamines by the adrenal medulla is controlledby the sympathetic nervous system.C. The zona fasciculata secretes cortisol, which has antiinflammatory and anti-immune effects among its many actions.The zona reticularis secretes androgens and the zonaglomerulosa secretes aldosterone. The adrenal medulla secretescatecholamines.E. Dehydroepiandrosterone and androstenedione are the majoradrenal androgens. In females, for whom the adrenal gland is theonly significant source of circulating androgens, all of the listedeffects are stimulated by these hormones.C.
The primary stimuli for aldosterone secretion by the adrenalzona glomerulosa are hyperkalemia and angiotensin II. Aldosteronesynthesis and secretion is inhibited by atrial natriuretic peptide.E. The GLUT4 transporters are the insulin-sensitive transporterspresent on most cell membranes, and insertion of these transportersfacilitates glucose entry.C. GLUT2 transporters are prominent on the pancreas, small intestine, brain, and liver and facilitate entry of glucose into the cells.In the β-cell of the pancreas, glucose metabolism increases ATPand reduces K+ efflux.
This depolarizes the β-cell, causing Ca2+influx and release of the insulin (and C-peptide).E. All of the factors listed will stimulate insulin secretion.E. Insulin has a hypoglycemic effect on the plasma by increasingGLUT4 transporters, which facilitate glucose entry into adiposetissue and cardiac and skeletal muscle, while it decreases gluconeogenesis and glycogenolysis and increases glycogen storage.D. Decreased plasma calcium concentrations will stimulate therelease of parathyroid hormone (PTH), which acts at bone toincrease resorption, releasing calcium into the blood. PTH also actsat the kidney to increase calcium reabsorption.B.
PTH is released into plasma in response to reduced plasmacalcium levels. At the kidneys it increases distal calcium reabsorption and reduces phosphate reabsorption. It also stimulates the renalconversion of 25-hydroxycholecalciferol to active vitamin D (1,25dihydroxycholecalciferol), which increases intestinal absorption ofcalcium.E. Primary hyperparathyroidism typically results from parathyroidtumors that have no negative feedback mechanisms and ultimatelyincreases plasma calcium concentrations. The elevated PTHincreases the renal conversion of 25-hydroxyvitamin D to activevitamin D, increasing intestinal calcium absorption; the reductionin fecal calcium can cause constipation.
In addition, the PTHincreases bone resorption (can cause bone pain), and the elevatedfiltered load of calcium to the kidney can cause stone formation(calculi). Overall, these symptoms can cause fatigue and general376Answersmalaise.
These “stones, bones, moans, and groans” can be characteristic symptoms of hyperparathyroidism.21. B. Differentiation of the external genitalia produces female genitalia in the absence of androgens. In the male fetus, the testes producetestosterone, which is converted to dihydrotesterone (DHT) in theprimitive genital structures. DHT stimulates formation of malegenitalia.22. C. The linear growth spurt that occurs during puberty is mainlyattributed to estradiol in both boys and girls. Estrogenic hormonesincrease linear growth of long bones and also promote the eventualclosure of the epiphyseal plates.23.
A. In developing follicles, androgen is synthesized and secreted bytheca interna cells. The conversion of androgens to estradiol by thefollicular granulosa cells is stimulated by luteinizing hormone (LH).24. B. During fetal development, germ cells in the ovaries give rise tooogonia, which proliferate and begin meiosis. They become primaryoocytes and are arrested at this stage.25. B.
FSH acts on Sertoli cells of the seminiferous tubules, stimulatingandrogen-binding protein synthesis. This protein binds testosterone, which promotes spermatogenesis. The Sertoli cells also synthesize inhibin, which inhibits follicle-stimulating hormone (FSH)secretion by the anterior pituitary gland.IndexPage numbers followed by f indicate figures; t, tables; b, boxes.AAbetalipoproteinemia, 295Absorptioncarbohydrate, 291, 293fdescription of, 8electrolytes, 296, 298in gastrointestinal tract, 246iron, 298f, 298-299lipid, 295, 296fprotein, 293-295, 294fvitamins, 299Acetoacetate, 345Acetyl coenzyme A, 307Acetylcholine, 33t, 34, 87, 253Acetylcholinesterase, 39Achalasia, 269Acidbuffering of, 231-232description of, 183excretion of, 232-234, 234ftitratable, 232-233Acid–base balanceassessments, 235description of, 183, 185importance of, 231kidneys’ role in, 185f, 236flungs’ role in, 185f, 236fAcid–base disturbancesacidosis.
See Acidosisalkalosis. See Alkalosiscalcium concentrations affected by, 347overview of, 185-186Acidemia, 185Acidophil adenoma, 318Acidosisanion gap used to differentiate, 235-236description of, 234-235metabolic, 186t, 234metabolic ketoacidosis, 238pathophysiology of, 235respiratory, 186t, 234Actin, 39, 42Action potentialscardiac, 101-102cardiac cycle initiation and, 115characteristics of, 28conduction, 28, 30-32definition of, 28endplate potentials vs., 36-37illustration of, 29finitiation of, 28“jumping” between nodes, 32phases of, 101plateau of, 101propagation of, 30, 31fActivation gates, 28Active hyperemia, 129, 130fActive transport, 14-15, 15f-16fActive ventricular filling, 115Acute altitude sickness, 191Acute glomerulonephritis, 201Acute pyelonephritis, 224Addisonian crisis, 337Addison’s disease, 337Adenomas, 318Adenosine, 33tAdenosine triphosphatedescription of, 14nervous system locations of, 33tpartially hydrolyzed, 40release of, 87Adenylyl cyclase, 18tAdrenal cortexanatomy of, 329, 331fhormones of, 329-330, 332fAdrenal glandsanatomy of, 329, 330fhistology of, 331fhormones of, 308f, 329-330Adrenal medulla, 87, 92, 329, 337, 338fAdrenarche, 334Adrenergic drugs, 171Adrenergic receptors, 91Adrenocorticotropic hormone, 310, 329-330,334Afterload, 117, 119Agonists, 16Airway resistance, 163, 170-171, 177fAirwaysanatomy of, 148, 151fdynamic compression of, during expiration,171-174intrapulmonary, 151fAldosterone, 133, 225, 336-337Alkaline tide, 276Alkalosisdefinition of, 185description of, 234-235metabolic, 186t, 234, 237, 267pathophysiology of, 237respiratory, 186t, 234“All-or-none” response, 28Alveolar air, 156-157Alveolar gas equation, 157Alveolar gases, 156-157Alveolar oxygen concentration, 147Alveolar ventilation, 156Alveolar-arterial O2 difference, 178fAlveolar-capillary membrane, 149-150Alveolar-to-systemic arterial PO2 gradient, 161Alveoli, 149-150Amino acids, 287, 345γ-Aminobutyric acid, 33tAmmonia, 232Ammoniagenesis, 197, 233Amniotic sac, 140Ampullary crest, 69Amygdala, 51α-Amylasepancreatic, 291, 293fsalivary, 271, 282, 291, 293fAnatomical dead space, 148-149Anatomical shunt, 161Androgen-binding protein, 364, 366Androstenedione, 332f, 334, 356Anemia, 181, 184Angiotensin-converting enzyme, 129, 131,197Angiotensin I, 197Angiotensin II, 129, 133, 197, 207, 225, 337Angiotensin receptor blockers, 228Angiotensin-converting enzyme inhibitors,228Angiotensinogen, 131, 225, 289Anion gap, 235-236Anterior commissure, 49, 52fAnterior corticospinal tract, 79Anterior pituitary glandanatomy of, 308, 311fhormones of, 316Antidiuretic hormonedescription of, 133-134plasma, 221release of, 221renal response to secretion of, 222fsecretion of, 312syndrome of inappropriate antidiuretichormone secretion, 217in thirst response, 248water channels affected by, 219, 221Antiporters, 13Antral cycle, 258Aortic aneurysm, 112Aortic arch, 131Aortic pressure, 110f, 115Aortic stenosis, 98Apical depolarization, 105fApneusis, 186Appetite, 248, 249fAquaporins, 15-16, 221Aqueduct of Sylvius, 50fArachidonic acid metabolites, 333Archicerebellum, 81Arterial baroreceptors, 131Arterial PCO2, 134377378IndexArterial pressuredescription of, 107monitoring of, 109regulation of, 131-134waveform for, 108fArteries, 125, 126fArteriolar tone, 128Arterioles, 125Arteriovenous oxygen gradient, 179-180Ascites, 284Asthma, 171, 334Atmospheric pressure, 163Atrial depolarization, 104fAtrial natriuretic peptide, 131, 207, 226, 337Atrial pressure, 115Atrioventricular block, 102Atrioventricular node, 98Atrioventricular node cells, 101Atropine, 91Auditory nerve, 68Auditory pathways, 69fAuditory system, 63, 66-69, 67fAuerbach’s plexus, 250Autonomic nervous systemactions of, 91tairway resistance affected by, 171cardiac output regulation by, 115-116components of, 87description of, 56divisions of, 87enteric nervous system regulated by, 254fheart rate regulation by, 117parasympathetic division of, 87, 88t,90f, 91tsympathetic division of, 87, 88t, 89f, 91tAutonomic receptors, 89, 91Axolemma, 34fAxondescription of, 30illustration of, 34fmyelinated, 31fAxon hillock, 28Axonal conduction, 31fBBainbridge reflex, 117, 131Bariatric surgery, 257Baroreceptor reflex, 116-117, 116f, 122Baroreceptorsdescription of, 12, 225low-pressure, 131pulse pressure effects on, 131Basal gangliaanatomy of, 49, 52motor system role of, 86Basement membrane, 199Basic electrical rhythm, 253Basket cells, 85Bicarbonatebuffering uses of, 231formation of, 298ions, 183losses of, 235renal handling of, 211, 232renal reabsorption of, 213fBicarbonate/chloride exchangers, 237Bile, 287, 289Bile acid, 283Bile canaliculi, 283Bile salt, 287Bile solids, 287Bilirubin, 285Bipolar cells, 62Bisynaptic reflex, 77, 81fBlood flowautoregulation of, 129cerebral, 134exercise-related changes, 137extrinsic regulation of, 129-130to kidneys, 198-199local regulation of, 129, 130fin lungs, 147-148pulmonary, 160frate of, 107regulation of, 127-130renal, 198-199velocity of, 111fBlood oxygen content, 179, 184fBlood pressuredescription of, 107-108long-term regulation of, 131, 133-134measurements of, 109monitoring of, 132fregulation of, 131-134response to changes in, 133fBlood-brain barrier, 49, 187“Blue bloater,” 188Body fluid compartments, 7fBone remodeling, 347Bony labyrinth, 66Borborygmi, 250Bowman’s capsule, 197, 202Boyle’s law, 156Brachial plexus, 55Bradycardia, 102Brainamygdala, 51anatomy of, 50fblood-brain barrier, 49cerebellum.
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