Order of prenatal development |
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zygote, cleavage, morula, blastocyst, embryo, fetus |
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process that makes it possible for sperm to penetrate the egg is called |
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capacitation |
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In the slow block to polyspermy, sperm penetration releases an inflow of ___________, which in turn stimulates the ________. |
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Ca2+; cortical reaction |
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In the fast block to polyspermy, binding of sperm opens up _________ channels, which depolarizes the egg membrane and _________ |
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Na+; prevents the entrance of any more sperm |
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The optimal "window of opportunity" to conceive a child is |
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a few days before ovulation to less than a day after |
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The spheroidal stage of early prenatal development with about 16 to 64 cells is called a/an |
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Morula |
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Twins produced when a single egg is fertilized are called _____________ twins, and twins produced from two eggs ovulated at the same time are called ___________ twins |
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monozygotic; dizygotic |
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In the blastocyst, the trophoblast will become ____________, whereas the embryoblast will become __________ |
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part of the placenta; the embryo |
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Primary germ layers are formed during |
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gastrulation |
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Mesenchyme gives rise to |
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muscle, bone and blood |
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During implantation, the trophoblast divides into a deep layer, the _________, composed of individual cells, and a superficial layer, the ___________, composed of a multinucleate mass of cytoplasm |
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cytotrophoblast; syncytiotrophoblast |
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By the time the conceptus arrives in the uterus |
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it consists of 16 or more cells |
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Out of the 300 million ejaculated sperm, only about ____________ reach the vicinity of the egg |
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3,000 |
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Prior to ejaculation, __________ in the sperm plasma membrane prevents premature release of ______________ |
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cholesterol; acrosomal enzymes |
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These are derivatives of ectoderm except |
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the dermis |
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The first body cavity is called the |
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coelom |
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By the end of 8 weeks, the individual is considered a fetus because |
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all of the organ systems are present |
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The ___________ completely encloses the embryo and provides a stable environment for it. |
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amnion |
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The ___________ encloses all the rest of the membranes and the embryo |
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chorion |
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The embryonic membrane that forms the fetal portion of the placent |
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the villous chorion |
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As it implants, the conceptus is nourished by means of |
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trophoblastic nutrition |
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The vessel that provides oxygenated blood to the placenta is |
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a maternal artery |
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In fetal circulation, the __________ bypasses the liver and the _________ bypasses the lung |
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ductus venosus; ductus arteriosus |
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In fetal circulation, blood bypasses the lungs by flowing through |
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the foramen ovale and ductus arteriosus |
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Which of the following major events of prenatal development happens first? -eyes are fully open-body covered with lanugo-bone calcification begins-central nervous system begins to form-meconium accumulates in intestines |
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the central nervous system begins to form |
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Oxygenated blood reaches the fetus through the |
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umbilical vein |
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The embryonic membranes include all of the following except the |
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placenta |
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_______ pass(es) from the maternal blood to the fetal blood; while fetal _________ pass(es) the other way |
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Oxygen and nutrients; wastes |
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The digital rays of a fetus give rise to |
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fingers and toes |
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The first 6 weeks of postpartum life constitute |
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the neonatal period |
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The fossa ovalis is a remnant of the ___________ of the fetus |
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foramen ovale |
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During birth, an infant is normally stimulated to breathe by |
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CO2 accumulating in the baby's blood |
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Which organ system shows the greatest anatomical change in the transitional period after birth? |
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Circulatory |
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Infant respiratory distress syndrome (IRDS) is caused by |
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deficiency of pulmonary surfactant. |
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Which organ system faces the greatest physiological challenge in the transitional period after birth? |
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Respiratory |
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A teratogen is most likely to cause |
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a deformity of the limbs. |
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These are have potentially teratogenic effects except-smoking-alcohol-infectious diseases-sunlight-x-rays |
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sunlight. |
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Down syndrome (trisomy-21) results from |
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nondisjunction. |
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The most likely outcome of nondisjunction is the production of a gamete receiving |
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22 chromosomes. |
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Only autosomal trisomies involving chromosomes 13, 18, and 21 are survivable. why would this be? |
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These are relatively gene-poor chromosomes. |
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Urine retention is a greater problem for elderly men than for elderly women because men |
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usually develop benign prostatic hyperplasia. |
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Muscular weakness tends to develop in old age for all of the following reasons except:-aged muscle has less glycogen, myoglobin, and creatine phosphate.-there are fewer motor neurons in the spinal cord.-aged muscle fibers have fewer myofibrils.-there are fewer and smaller mitochondria.-myocytes do not synthesize myosin anymore. |
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myocytes do not synthesize myosin anymore. |
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Older people may require lower drug doses than younger people because |
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they have lower rates of renal clearance. |
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Telomeres |
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are DNA segments at each end of a chromosome. |
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The observation that there is a limit to how many times a cell can divide is the basis for the |
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replicative senescence theory. |
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Clinical death is widely defined as |
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brain death. |
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Which of the following systems shows the least overall senescence? |
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endocrine system |
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Senescence of the immune system makes older people more subject to cancer and infectious disease because of a decline in |
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antigen-presenting cells and helper T cells. |
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Congenital anomalies can result from all of the following except-an infectious disease in the mother during pregnancy.-genetic disorder-exposure to teratogens during pregnancy-smoking during lactation-smoking during pregnancy |
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smoking during lactation. |
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