Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition 29. Human Development Text © The McGraw−Hill Companies, 2003 Chapter 29 Chapter 29 Human Development 1117 Fertilization and Preembryonic Development (p. 1090) 1. Sperm must travel to the distal one- third of the uterine tube if they are to encounter the egg before it dies. This traveling, or sperm migration, may be aided by the cervical mucus, female orgasm, and chemical attractants emitted by the egg. 2. Freshly ejaculated sperm cannot fertilize an egg. They undergo capacitation, becoming capable of fertilization, as they migrate. 3. When a sperm encounters an egg, it releases enzymes from its acrosome (the acrosomal reaction), enabling it to penetrate the cumulus oophorus, zone pellucida, and egg membrane. Hundreds of sperm may be needed to clear a path for the one that fertilizes the egg. 4. The egg has a fast block and a slow block to prevent fertilization by more than one sperm (polyspermy). The fast block employs a change in egg membrane voltage that inhibits the binding of additional sperm. The slow block involves exocytosis of the egg’s cortical granules to produce an impenetrable fertilization membrane around the egg. 5. The fertilized egg completes meiosis II and casts off a second polar body. The sperm and egg nuclei swell and form pronuclei. When the pronuclei rupture and their chromosomes mingle, the egg is a diploid zygote. 6. The first two weeks of development, called the preembryonic stage, consists of cleavage, implantation, and embryogenesis, resulting in an embryo. 7. Cleavage is the mitotic division of the zygote into cells called blastomeres. The stage that arrives at the uterus is a morula of about 16 blastomeres. It develops into a hollow ball called the blastocyst, with an outer cell mass called the trophoblast and inner cell mass called the embryoblast. 8. Implantation is the attachment of the blastocyst to the uterine wall. The trophoblast differentiates into a cellular mass called the cytotrophoblast next to the embryo, and a multinucleate mass called the syncytiotrophoblast, which grows rootlets into the endometrium. The endometrium grows over the blastocyst and soon completely covers it. 9. The trophoblast secretes human chorionic gonadotropin, the hormone that stimulates growth and secretion by the corpus luteum. 10. During implantation, the embryoblast differentiates into three primary germ layers—ectoderm, mesoderm, and endoderm. This process is embryogenesis. When the three primary germ layers have formed, 2 weeks after conception, the individual is an embryo. Embryonic and Fetal Development (p. 1094) 1. The next 6 weeks of development are marked by formation of the extra- embryonic membranes, placental nutrition, and appearance of the organ systems. 2. After implantation, the conceptus is fed by trophoblastic nutrition, in which the trophoblast digests decidual cells of the endometrium. This is the dominant mode of nutrition for 8 weeks. 3. The placenta begins to form 11 days after conception as chorionic villi of the trophoblast eat into uterine blood vessels, eventually creating a blood- filled cavity called the placental sinus. The chorionic villi grow into branched treelike structures surrounded by the maternal blood in the sinus. Nutrients diffuse from the maternal blood into embryonic blood vessels in the villi, and embryonic wastes diffuse the other way to be disposed of by the mother. Placental nutrition becomes dominant at 8 weeks and continues until birth. 4. The placenta communicates with the embryo and fetus by way of two arteries and a vein contained in the umbilical cord. 5. Four membranes are associated with the embryo and fetus: the amnion, yolk sac, allantois, and chorion. 6. The amnion is a translucent sac that encloses the embryo in a pool of amniotic fluid. This fluid protects the embryo from trauma and temperature fluctuations and allows freedom of movement and symmetric development. 7. The yolk sac contributes to development of the digestive tract and produces the first blood and germ cells of the embryo. 8. The allantois is an outgrowth of the yolk sac that forms a structural foundation for umbilical cord development and becomes part of the urinary bladder. 9. The chorion encloses all of the other membranes and forms the fetal part of the placenta. 10. Organogenesis is the differentiation of the primary germ layers into all of the organs and organ systems (table 29.2). Traces of all organ systems are present by the end of 8 weeks. The individual is considered a fetus from then until birth. 11. In the fetal stage, organs undergo growth and differentiation and become capable of functioning outside the mother’s body. Major developments in the fetal stage are summarized in table 29.4. 12. The circulatory system differs most markedly from prenatal to neonatal life. In the fetus, a pair of umbilical arteries arise from the internal iliac arteries and supply the placenta. A single umbilical vein returns from the placenta and drains most of its blood into the inferior vena cava (IVC). 13. Three bypasses or shunts divert fetal blood from organs that are not very functional before birth: The ductus venosus bypasses the liver and carries most umbilical vein blood directly to the IVC; the foramen ovale in the interatrial septum of the heart Chapter Review Review of Key Concepts Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition 29. Human Development Text © The McGraw−Hill Companies, 2003 Chapter 29 1118 Part Five Reproduction and Development allows blood to pass directly from the right atrium to the left atrium, bypassing the lungs; and the ductus arteriosus allows blood in the pulmonary trunk to pass directly into the aorta and bypass the lungs. The Neonate (p. 1101) 1. The first 6 to 8 hours after birth are a transitional period marked by increasing heart and respiratory rates and falling temperature. The first 6 weeks of postpartum life are the neonatal period. 2. After severance of the umbilical cord, the proximal parts of the umbilical arteries become vesical arteries, which supply the urinary bladder. Other blood vessels unique to the fetus close and become fibrous cords or ligaments. The foramen ovale and ductus arteriosus close so that blood from the right heart is forced to circulate through the lungs. 3. Breathing is very difficult for the neonate as it first inflates the pulmonary alveoli. 4. Neonatal immunity depends heavily on IgG acquired through the placenta and IgA from colostrum. By 6 months, the infant produces ample IgG of its own. 5. Neonatal thermoregulation is critical because infants lose heat easily. This heat loss is compensated for to some extent by a form of heat-producing adipose tissue called brown fat. 6. The neonatal kidneys are not very efficient at concentrating urine, so neonates have a relatively high rate of water loss and require more fluid intake than adults do relative to their body weight. 7. Premature infants suffer especially from respiratory distress syndrome, poor thermoregulation, poor fat digestion, and multiple dysfunctions resulting from inadequate liver function. 8. Congenital anomalies (birth defects) can result from infectious diseases, teratogens, mutagens, and genetic disorders. 9. Some of the more common and serious infectious diseases and pathogens of the newborn are herpes simplex, cytomegalovirus, HIV, gonorrhea, and syphilis. 10. Teratogens, agents that cause anatomical deformities, include alcohol, nicotine, and X rays. 11. Nondisjunction, the failure of homologous chromosomes to separate during meiosis, can result in such congenital defects as triplo-X, Klinefelter, Turner, and Down syndromes. Aging and Senescence (p. 1107) 1. Senescence is the degeneration that occurs in an organ system as we age. It begins at very different ages and progresses at different rates in different organ systems. Senescence of one organ system often contributes to the senescence of others. 2. Senescence of the integumentary system is marked by graying and thinning of the hair, atrophy of sebaceous glands, thinning and loss of elasticity in the skin, fragility of cutaneous blood vessels, decline in cutaneous sensory function, slower healing, and poorer thermoregulation. Intrinsic aging occurs inevitably with time, while photoaging is an added effect proportional to the amount of lifetime UV exposure. Senescence of the skin contributes to lactose intolerance, bone loss, muscle weakness, and poorer glandular secretion and synaptic transmission. 3. Senescence of the skeletal system is marked by loss of bone density (osteopenia or, when more severe, osteoporosis), increasing susceptibility to fractures, slower healing of fractures, osteoarthritis, and other degenerative joint diseases. 4. The aging muscular system exhibits muscular atrophy, loss of strength, and easy fatigue. Some loss of muscular function results from degenerative changes in the nervous system. 5. Senescence of the nervous system is marked by substantial loss of brain tissue and synapses, less efficient synaptic transmission, and declining motor coordination, intellectual function, and short-term memory, but relatively little loss of language skills and long-term memory. Senescence of the sympathetic division results in less effective homeostasis in other organ systems. 6. Visual acuity and auditory sensitivity begin to decline shortly after adolescence. Vision can be impaired by cataracts, glaucoma, and reduced dark adaptation. Declining inner-ear function can result in poor balance. Taste and smell become less sensitive. 7. The endocrine system shows relatively little senescence except for the decline in reproductive hormones. Reduced densities of hormone receptors can contribute to type II diabetes mellitus and poorer negative feedback control of the pituitary. 8. Senescence of the circulatory system is a leading cause of death. Anemia, atherosclerosis, thrombosis, varicose veins, hemorrhoids, and edema become more common in old age. Atherosclerosis contributes to weakening of the heart, myocardial infarction, aneurysm, stroke, and atrophy of all organs. 9. Senescence of the immune system makes older people more subject to cancer and infectious diseases. 10. Pulmonary functions decline as the thoracic cage becomes less flexible and the lungs have fewer alveoli. Pneumonia and chronic obstructive pulmonary diseases are major causes of death. 11. The kidneys atrophy a great deal with age, and thus elderly people are less able to maintain water balance and to clear drugs or toxins from the body. Elderly men are increasingly subject to prostatic enlargement and urine retention, and women to urinary incontinence. 12. Senescence of the digestive system includes reduced salivation, difficulty swallowing, poorer dental health, atrophy of the stomach, gastroesophageal reflux, constipation, loss of appetite, and impaired liver function. 13. Reproductive senescence is marked in men by reduced testosterone secretion, sperm count, and libido, and in women by menopause and multiple effects of the loss of estrogen secretion. 14. Exercise slows the rate of senescence and improves the quality of life in old age by maintaining strength, endurance, flexibility, and independence. It reduces the incidence and severity of hypertension, osteoporosis, obesity, and diabetes mellitus. 15. There are numerous theories of what causes senescence. Replicative senescence, a limit on how many times cells can divide, may stem from shortening of the chromosomal telomeres at each cell division. Cross- Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition 29. Human Development Text © The McGraw−Hill Companies, 2003 Chapter 29 Chapter 29 Human Development 1119 linking of proteins and DNA and the misfolding and other structural defects in proteins may cause increasing cellular dysfunction. The cumulative effects of free radical damage and increased incidence of autoimmune disease may be other factors in senescence. 16. Longevity is known to be partially hereditary. Natural selection has presumably been unable to eliminate genes that cause some of the diseases of old age because such genes have no effects that natural selection can act on until after the individual has reproduced. 17. Life expectancy has increased in modern times mostly because of our ability to reduce infant and childhood mortality. Life span, the maximum attainable age, has not markedly changed, however. 18. Death is usually clinically defined by an absence of brain waves, reflexes, or spontaneous respiration or heartbeat. Selected Vocabulary capacitation 1090 acrosomal reaction 1090 zygote 1091 morula 1091 blastocyst 1093 implantation 1093 embryo 1094 placenta 1095 amnion 1097 chorion 1098 fetus 1098 meconium 1101 lanugo 1101 vernix caseosa 1101 teratogen 1104 senescence 1107 telomere 1113 Testing Your Recall 1. When a conceptus arrives in the uterus, it is at what stage of development? a. zygote b. morula c. blastomere d. blastocyst e. embryo 2. The entry of a sperm nucleus into an egg must be preceded by a. the cortical reaction. b. the acrosomal reaction. c. the fast block. d. implantation. e. cleavage. 3. The stage of the conceptus that implants in the uterine wall is a. a blastomere. b. a morula. c. a blastocyst. d. an embryo. e. a zygote. 4. Chorionic villi develop from a. the zona pellucida. b. the endometrium. c. the syncytiotrophoblast. d. the embryoblast. e. the corona radiata. 5. Which of these results from aneuploidy? a. Turner syndrome b. fetal alcohol syndrome c. nondisjunction d. progeria e. rubella 6. Fetal urine accumulates in the _______ and contributes to the fluid there. a. placental sinus b. yolk sac c. allantois d. chorion e. amnion 7. One theory of senescence is that it results from a lifetime of damage by a. teratogens. b. aneuploidy. c. free radicals. d. cytomegalovirus. e. nondisjunction. 8. Photoaging is a major factor in the senescence of a. the integumentary system. b. the eyes. c. the nervous system. d. the skeletal system. e. the cardiovascular system. 9. Which of these is not a common effect of senescence? a. reduced synthesis of vitamin D b. atrophy of the kidneys c. atrophy of the cerebral gyri d. increased herniation of intervertebral discs e. reduced pulmonary vital capacity 10. For the first 8 weeks of gestation, a conceptus is nourished mainly by a. the placenta. b. amniotic fluid. c. colostrum. d. decidual cells. e. yolk cytoplasm. 11. Viruses and chemicals that cause congenital anatomical deformities are called _______. 12. Aneuploidy is caused by _______, the failure of two homologous chromosomes to separate in meiosis. 13. The maximum age attainable by a member of the human species is called the _______. 14. The average age attained by humans in a given population is called the _______. 15. Fetal blood flows through growths called _______, which project into the placental sinus. 16. The enzymes with which a sperm penetrates an egg are contained in an organelle called the _______. 17. Stiffening of the arteries, joints, and lenses in old age may be a result of cross-linking between _______ molecules. Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition 29. Human Development Text © The McGraw−Hill Companies, 2003 Chapter 29 1120 Part Five Reproduction and Development 18. An enlarged tongue, epicanthal folds of the eyes, and mental retardation are characteristic of a genetic anomaly called _______. 19. The fossa ovalis is a remnant of a fetal shunt called the _______. 20. A developing individual is first classified as a/an _______ when the three primary germ layers have formed. Answers in Appendix B Answers in Appendix B True or False Determine which five of the following statements are false, and briefly explain why. 1. Freshly ejaculated sperm are more capable of fertilizing an egg than are sperm several hours old. 2. Fertilization normally occurs in the lumen of the uterus. 3. An egg is usually fertilized by the first sperm that contacts it. 4. By the time a conceptus reaches the uterus, it has already undergone several cell divisions and consists of 16 cells or more. 5. The conceptus is first considered a fetus when all of the organ systems are present. 6. The placenta becomes increasingly permeable as it develops. 7. The endocrine system shows less senescence in old age than most other organ systems. 8. Fetal blood bypasses the nonfunctional liver by passing through the foramen ovale. 9. Blood in the umbilical vein has a higher P O 2 than blood in the umbilical arteries. 10. It is well established that people who exercise regularly live longer than those who do not. Testing Your Comprehension 1. Suppose a woman had a mutation resulting in a tough zona pellucida that did not disintegrate after the egg was fertilized. How would this affect her fertility? Why? 2. Suppose a drug were developed that could slow down the rate of collagen cross-linking with age. What diseases of old age could be made less severe with such a drug? 3. Some health-food stores market the enzyme superoxide dismutase (SOD) as an oral antioxidant to retard senescence. Explain why it would be a waste of your money to buy it. 4. In some children, the ductus arteriosus fails to close after birth—a condition that eventually requires surgery. Predict how this condition would affect (a) pulmonary blood pressure, (b) systemic diastolic pressure, and (c) the right ventricle of the heart. 5. Only one sperm is needed to fertilize an egg, yet a man who ejaculates fewer than 10 million sperm is usually infertile. Explain this apparent contradiction. Supposing 10 million sperm were ejaculated, predict how many would come within close range of the egg. How likely is it that any one of these sperm would fertilize it? Answers at the Online Learning Center Answers to Figure Legend Questions 29.2 An unfertilized egg dies long before it reaches the uterus. 29.7 Eight weeks 29.12 Subcutaneous fat deposition occurs largely in the eighth month. 29.14 XXY (Klinefelter syndrome) and YO (a zygote that would not survive) 29.16 Female, as seen from the two X chromosomes at the lower right www.mhhe.com/saladin3 The Online Learning Center provides a wealth of information fully organized and integrated by chapter. You will find practice quizzes, interac- tive activities, labeling exercises, flashcards, and much more that will complement your learning and understanding of anatomy and physiology. Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Appendix A Periodic Table of Elements © The McGraw−Hill Companies, 2003 Nineteenth-century chemists discovered that when they arranged the known elements by atomic weight, certain properties reappeared periodically. In 1869, Russian chemist Dmitri Mendeleev published the first modern periodic table of the elements, leaving gaps for those that had not yet been discovered. He accurately predicted properties of the missing elements, which helped other chemists discover and isolate them. Each row in the table is a period and each column is a group (family). Each period has one electron shell more than the period above it, and as we progress from left to right within a period, each element has one more proton and electron than the one before. The dark steplike line from boron (5) to astatine (85) separates the metals to the left of it (except hydrogen) from the nonmetals to the right. Each period begins with a soft, light, highly reactive alkali metal, with one valence electron, in family IA. Progressing from left to right, the metallic properties of the elements become less and less pronounced. Elements in family VIIA are highly reactive gases called halogens, with seven valence electrons. Elements in family VIIIA, called noble (inert) gases, have a full valence shell of eight electrons, which makes them chemically unreactive. Ninety-one of the ele- ments occur naturally on earth. Physicists have created ele- ments up to atomic number 118 in the laboratory, but the International Union of Pure and Applied Chemistry has established formal names only through element 109 to date. The 24 elements with normal roles in human physi- ology are color-coded according to their relative abun- dance in the body (see chapter 2). Others, however, may be present as contaminants with very destructive effects (such as arsenic, lead, and radiation poisoning). Appendix A Periodic Table of the Elements A-1 1 Hydrogen H 1.0079 IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA VIIIA 1 57–71, Lanthanides Transition metals 89 –103, Actinides 2 3 4 Period 5 6 7 3 Lithium Li 6.941 11 Sodium Na 22.989 37 Rubidium Rb 85.468 55 Cesium Cs 132.905 87 Francium Fr (223) 4 Beryllium Be 9.0122 12 Magnesium Mg 24.305 20 Calcium Ca 40.08 38 Strontium Sr 87.62 56 Barium Ba 137.34 88 Radium Ra (226) 21 Scandium Sc 44.956 39 Yitrium Y 88.905 22 Titanium Ti 47.90 40 Zirconium Zr 91.22 72 Hafnium Hf 178.49 104 Rutherfordium Rf (261) 23 Vanadium V 50.942 41 Niobium Nb 92.906 73 Tantalum Ta 180.948 105 Hahnium Ha (262) 24 Chromium Cr 51.996 42 Molybdenum Mo 95.94 74 Tungsten W 183.85 106 Seaborgium Sg (263) 25 Manganese Mn 54.938 43 Technetium Tc (99) 75 Rhenium Re 186.2 107 Neilsbohrium Ns (261) 26 Iron Fe 55.847 44 Ruthenium Ru 101.07 76 Osmium Os 190.2 108 Hassium Hs (265) 27 Cobalt Co 58.933 45 Rhodium Rh 102.905 77 Iridium Ir 192.2 109 Meitnerium Mt (266) 28 Nickel Ni 58.71 46 Palladium Pd 106.4 78 Platinum Pt 195.09 29 Copper Cu 63.546 47 Silver Ag 107.868 79 Gold Au 196.967 30 Zinc Zn 65.38 48 Cadmium Cd 112.40 80 Mercury Hg 200.59 5 Boron B 10.811 13 Aluminum Al 26.9815 31 Gallium Ga 69.723 49 Indium In 114.82 81 Thallium Ti 204.37 6 Carbon C 12.0112 14 Silicon Si 28.086 32 Germanium Ge 72.59 50 Tin Sn 118.69 82 Lead Pb 207.19 7 Nitrogen N 14.0067 15 Phosphorus P 30.9738 33 Arsenic As 74.992 51 Antimony Sb 121.75 83 Bismuth Bi 208.980 60 Neodymium Nd 144.24 59 Praseodymium Pr 140.907 58 Cerium Ce 140.12 57 Lanthanum La 138.91 61 Promethium Pm 144.913 62 Samarium Sm 150.35 63 Europium Eu 151.96 64 Gadolinium Gd 157.25 65 Terbium Tb 158.925 66 Dysprosium Dy 162.50 67 Holmium Ho 164.930 68 Erbium Er 167.26 69 Thulium Tm 168.934 70 Ytterbium Yb 173.04 71 Lutetium Lu 174.97 8 Oxygen O 15.9994 16 Sulfur S 32.064 34 Selenium Se 78.96 52 Tellurium Te 127.60 84 Polonium Po (209) 9 Fluorine F 18.9984 17 Chlorine Cl 35.453 35 Bromine Br 79.904 53 Iodine I 126.904 85 Astatine At (210) 2 Helium He 4.0026 10 Neon Ne 20.179 18 Argon Ar 39.948 36 Krypton Kr 83.80 54 Xenon Xe 131.30 86 Radon Rn (222) 92 Uranium U 238.03 91 Protactinium Pa (231) 90 Thorium Th 232.038 89 Actinium Ac (227) 93 Neptunium Np (237) 94 Plutonium Pu 244.064 95 Americium Am (243) 96 Curium Cm (247) 97 Berkelium Bk (247) 98 Californium Cf 242.058 99 Einsteinium Es (254) 100 Fermium Fm 257.095 101 Mendelevium Md 258.10 102 Nobelium No 259.10 103 Lawrencium Lr 260.105 1 Hydrogen H 1.0079 Key 98.5% (6 elements) Percent of human body (by weight) Atomic number Name Symbol Atomic mass 0.8% (6 elements) 0.7% (12 trace elements) 19 Potassium K 39.098 Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Appendix B Answers to Chapter Review Questions © The McGraw−Hill Companies, 2003 Appendix B Answers to Chapter Review Questions A-2 This appendix provides answers to the end-of-chapter Testing Your Recall and True/False questions. In the True or False sec- tions, all statements are true except those listed and explained here. Answers to the figure legend questions are given at the end of each chapter; answers to Think About It and Testing Your Comprehension questions are in the Instructor’s Manual; and answers to Testing Your Comprehension are also given at the Online Learning Center at www.mhhe.com/saladin3. Chapter 1 1. a 8. c 15. homeostasis 2. e 9. d 16. set point 3. d 10. b 17. negative feedback 4. a 11. dissection 18. organ 5. c 12. Hooke 19. stereoscopic 6. c 13. deduction 20. prehensile, 7. a 14. psychosomatic opposable True or False (explanation of the false statements only) 3. Auscultation means listening to body sounds, not inspecting its appearance. 6. Leeuwenhoek was a textile merchant who built microscopes to examine fabric. 7. A scientific theory is founded on a large body of evidence, summarizing what is already known. 8. Both the treatment and control groups consist of volunteer patients. 10. Negative feedback is a self-corrective process with a beneficial effect on the body. Atlas A 1. d 8. d 15. hand, foot 2. c 9. b 16. meninges 3. e 10. d 17. retroperitoneal 4. d 11. supine 18. medial 5. d 12. parietal 19. inferior 6. a 13. mediastinum 20. cubital, popliteal 7. a 14. nuchal True or False (explanation of the false statements only) 4. The diaphragm is inferior to the lungs. 5. The esophagus is in the ventral body cavity. 6. The liver is in the hypochondriac region, superior to the lateral abdominal region. 9. The peritoneum lines the outside of the stomach and intestines. 10. The sigmoid colon is in the lower left quadrant. Chapter 2 1. a 8. c 14. anabolism 2. c 9. b 15. dehydration 3. a 10. d synthesis 4. c 11. cation 16. -ose, -ase 5. a 12. free radicals 17. phospholipids 6. e 13. catalyst, 18. cyclic adenosine 7. b enzymes monophosphate 19. anaerobic 20. substrate fermentation True or False (explanation of the false statements only) 1. The monomers of a polysaccharide are monosaccharides (simple sugars). 3. Such molecules are called isomers, not isotopes. 6. A saturated fat is one to which no more hydrogen can be added. 8. Above a certain temperature, enzymes denature and cease working. 9. These solutes have different molecular weights, so 2% solutions would not contain the same amount of solute. Chapter 3 1. e 9. d 16. exocytosis 2. b 10. b 17. nucleus, 3. d 11. micrometers mitochondria 4. b 12. second messenger 18. smooth ER, 5. e 13. voltage-regulated peroxisomes 6. e 14. hydrostatic 19. ligand-regulated 7. a pressure gate 8. c 15. hypertonic 20. cisterna True or False (explanation of the false statements only) 1. Osmosis does not require ATP. 3. Second messengers activate enzymes in the cell; they are not transport proteins. 5. A channel could not move material from the outside of a cell to the inside unless it extended all the way across the membrane; it must be an integral protein. 6. The plasma membrane consists primarily of phospholipid molecules. 7. The brush border is composed of microvilli. Chapter 4 1. a 8. d 15. RNA polymerased 2. e 9. d 16. chaperones 3. c 10. a 17. 46, 92, 92 4. c 11. cytokinesis 18. ribosome 5. e 12. alleles 19. growth factors 6. b 13. genetic code 20. autosomes 7. a 14. polyribosome True or False (explanation of the false statements only) 1. There are no ribosomes on the Golgi complex; they are on the rough ER. 2. There are no genes for steroids, carbohydrates, or phospholipids, but only for proteins. 6. This law describes the pairing of bases between the two strands of DNA, not between mRNA and tRNA. 9. Males have only one X chromosome, but have two sex chromosomes (the X and Y). 10. Several RNA polymerase molecules at once can transcribe a gene. Chapter 5 1. a 3. c 5. c 2. b 4. e 6. a Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Appendix B Answers to Chapter Review Questions © The McGraw−Hill Companies, 2003 Appendix B Answers to Chapter Review Questions A-3 7. b 13. lacunae 18. matrix 8. e 14. fibers (extracellular 9. b 15. collagen material) 10. b 16. skeletal muscle 19. proteoglycans 11. necrosis 17. basement 20. simple 12. mesothelium membrane True or False (explanation of the false statements only) 1. The esophageal epithelium is nonkeratinized. 5. Adipose tissue is an exception; cells constitute most of its volume. 6. Adipocytes are also found in areolar tissue, either singly or in small clusters. 7. Tight junctions serve mainly to restrict the passage of material between cells. 10. Perichondrium is lacking from fibrocartilage and from hyaline articular cartilage. Chapter 6 1. d 9. a 16. earwax 2. c 10. d 17. sebaceous 3. d 11. insensible glands 4. b perspiration 18. anagen 5. a 12. piloerector 19. dermal 6. e 13. debridement papilla 7. c 14. cyanosis 20. third-degree 8. a 15. dermal papillae True or False (explanation of the false statements only) 3. Keratin is the protein of the epidermis; the dermis is composed mainly of collagen. 4. Vitamin D synthesis begins in the keratinocytes. 7. The hypodermis is not considered to be a layer of the skin. 8. Different races have about the same density of melanocytes but different amounts of melanin. 9. A genetic lack of melanin causes albinism, not pallor. Pallor is a temporary, nonhereditary paleness of the skin. Chapter 7 1. e 8. e 15. hypocalcemia 2. a 9. b 16. osteoblasts 3. d 10. d 17. calcitriol 4. c 11. hydroxyapatite 18. osteoporosis 5. d 12. canaliculi 19. metaphysis 6. a 13. appositional 20. osteomalacia 7. d 14. solubility product True or False (explanation of the false statements only) 3. The most common bone disease is osteoporosis, not fractures. 4. Bones elongate at the epiphyseal plate, not the articular cartilage. 5. Osteoclasts develop from stem cells in the bone marrow, not from osteoblasts. 7. Hydroxyapatite is the major mineral of bone; the major protein is collagen. 9. The major effect of vitamin D is bone resorption, though it also promotes deposition. Chapter 8 1. b 9. e 17. auricular 2. e 10. b 18. styloid 3. a 11. fontanels 19. pollex, 4. d 12. temporal hallux 5. a 13. sutures 20. medial 6. e 14. sphenoid longitudinal 7. c 15. annulus fibrosus 8. b 16. dens True or False (explanation of the false statements only) 2. Each hand and foot has 14 phalanges. 3. The female pelvis is wider and shallower than the male’s. 7. The lumbar vertebrae have transverse processes but no transverse costal facets. 8. The most frequently broken bone is the clavicle. 9. Arm refers to the region containing only the humerus; leg refers to the region containing the tibia and fibula. Chapter 9 1. c 8. d 15. gomphosis 2. b 9. b 16. serrate 3. a 10. d 17. extension 4. e 11. synovial fluid 18. range of motion 5. c 12. bursa 19. labrum 6. c 13. pivot 20. menisci 7. a 14. kinesiology True or False (explanation of the false statements only) 1. Osteoarthritis occurs in almost everyone after a certain age; rheumatoid arthritis is less common. 2. A kinesiologist studies joint movements; a rheumatologist treats arthritis. 3. Synovial joints are diarthroses and amphiarthroses but never synarthroses. 7. The round ligament is somewhat slack and probably does not secure the femoral head. 9. Synovial fluid is secreted by the synovial membrane of the joint capsule and fills the bursae. Chapter 10 1. b 8. a 14. hamstring 2. e 9. d 15. flexor retinacula 3. a 10. c 16. urogenital triangle 4. c 11. origin 17. linea alba 5. e 12. fascicle 18. synergist 6. e 13. prime mover 19. bipennate 7. b (agonist) 20. sphincter True or False (explanation of the false statements only) 3. The mastoid process is its insertion. 7. The trapezius is superficial to the scalenes. 8. Normal exhalation does not employ these muscles. 9. They result from rapid extension of the knee, not flexion. 10. They are on opposite sides of the tibia and act as antagonists. Atlas B 1. f 11. y 21. k 2. b 12. m 22. d 3. k 13. n 23. f 4. p 14. e 24. b 5. h 15. g 25. a 6. z 16. v 26. u 7. o 17. f 27. j 8. x 18. c 28. i 9. c 19. y 29. g 10. a 20. x 30. q Chapter 11 1. a 8. c 15. acetylcholine 2. d 9. e 16. myoglobin 3. b 10. b 17. Z discs 4. d 11. threshold 18. varicosities 5. a 12. complete tetanus 19. muscle tone 6. c 13. terminal cisternae 20. lactic acid 7. e 14. myosin True or False (explanation of the false statements only) 1. A motor neuron may supply 1,000 or more muscle fibers; a motor unit consists of one motor neuron and all the muscle fibers it innervates. 2. Calcium binds to troponin, not to myosin. Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Appendix B Answers to Chapter Review Questions © The McGraw−Hill Companies, 2003 6. Thick and thin filaments are present but not arranged in a way that produces striations. 7. Under natural conditions, a muscle seldom or never attains complete tetanus. 9. A muscle produces most of its ATP during this time by anaerobic fermentation, which generates lactic acid; it does not consume lactic acid. Chapter 12 1. e 9. d 15. oligodendrocytes 2. c 10. b 16. nodes of Ranvier 3. d 11. afferent 17. axon hillock, 4. a 12. conductivity initial segment 5. c 13. absolute 18. norepinephrine 6. e refractory period 19. facilitated zone 7. d 14. dendrites 20. neuromodulators 8. a True or False (explanation of the false statements only) 4. The Na ϩ outflow depolarizes the neuron and the K ϩ inflow repolarizes it. 5. The threshold stays the same but an EPSP brings the membrane potential closer to the threshold. 7. The effect of a neurotransmitter varies from place to place depending on the type of receptor present. 8. The signals travel rapidly through the internodes and slow down at each node of Ranvier. 9. Synaptic contacts are remodeled, added, and removed throughout life. Chapter 13 1. e 8. a 15. intrafusal fibers 2. c 9. e 16. phrenic 3. d 10. b 17. decussation 4. d 11. ganglia 18. proprioception 5. e 12. ramus 19. dorsal root 6. c 13. spinocerebellar 20. tibial, common 7. c 14. crossed extensor fibular True or False (explanation of the false statements only) 1. The gracile fasciculus is an ascending (sensory) tract. 4. All spinal nerves are mixed nerves; none are purely sensory or motor. 5. The dura is separated from the bone by a fat-filled epidural space. 8. Dermatomes overlap each other by as much as 50%. 9. Some somatic reflexes are mediated primarily through the brainstem and cerebellum. Chapter 14 1. c 8. d 14. hydrocephalus 2. a 9. e 15. choroid plexus 3. e 10. e 16. precentral 4. a 11. corpus callosum 17. frontal 5. b 12. ventricles, 18. association areas 6. c cerebrospinal 19. categorical 7. a 13. arbor vitae 20. Broca’s area True or False (explanation of the false statements only) 1. This fissure separates the cerebral hemispheres, not the cerebellar hemispheres. 2. The cerebral hemispheres do not develop from neural crest tissue. 5. The choroid plexuses produce only 30% of the CSF. 6. Hearing is a temporal lobe function; vision resides in the occipital lobe. 10. Eye movements are controlled by the oculomotor, trochlear, and abducens nerves; the optic nerve serves only to carry visual information. Chapter 15 1. b 8. d 15. enteric 2. c 9. a 16. norepinephrine 3. e 10. c 17. sympathetic 4. e 11. adrenergic 18. preganglionic, 5. a 12. dual innervation postganglionic 6. e 13. autonomic tone 19. cAMP 7. d 14. vagus 20. vasomotor tone True or False (explanation of the false statements only) 1. Both systems are always simultaneously active. 3. In biofeedback and other circumstances, limited voluntary control of the ANS is possible. 4. The sympathetic division inhibits digestion. 6. Waste elimination can occur by autonomic spinal reflexes without necessarily involving the brain. 7. All parasympathetic fibers are cholinergic. Chapter 16 1. a 8. c 15. hair cells 2. c 9. c 16. stapes 3. b 10. b 17. inferior colliculi 4. a 11. fovea centralis 18. taste hairs 5. e 12. ganglion 19. olfactory bulb 6. e 13. Na ϩ 20. referred pain 7. d 14. otoliths True or False (explanation of the false statements only) 1. These fibers end in the medulla oblongata. 3. Because of hemidecussation, the right hemisphere receives signals from both eyes. 5. The posterior chamber, the space between iris and lens, is filled with aqueous humor. 6. Descending analgesic fibers block signals that have reached the dorsal horn of the spinal cord. 10. The trochlear and abducens nerves control the superior oblique and lateral rectus, respectively. Chapter 17 1. b 10. e 17. negative 2. d 11. adenohypophysis feedback 3. a 12. tyrosine inhibition 4. c 13. acromegaly 18. hypophyseal 5. c 14. cortisol portal system 6. c 15. glucocorticoids 19. permissive 7. d 16. granulosa, 20. up-regulation 8. c interstitial 9. e True or False (explanation of the false statements only) 5. Hormones are also secreted by the heart, liver, kidneys, and other organs not generally regarded as glands. 7. The pineal gland and thymus undergo involution with age. 8. Without iodine, there is no thyroid hormone (TH); without TH, there can be no negative feedback inhibition. 9. The tissue at the center is the adrenal medulla. 10. There are also two testes, two ovaries, and four parathyroid glands. Chapter 18 1. b 6. d 11. hemopoiesis 2. c 7. d 12. hematocrit, or 3. c 8. c packed cell volume 4. a 9. d 13. thromboplastin 5. b 10. c 14. agglutinogens A-4 Appendix B Answers to Chapter Review Questions Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Appendix B Answers to Chapter Review Questions © The McGraw−Hill Companies, 2003 Appendix B Answers to Chapter Review Questions A-5 15. hemophilia 18. polycythemia 20. erythropoietin 16. hemostasis 19. vitamin B 12 17. sickle-cell disease True or False (explanation of the false statements only) 3. Oxygen deficiency is the result of anemia, not its cause. 4. Clotting is one mechanism of hemostasis, but hemostasis includes others. Agglutination is unrelated to either of these. 6. The most abundant WBCs are neutrophils. 9. The heme is excreted; the globin is broken down into amino acids that can be reused. 10. In leukemia, there is an excess of WBCs. A WBC deficiency is leukopenia. Chapter 19 1. d 8. e 14. Na ϩ 2. b 9. a 15. gap junctions 3. d 10. e 16. T wave 4. a 11. systole, diastole 17. semilunar 5. e 12. systemic 18. auscultation 6. c 13. atrioventricular 19. preload 7. d (coronary) sulcus 20. cardiac output True or False (explanation of the false statements only) 1. The coronary circulation is part of the systemic circuit; the other division is the pulmonary circuit. 3. The first two-thirds of ventricular filling occurs before the atria contract. The atria add only about 31% of the blood that fills the ventricles. 6. The first heart sound occurs at the time of the QRS complex. 7. The heart has its own internal pacemaker and would continue beating; the nerves only alter the heart rate. 10. The ECG is a composite record of the electrical activity of the entire myocardium, not a record from a single myocyte. It looks much different from an action potential. Chapter 20 1. c 8. a 14. thoracic pump 2. b 9. e 15. oncotic pressure 3. a 10. d 16. transcytosis 4. e 11. systolic, diastolic 17. sympathetic 5. b 12. continuous 18. baroreceptors 6. c capillaries 19. the arterial circle 7. e 13. anaphylactic 20. basilic, cephalic True or False (explanation of the false statements only) 4. Some veins have valves, but arteries do not. 5. By the formula F ϰ r 4 , the flow increases 16-fold. 8. The capillaries normally reabsorb about 85% of the fluid they filter; the rest is absorbed by the lymphatic system. 9. An aneurysm is a weak, bulging vessel which may rupture. 10. Anaphylactic shock is a form of venous pooling shock. Chapter 21 1. b 9. a 15. opsonization 2. c 10. c 16. pyrogen 3. a 11. pathogen 17. interleukins 4. a 12. lysozyme 18. antigen-binding 5. d 13. lymphadenitis site, epitope 6. b 14. diapedesis 19. clonal deletion 7. e (emigration) 20. autoimmune 8. d True or False (explanation of the false statements only) 1. Lysozyme is a bacteria-killing enzyme. 3. Interferons promote inflammation. 4. Helper T cells are also necessary to humoral immunity. 9. Anergy is a loss of lymphocyte activity, whereas autoimmune diseases result from misdirected activity. 10. Interferons inhibit viral replication; perforins lyse bacteria. Chapter 22 1. c 10. a 17. compliance, 2. c 11. glottis elasticity 3. a 12. bronchial tree 18. inspiratory 4. e 13. pulmonary surfactant center 5. e 14. intrapleural, 19. ventilation- 6. c atmospheric perfusion 7. b 15. obstructive coupling 8. a 16. anatomic dead 20. alkalosis, 9. d space hypocapnia True or False (explanation of the false statements only) 1. The glottis is the superior opening into the larynx, not its inferior exit. 4. When volume increases, pressure decreases. 5. Atelectasis can have other causes such as airway obstruction. 8. In an average 500 mL tidal volume, 350 mL reaches the alveoli. 10. Most CO 2 is transported as bicarbonate ion. Chapter 23 1. a 9. c 16. transport 2. d 10. a maximum 3. b 11. micturition 17. antidiuretic 4. c 12. renal autoregulation hormone 5. b 13. trigone 18. internal urethral 6. b 14. macula densa 19. protein 7. d 15. podocytes 20. arcuate 8. e True or False (explanation of the false statements only) 1. Parathyroid hormone regulates calcium absorption by the PCT. 2. Urine contains more urea and chloride than sodium. 4. A substantial amount of tubular fluid is reabsorbed by the paracellular route, passing through leaky tight junctions. 5. Glycosuria does not occur in diabetes insipidus. 8. Urine can be as dilute as 50 mOsm/L. Chapter 24 1. c 9. d 16. hyperkalemia 2. a 10. b 17. hyponatremia 3. a 11. Na ϩ 18. respiratory 4. a 12. K ϩ acidosis 5. d 13. metabolic water 19. limiting pH 6. c 14. cutaneous 20. osmolarity 7. e transpiration 8. b 15. fluid sequestration True or False (explanation of the false statements only) 2. Aldosterone has only a small influence on blood pressure. 5. PTH promotes calcium absorption but phosphate excretion. 6. Protein buffers more acid than bicarbonate or phosphates do. 9. More water than salt is lost, so the body fluids become hypertonic. 10. Aquaporins are found in the distal tubule and collecting duct. Chapter 25 1. b 4. e 7. a 2. d 5. a 8. a 3. c 6. c 9. a [...]... erection of the hair; also called arrector pili fig 6.8 pineal gland (PIN-ee-ul) A small conical endocrine gland arising from the roof of the third ventricle of the brain; produces melatonin and serotonin and may be involved in timing the onset of puberty fig 14. 12 Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition G-15 End Matter Glossary © The McGraw−Hill Companies, 20 03 Glossary... Inc.; 21 .30: Photo Researchers, Inc Chapter 22 Chapter Opener 22 : Peter Arnold; 22 .2a,b: © The McGraw-Hill Companies, Inc / Joe DeGrandis, photographer; 22 .3a: © The McGraw-Hill Companies, Inc / Rebecca Gray, photographer / Don Kincaid, dissections; 22 .5: Phototake; 22 .8: Custom Medical Stock; 22 .9b: © The McGraw-Hill Companies, Inc / Karl Rubin, photographer; 22 .10: © Imagingbody; 22 .11a: Phototake; 22 .11b:... Between the ribs, as in the intercostal muscles, arteries, veins, and nerves interdigitate (IN-tur-DIDJ-ih-tate) To fit together like the fingers of two folded hands; for example, at the dermal-epidermal boundary, intercalated discs of the heart, and pedicels of the podocytes in the kidney fig 23 .9 Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition G-11 End Matter Glossary © The. .. Unlimited; 21 .11, 21 .12a,b: © The McGraw-Hill Companies, Inc / Dennis Strete, photographer; 21 .18b: Peter Arnold Inc.; 21 .19: From: Tissues and Organs: A TextAtlas of Scanning Electron Microscopy, © Richard G Kessel and Randy H Kardon, published by W.H Freeman and Company 1 979 .; 21 .22 a,b: Dr Andrejs Liepins; 21 .24 a,b: Visuals Unlimited; 21 .25 b: Peter Arnold, Inc.; 21 .28 : Visuals Unlimited; 21 .29 b: © NIBSC... organ system specialized for the intake of air and exchange of gases with the blood, consisting of the lungs and the air passages from the nose to the bronchi Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Glossary © The McGraw−Hill Companies, 20 03 Glossary resting membrane potential (RMP) A stable voltage across the plasma membrane of an unstimulated cell reticular... extension of an organ such as the penis and clitoris figs 27 .7, 28 .8 cuboidal (cue-BOY-dul) A cellular shape that is roughly like a cube or in which the height and width are about equal cuneiform (cue-NEE-ih -form) Wedge-shaped, as in the cuneiform cartilages of the larynx and cuneiform bone of the wrist current A moving stream of charged particles such as ions or electrons cusp 1 One of the flaps of a valve... 7. 11 epiphysis (eh-PIF-ih-sis) 1 The head of a long bone 2 The pineal gland (epiphysis cerebri) epithelium A type of tissue consisting of one or more layers of closely adhering cells with little intercellular material and no blood vessels; forms the coverings and linings of many organs and the parenchyma of the glands erectile tissue A tissue that functions by swelling with blood, as in the penis and. .. levels of the CNS to the cerebrum fig 14. 12 theory An explanatory statement, or set of statements, that concisely summarizes the state of knowledge on a phenomenon and provides direction for further study; for example, the fluid mosaic theory of the plasma membrane and the sliding filament theory of muscle contraction thermogenesis The production of heat, for example, by shivering or by the action of thyroid... adenine in the double helix of DNA fig 4 .2 thymus A lymphatic organ in the mediastinum superior to the heart; the site where T lympho- Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition End Matter Glossary © The McGraw−Hill Companies, 20 03 Glossary cytes differentiate and become immunocompetent fig 21 .10 thyroid gland An endocrine gland in the neck, partially encircling the trachea... period in the lives of men and women, usually in the early 50s, marked by changes in the level of reproductive hormones, a variety of somatic and psychological effects, and in women, cessation of ovulation and menstruation (menopause) Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition G-5 End Matter Glossary © The McGraw−Hill Companies, 20 03 Glossary clone A population of cells . Actinides 2 3 4 Period 5 6 7 3 Lithium Li 6.941 11 Sodium Na 22 .989 37 Rubidium Rb 85.468 55 Cesium Cs 1 32. 905 87 Francium Fr (22 3) 4 Beryllium Be 9.0 122 12 Magnesium Mg 24 .305 20 Calcium Ca 40.08 38 Strontium Sr 87. 62 56 Barium Ba 1 37. 34 88 Radium Ra (22 6) 21 Scandium Sc 44.956 39 Yitrium Y 88.905 22 Titanium Ti 47. 90 40 Zirconium Zr 91 .22 72 Hafnium Hf 178 .49 104 Rutherfordium Rf (26 1) 23 Vanadium V 50.9 42 41 Niobium Nb 92. 906 73 Tantalum Ta 180.948 105 Hahnium Ha (26 2) 24 Chromium Cr 51.996 42 Molybdenum Mo 95.94 74 Tungsten W 183.85 106 Seaborgium Sg (26 3) 25 Manganese Mn 54.938 43 Technetium Tc (99) 75 Rhenium Re 186 .2 1 07 Neilsbohrium Ns (26 1) 26 Iron Fe 55.8 47 44 Ruthenium Ru 101. 07 76 Osmium Os 190 .2 108 Hassium Hs (26 5) 27 Cobalt Co 58.933 45 Rhodium Rh 1 02. 905 77 Iridium Ir 1 92. 2 109 Meitnerium Mt (26 6) 28 Nickel Ni 58 .71 46 Palladium Pd 106.4 78 Platinum Pt 195.09 29 Copper Cu 63.546 47 Silver Ag 1 07. 868 79 Gold Au 196.9 67 30 Zinc Zn 65.38 48 Cadmium Cd 1 12. 40 80 Mercury Hg 20 0.59 5 Boron B 10.811 13 Aluminum Al 26 .9815 31 Gallium Ga 69. 72 3 49 Indium In 114. 82 81 Thallium Ti 20 4. 37 6 Carbon C 12. 01 12 14 Silicon Si 28 .086 32 Germanium Ge 72 . 59 50 Tin Sn 118.69 82 Lead Pb 20 7. 19 7 Nitrogen N 14.00 67 15 Phosphorus P 30. 973 8 33 Arsenic As 74 .9 92 51 Antimony Sb 121 .75 83 Bismuth Bi 20 8.980 60 Neodymium Nd 144 .24 59 Praseodymium Pr 140.9 07 58 Cerium Ce 140. 12 . Actinides 2 3 4 Period 5 6 7 3 Lithium Li 6.941 11 Sodium Na 22 .989 37 Rubidium Rb 85.468 55 Cesium Cs 1 32. 905 87 Francium Fr (22 3) 4 Beryllium Be 9.0 122 12 Magnesium Mg 24 .305 20 Calcium Ca 40.08 38 Strontium Sr 87. 62 56 Barium Ba 1 37. 34 88 Radium Ra (22 6) 21 Scandium Sc 44.956 39 Yitrium Y 88.905 22 Titanium Ti 47. 90 40 Zirconium Zr 91 .22 72 Hafnium Hf 178 .49 104 Rutherfordium Rf (26 1) 23 Vanadium V 50.9 42 41 Niobium Nb 92. 906 73 Tantalum Ta 180.948 105 Hahnium Ha (26 2) 24 Chromium Cr 51.996 42 Molybdenum Mo 95.94 74 Tungsten W 183.85 106 Seaborgium Sg (26 3) 25 Manganese Mn 54.938 43 Technetium Tc (99) 75 Rhenium Re 186 .2 1 07 Neilsbohrium Ns (26 1) 26 Iron Fe 55.8 47 44 Ruthenium Ru 101. 07 76 Osmium Os 190 .2 108 Hassium Hs (26 5) 27 Cobalt Co 58.933 45 Rhodium Rh 1 02. 905 77 Iridium Ir 1 92. 2 109 Meitnerium Mt (26 6) 28 Nickel Ni 58 .71 46 Palladium Pd 106.4 78 Platinum Pt 195.09 29 Copper Cu 63.546 47 Silver Ag 1 07. 868 79 Gold Au 196.9 67 30 Zinc Zn 65.38 48 Cadmium Cd 1 12. 40 80 Mercury Hg 20 0.59 5 Boron B 10.811 13 Aluminum Al 26 .9815 31 Gallium Ga 69. 72 3 49 Indium In 114. 82 81 Thallium Ti 20 4. 37 6 Carbon C 12. 01 12 14 Silicon Si 28 .086 32 Germanium Ge 72 . 59 50 Tin Sn 118.69 82 Lead Pb 20 7. 19 7 Nitrogen N 14.00 67 15 Phosphorus P 30. 973 8 33 Arsenic As 74 .9 92 51 Antimony Sb 121 .75 83 Bismuth Bi 20 8.980 60 Neodymium Nd 144 .24 59 Praseodymium Pr 140.9 07 58 Cerium Ce 140. 12 . opposite sides of the tibia and act as antagonists. Atlas B 1. f 11. y 21 . k 2. b 12. m 22 . d 3. k 13. n 23 . f 4. p 14. e 24 . b 5. h 15. g 25 . a 6. z 16. v 26 . u 7. o 17. f 27 . j 8. x 18. c 28 . i 9.