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DVD ilustrado plurilingüe

La biología del desarrollo prenatal

6 meses hasta el nacimiento

THE BIOLOGY OF PRENATAL DEVELOPMENT

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Capítulo 43 5 a 6 meses (20 a 24 semanas): responde al sonido; cabello y piel; edad de viabilidad

Reproducir película \| Ver fotos instantáneas	By 24 weeks the eyelids reopen and the fetus exhibits a blink-startle response. This reaction to sudden, loud noises typically develops earlier in the female fetus.
Reproducir película \| Ver fotos instantáneas	Several investigators report exposure to loud noise may adversely affect fetal health. Immediate consequences include prolonged increased heart rate, excessive fetal swallowing, and abrupt behavioral changes. Possible long-term consequences include hearing loss.
Reproducir película \| Ver fotos instantáneas	The fetal respiratory rate can rise as high as 44 inhalation-exhalation cycles per minute.
Reproducir película \| Ver fotos instantáneas	During the third trimester of pregnancy, rapid brain growth consumes more than 50% of the energy used by the fetus. Brain weight increases between 400 and 500%.
Reproducir película \| Ver fotos instantáneas	By 26 weeks the eyes produce tears. The pupils respond to light as early as 27 weeks. This response regulates the amount of light reaching the retina throughout life.
Reproducir película \| Ver fotos instantáneas	All components required for a functioning sense of smell are operational. Studies of premature babies reveal the ability to detect odors as early as 26 weeks after fertilization. Placing a sweet substance in the amniotic fluid increases the rate of fetal swallowing. In contrast, decreased fetal swallowing follows the introduction of a bitter substance. Altered facial expressions often follow.
Reproducir película \| Ver fotos instantáneas	Through a series of step-like leg motions similar to walking, the fetus performs somersaults.
Reproducir película \| Ver fotos instantáneas	The fetus appears less wrinkled as additional fat deposits form beneath the skin. Fat plays a vital role in maintaining body temperature and storing energy after birth.
Capítulo 44 7 a 8 meses (28 a 32 semanas): discriminación de sonidos, estados de comportamiento

Reproducir película \| Ver fotos instantáneas	By 28 weeks the fetus can distinguish between high- and low-pitched sounds.
Reproducir película \| Ver fotos instantáneas	By 30 weeks, breathing movements are more common and occur 30 to 40% of the time in an average fetus.
Reproducir película \| Ver fotos instantáneas	During the last 4 months of pregnancy, the fetus displays periods of coordinated activity punctuated by periods of rest. These behavioral states reflect the ever-increasing complexity of the central nervous system.
Capítulo 45 Las extremidades y la piel

Reproducir película \| Ver fotos instantáneas	By approximately 32 weeks, true alveoli, or air "pocket" cells, begin developing in the lungs. They will continue to form until 8 years after birth.
Reproducir película \| Ver fotos instantáneas	At 35 weeks the fetus has a firm hand grasp.
Reproducir película \| Ver fotos instantáneas	Fetal exposure to various substances appears to affect flavor preferences after birth. For instance, fetuses whose mothers consumed anise, a substance which gives licorice its taste, showed a preference for anise after birth. Newborns without fetal exposure disliked anise.
Capítulo 46 9 meses hasta el nacimiento (36 semanas hasta el nacimiento)

Reproducir película \| Ver fotos instantáneas	The fetus initiates labor by releasing large amounts of a hormone called estrogen and thus begins the transition from fetus to newborn. Labor is marked by powerful contractions of the uterus, resulting in childbirth.
Reproducir película	From fertilization to birth and beyond, human development is dynamic, continuous, and complex. New discoveries about this fascinating process increasingly show the vital impact of fetal development on lifelong health. As our understanding of early human development advances, so too will our ability to enhance health - both before and after birth.