Topics: Developmental psychology, Jean Piaget, Secondary sex characteristic Pages: 16 (3114 words) Published: January 29, 2013
General Psychology Class 1IT-A, 1IT-B, 2CpE 3Archi, 4Archi, 2CS, 4CS Don Bosco Technical College

The Developing Person
Developmental Psychology
study of physical, cognitive, and social changes across the life span

In the woman’s body, hormones are causing a follicle (egg container) in one of her ovaries to ovulate – that is, to rupture and release an egg cell, or ovum. When released, the ovum begins a slow voyage down a 4-inch long Fallopian tube to the uterus. It is within this tube that one of millions of sperm cells will fertilize the ovum. The fertilized ovum, or zygote, is 1/175th of an inch across.

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Within nine months, the newly conceived organism develops from a nearly microscopic cell to a neonate (newborn) about 20 inches long. The zygote divides repeatedly as it proceeds on its three to four-day voyage to the uterus. The ball like mass of multiplying cells wanders about the uterus for another three to four days before being implanted in the uterine wall. Implantation takes another week or so.

Germinal stage – the period from conception to implantation – or the period of the ovum. Embryonic stage – lasts from implantation until about the eighth week of development. During this stage, the major body systems take form. The growth of the head is followed by the growth of the organs (heart, lungs, etc.) and finally the extremities. The relatively early maturation of the brain and organ systems allows them to participate in the nourishment and further development of the embryo.

Fourth week – a primitive heart begins to pump blood in an organism that is 1/5 of an inch long. End of second month – the head becomes rounded and facial features distinct – all in an embryo that is about 1 inch long and weighs 1/30th of an ounce. The nervous system also begins to transmit messages By five to six weeks, nondescript sex organs have formed. By about the seventh week, the genetic code (XX or XY) begins to assert itself, causing sex organs to differentiate.

If a Y chromosome is present, testes form and begin to produce androgens (male sex hormones), which further masculinize the sex organs. In the absence of these hormones, the embryo develops sex organs typical of the female, regardless of its genetic code. However, individuals with a male genetic code would be sterile. The embryo is suspended within a protective amniotic sac in the mother’s uterus. The sac is surrounded by a clear membrane and contains amniotic fluid. The fluid is some sort of a natural air bag, allowing the child to move or even jerk around without injury.

The embryo is connected to the placenta by the umbilical cord. The placenta is connected to the mother by blood vessels in the uterine wall. Fetal stage – lasts from the beginning of the third month until birth. By end of third month, major organ systems and the fingers and toes have formed. In the middle of the fourth month, the mother usually detects the first fetal movements.

By the end of the sixth month, the fetus moves its limbs so vigorously that mothers often feel that they are being kicked. The fetus opens and shuts its eyes, sucks its thumb, alternates between being awake and asleep, and responds to light. During the last three months, the organ systems of the fetus continue to mature. The heart and lungs become increasingly capable of sustaining independent life. The fetus gains about 5.5 pounds and doubles in length. Newborn boys average about 7.5 pounds, and newborn girls about 7 pounds.

During infancy, dramatic gains in weight and height continue. Babies normally double their birth weight in about 5 months and triple it by their first birthday (Kuczmarski, et al, 2000). Their height increases by about 10 inches in the first year. Children grow another 4 to 6 inches during the second year and gain some 4 to 7 pounds. After that, they gain about...
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