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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.
- Overview
- Types and rates of human growth
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. Meanwhile, height is in most circumstances the best single index of growth, being a measure of a single tissue (that of the skeleton; weight is a mixture of all tissues, and this makes it a less useful parameter in a long-term following of a child’s growth). 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 velocity or rate of growth reflects the child’s state at any particular time better than does the height attained, which depends largely on how much the child has grown in all preceding years. 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.
Britannica Quiz
Characteristics of the Human Body
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. The peak velocity of length is reached at about four months after the mother’s last menstruation. (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.)
Oct 11, 2022 · 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. human development.
Describe human development and its three domains: physical, cognitive, and psychosocial development. Explain key human development issues about the nature of change: continuous/discontinuous, one course/multiple courses, and nature/nurture.
Mar 8, 2023 · Objectives: Describe the stages of growth and development. Review the factors affecting growth and development. Outline the methods for growth measurements and standard screening tools for developmental assessment.
- Palanikumar Balasundaram, Indirapriya Darshini Avulakunta
- 2023/03/08
- 2021
Learning Outcomes. Describe human development and its three domains: physical, cognitive, and psychosocial development. Explain key human development issues about the nature of change: continuous/discontinuous, one course/multiple courses, and nature/nurture. Describe the basic periods of human development. Defining Human Development. Figure 1.
Development is all of the changes the body goes through in life. Development includes the process of differentiation , in which unspecialized cells become specialized in structure and function to perform certain tasks in the body.
