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- Human Growth and Development
- What Is Human Development and Why Is It Important?
- Human Growth and Development
- 23: Human Growth and Development
This chapter describes how the human organism grows and develops from fertilization through death. The following stages of life are described in detail: germinal stage, embryonic stage, fetal stage, infancy, childhood, adolescence, and adulthood. Since Vanessa is three months pregnant, they are worried about whether Vanessa was also exposed to lead.
Human Growth and Development pulls together information from leading experts in a variety of fields to create a one-volume resource on the human growth stages, environmental effects, and the research methods scientists should use. This text promises to be a great course-planning guide for instructors in various medical and scientific fields in addition to a thorough reference for further research. Professors, researchers and advanced students in medicine, physiotherapy, human biology and development, and anthropology. Front Matter. Annotated Refs.
Human Growth and Development
Human development , the process of growth and change that takes place between birth and maturity. Human growth is far from being a simple and uniform process of becoming taller or larger. As a child gets bigger, there are changes in shape and in tissue composition and distribution. In the newborn infant the head represents about a quarter of the total length; in the adult it represents about one-seventh. In the newborn infant the muscles constitute a much smaller percentage of the total body mass than in the young adult.
In most tissues, growth consists both of the formation of new cells and the packing in of more protein or other material into cells already present; early in development cell division predominates and later cell filling. Different tissues and different regions of the body mature at different rates, and the growth and development of a child consists of a highly complex series of changes. It is like the weaving of a cloth whose pattern never repeats itself.
The underlying threads, each coming off its reel at its own rhythm, interact with one another continuously, in a manner always highly regulated and controlled. The fundamental questions of growth relate to these processes of regulation, to the program that controls the loom, a subject as yet little understood.
In this section, the height curves of girls and boys are considered in the three chief phases of growth; that is briefly from conception to birth, from birth until puberty , and during puberty. Also described are the ways in which other organs and tissues, such as fat, lymphoid tissue , and the brain, differ from height in their growth curves.
There is a brief discussion of some of the problems that beset the investigator in gathering and analyzing data about growth of children, of the genetic and environmental factors that affect rate of growth and final size, and of the way hormones act at the various phases of the growth process.
Lastly, there is a brief look at disorders of growth. Throughout, the emphasis is on ways in which individuals differ in their rates of growth and development. The changes in height of the developing child can be thought of in two different ways: the height attained at successive ages and the increments in height from one age to the next, expressed as rate of growth per year.
If growth is thought of as a form of motion, the height attained at successive ages can be considered the distance travelled, and the rate of growth, the velocity. The blood and tissue concentrations of those substances whose amounts change with age are thus more likely to run parallel to the velocity rather than to the distance curve. In some circumstances, indeed, it is the acceleration rather than the velocity curve that best reflects physiological events.
In general, the velocity of growth decreases from birth onward and actually from as early as the fourth month of fetal life; see below , but this decrease is interrupted shortly before the end of the growth period. At this time, in boys from about 13 to 15 years, there is marked acceleration of growth, called the adolescent growth spurt. From birth until age four or five, the rate of growth in height declines rapidly, and then the decline, or deceleration, gets gradually less, so that in some children the velocity is practically constant from five or six up to the beginning of the adolescent spurt.
A slight increase in velocity is sometimes said to occur between about six and eight years. This general velocity curve of growth in height begins a considerable time before birth. Age in the fetal period is usually reckoned from the first day of the last menstrual period, an average of two weeks before actual fertilization, but, as a rule, the only locatable landmark.
There is considerable evidence that from about 34 to 36 weeks onward the rate of growth of the fetus slows down because of the influence of the maternal uterus , whose available space is by then becoming fully occupied.
Twins slow down earlier, when their combined weight is approximately the week weight of a single fetus. Babies who are held back in this way grow rapidly as soon as they have emerged from the uterus. Thus there is a significant negative association between weight of a baby at birth and weight increment during the first year; in general, larger babies grow less, the smaller more.
For the same reason there is practically no relation between adult size and the size of that person at birth, but a considerable relation has developed by the time the person is two years old. This slowing-down mechanism enables a genetically large child developing in the uterus of a small mother to be delivered successfully. It operates in many species of animals; the most dramatic demonstration was by crossing reciprocally a large Shire horse and a small Shetland pony.
The pair in which the mother was a Shire had a large newborn foal, and the pair in which the mother was Shetland had a small foal. But both foals were the same size after a few months, and when fully grown both were about halfway between their parents.
The same has been shown in cattle crosses. Poor environmental circumstances, especially of nutrition, result in lowered birth weight in the human being. This seems chiefly to be caused by a reduced rate of growth in the last two to four weeks of fetal life, for weights of babies born in 36 or 38 weeks in various parts of the world in various circumstances are said to be similar.
Mothers who, because of adverse circumstances in their own childhood , have not achieved their full growth potential may produce smaller fetuses than they would have, had they grown up in better circumstances. Thus two generations or even more may be needed to undo the effect of poor environmental circumstances on birth weight.
The great rate of growth of the fetus compared with that of the child is largely due to the fact that cells are still multiplying. The proportion of cells undergoing mitosis the ordinary process of cell multiplication by splitting in any tissue becomes progressively less as the fetus gets older, and it is generally thought that few if any new nerve cells apart from the cells in the supporting tissue, or neuroglia and only a limited proportion of new muscle cells appear after six postmenstrual months, the time when the velocity in linear dimensions is dropping sharply.
The muscle and nerve cells of the fetus are considerably different in appearance from those of the child or adult. Both have little cytoplasm cell substance around the nucleus. In the muscle there is a great amount of intercellular substance and a much higher proportion of water than in mature muscle.
The later fetal and the postnatal growth of the muscle consists chiefly of building up the cytoplasm of the muscle cells; salts are incorporated and the contractile proteins formed.
The cells become bigger, the intercellular substance largely disappears, and the concentration of water decreases. This process continues quite actively up to about three years of age and slowly thereafter; at adolescence it briefly speeds up again, particularly in boys, under the influence of androgenic male sex hormones. In the nerve cells cytoplasm is added and elaborated, and extensions grow that carry impulses from and to the cells—the axons and dendrites, respectively.
Thus postnatal growth, for at least some tissues, is chiefly a period of development and enlargement of existing cells, while early fetal life is a period of division and addition of new cells.
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What Is Human Development and Why Is It Important?
Human development , the process of growth and change that takes place between birth and maturity. Human growth is far from being a simple and uniform process of becoming taller or larger. As a child gets bigger, there are changes in shape and in tissue composition and distribution. In the newborn infant the head represents about a quarter of the total length; in the adult it represents about one-seventh. In the newborn infant the muscles constitute a much smaller percentage of the total body mass than in the young adult. In most tissues, growth consists both of the formation of new cells and the packing in of more protein or other material into cells already present; early in development cell division predominates and later cell filling.
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In the context of the physical development of children, growth refers to the increase in the size of a child, and development refers to the process by which the child develops his or her psychomotor skills. The period of human growth from birth to adolescence is commonly divided into the following stages:. Growth curves are used to measure growth. The distance curve is a measure of size over time; it records height as a function of age and gets higher with age. The velocity curve measures the rate of growth at a given time for a particular body feature such as height or weight. The height velocity curve is highest in infancy, up to two years of age, with more consistent annual growth afterwards and increases again at puberty.
Human Growth and Development
Imagine two children born in the same town and the same year to families with similar socioeconomic statuses. One child grows up to be assertive and confident, while the other grows up to be timid and shy. The study of the stages of human development can help explain the reasons for these differences and much more. What is human development, exactly?
Development of the human body is the process of growth to maturity. The process begins with fertilization , where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosis and cell differentiation , and the resulting embryo then implants in the uterus , where the embryo continues development through a fetal stage until birth.
What aspects of ourselves change and develop as we journey through life? We move through significant physical, cognitive, and psychosocial changes throughout our lives—do these changes happen in a systematic way, and to everyone? How much is due to genetics and how much is due to environmental influences and experiences both within our personal control and beyond? Is there just one course of development or are there many different courses of development? Figure 1.
Publisher: College of the Canyons.
23: Human Growth and Development
Но он не искал глазами убийцу. Жертва всегда ищет глазами убийцу. Она делает это инстинктивно. Фонтейна эти слова озадачили.
Стратмор разработал план… и план этот Фонтейн не имел ни малейшего намерения срывать. ГЛАВА 75 Пальцы Стратмора время от времени касались беретты, лежавшей у него на коленях. При мысли о том, что Хейл позволил себе прикоснуться к Сьюзан, кровь закипела в его жилах, но он помнил, что должен сохранять ясную голову, Стратмор с горечью признал, что сам отчасти виноват в случившемся: ведь именно он направил Сьюзан в Третий узел. Однако он умел анализировать свои эмоции и не собирался позволить им отразиться на решении проблемы Цифровой крепости. Он заместитель директора Агентства национальной безопасности, а сегодня все, что он делает, важно, как. Его дыхание стало ровным.
➢ Development is possible without growth. PRINCIPLES OF HUMAN DEVELOPMENT. Developmental psychologists believe that knowledge of an accurate.
Да уж, - застонал. - Чуточку. - Это как будто деление на ноль. - Что. - Деление на ноль, - сказала она, пробегая глазами остальные данные. - Средняя цена определяется как дробь - общая стоимость, деленная на число расшифровок.
Чатрукьян пнул ногой урну и выругался вслух - благо лаборатория была пуста: - Диагностика, черт ее дери. С каких это пор заместитель директора начал действовать в обход фильтров. Сотрудникам лаборатории платили хорошие деньги, чтобы они охраняли компьютерные системы АНБ, и Чатрукьян давно понял, что от него требуются две вещи: высочайший профессионализм и подозрительность, граничащая с паранойей. Черт возьми! - снова мысленно выругался. - Никакая это не паранойя.
Десяток компьютерных терминалов располагались напротив видеоэкрана, занимавшего всю дальнюю стену площадью девять на двенадцать метров. На экране стремительно сменяли друг друга цифры и диаграммы, как будто кто-то скользил рукой по клавишам управления. Несколько операторов очумело перебегали от одного терминала к другому, волоча за собой распечатки и отдавая какие-то распоряжения.
Там открывался вид на стоянку автомобилей агентства, а из окна комнаты для заседаний был виден внушительный ряд корпусов АНБ - в том числе и купол шифровалки, это вместилище высочайших технологий, возведенное отдельно от основного здания и окруженное тремя акрами красивого парка. Шифровалку намеренно разместили за естественной ширмой из высоченных кленов, и ее не было видно из большинства окон комплекса АНБ, а вот отсюда открывался потрясающий вид - как будто специально для директора, чтобы он мог свободно обозревать свои владения. Однажды Мидж предложила Фонтейну перебраться в эту комнату, но тот отрезал: Не хочу прятаться в тылу. Лиланд Фонтейн был не из тех, кто прячется за чужими спинами, о чем бы ни шла речь. Мидж открыла жалюзи и посмотрела на горы, потом грустно вздохнула и перевела взгляд на шифровалку.
Лицо Стратмора из багрового стало пунцовым.
Мидж, - сказал Бринкерхофф, - Джабба просто помешан на безопасности ТРАНСТЕКСТА. Он ни за что не установил бы переключатель, позволяющий действовать в обход… - Стратмор заставил. - Она не дала ему договорить.