User:Sharma kaur/Sandbox

LIFE SPAN DEVELOPMENT === == __TOC

DEVELOPMENTAL CHANGES Stages in the life span CHARACTERISTICS OF PRENATAL DEVELOPMENT period of prenatal development Timetable of prenatal development__

LIFE SPAN DEVELOPMENT
The term lifespan development refers to age-related changes that occur from birth, throughout a persons' life, into and during old age.

MEANING OF DEVELOPMENTAL CHANGES
The term development means a progressive series of changes that occur as a result of maturation and experience. To understand the pattern of development, certain fundamental and predictable facts must be taken into consideration. They are

a. Early foundation are critical: Attitude, habits and patterns of behaviour established during the early years of age, determine to a large extent how individuals will be able to adjust to life as they grow older. The foundations laid    duringthe first two years of life are the most critical.

b. Role of maturation and learning in development: Maturation & learning play important roles in development. Maturation is the unfolding of the individual’s interest traits -functions which are common to the human race such as crawling, sitting, walking,etc.

Learning is development that comes from exercise and efforts on the individual’s part- these are specific to the individual like writing,driving, swimming, etc.

c. Development follows a definite and predictable pattern: These are orderly pattern of physical, motor, speech,intellectual development eg: laws of developmental direction -the “cephalocaudal law” which maintains that development spreads over the body from head to feet and the “proxim-odistal law” which maintains that development spreads outward from the   central axis of the body to the extremities.

d. All individuals are different: Every person is biologically and genetically different from every other, even in case of identical twins and there is evidence that differences increase rather than decrease as children grow from childhood into adolescence and eventually to old age.

e. Each phase of development has characteristic behavior: During the growing up years, the patterns are marked by period of equilibrium, when individuals adapt or adjust easily to environmental demands and as a result, make good personal and social adjustments. The other is periods of disequilibrium, when they experience difficulties in adaptation and as a result make poor personal and social adjustments.

f. Each phase of development has hazards: There is evidence that each period in the life span has associated with it certain developmental hazards or problems, Which can be physical, psychological, social or environmental in origin and these inevitably involve adjustment problems. Awareness of these hazards will help people to cope with these and adjust better.

g. Development is aided by stimulations: Stimulation in the form of support and encouragement given to children by parents and elders will aid development in children in the desired direction.

h. Development is affected by cultural changes: Individual’s development and behavior is molded to conform to cultural standard and ideals and life style. Changes in these standards affect the development pattern.

i. Social expectation for every stage of development: Every cultural group expects its members to master certain essential skills and acquire certain approved pattern. These are referred to as “developmental tasks” - a task which arises at or about a certain period in the life of the individual. Successful achievement of these tasks will lead to happiness and to success with later tasks. j. Traditional beliefs about people of old ages: These beliefs about physical and psychological characteristics affect the judgment of others as well as their self evaluation. This is true of the traditional beliefs about sex differences and the cultural stereotype of males & females at all ages. So long as they persist, they have a profound influence on the developmental pattern.

Stages in the life span
a) Prenatal period - conception to birth b) Infancy - birth to the end of the second week c) Babyhood - end of the second week to end of the second year. d) Early childhood - two to six years e) Late childhood - Six to ten years or twelve years f) Puberty or preadolescence - Ten or twelve to thirteen or fourteen years g) Early adulthood - eighteen to forty years h) Middle age - forty to sixty years i) Old age - sixty to death.

CHARACTERISTICS OF THE PRENATAL PERIOD
This is the first developmental period in the life span, though the period is short it is in many respects one of the most important period. It begins at conception and ends at birth approximately 270 to 280 days in length or of calendar 9 months. This has six important characteristics.

The prenatal period has six important characteristics, each of which has a lasting effect on development during the life span. They are 1. The hereditary endowment which serves as the foundation for later development is fixed once and for all, at this time.While favourable or unfavourable conditions both before and after birth may and probably will affect to some extent the physical and psychological traits that make up this hereditary endowment, that changes will be quantitative and not qualitative. 2. Favorable condition in the mother’s body can foster the development of hereditary potentials while unfavorable conditions can stunt their development. 3. The sex of the newly created individual is fixed at the time of conception and conditions within the mother’s body will not affect it. 4. Proportionally greater growth and development take place duringthe prenatal period than at any other time throughout the individual’s entire life. During these nine months, the individual grows from a    microscopically small cell to an infant who measures approximatel twenty inches in length and weigh on an      average 3-3.5 kg.Development is rapid. 5. The prenatal period is a time of many hazards, both physical and psychological. This can have a marked effect on the pattern of later development or may even bring development to an end. 6. How life begins - New life begins with the union of a male sex cell and a female sex cell. These sex, cells are developed in the reproductive organs. There are twenty three pairs of chromosomes in each mature sex cell and each chromosome contains genes - the true carriers of heredity. At the time of conception four important conditions are determined that influence the individual’s later development.

The four important conditions are
1. Hereditary endowment is the determination of the newly created individual’s hereditary. Hereditary places limits beyond which individuals cannot go and it is entirely a matter of chance in the number of chromosomes from the maternal or paternal side that will be passed on to the child.

2. Sex - Determination of sex is the second important happening at the time of conception. Sex depends on the kind of spermatozoon that unites with the ovum.

3. Number of offspring's - when a ripe ovum is fertilized by one spermatozoon, the result will be a      singleton, unless the fertilized ovum splits into two or more distinct parts during the early stages of cell cleavage, when this happens, the result will be identical twins, triplets or other multiple births. When two or more ova are released simultaneously and are fertilized by different spermatozoa, the result will be non identical twins, triplets or other multiple births.

== 4. Ordinal position - The fourth thing happening at the time of conception is the establishment, of the new child’s ordinal position among siblings, such as the role the individual plays in the family and the treatment received from significant family members and their attitudes. ==

Periods of Prenatal Development
The prenatal period is ten lunar months of twenty eight days each in length or nine calendar months. This can vary from 180 to 334 days. Because prenatal development is orderly and predictable, it is possible to give a timetable of the important development taking place during this period. This period is divided into three stages.

The size of the zygote - that of a pinhead – remains unchanged because it has no outside source of  nourishment; it is kept alive by yolk in the ovum. As the zygote passes down the fallopian tube to the uterus, it divides many times and separates into an outer and an inner layer. The outer layer later develops into the placenta, the umbilical cord, and the amniotic sac, and the inner layer develops into a new human being.

About ten days after fertilization, the zygote becomes implanted in the uterine wall.

Period of the Embryo (end of the second week to end of the second lunar month)
The embryo develops into a miniature human being. Major development occurs, in the head region first and in the extremities last. All the essential features of the body, both external and internal, are established. The embryo begins to turn in the uterus, and there is spontaneous movement of the limbs.

=
The placenta, the umbilical cord, and the amniotic sac develop; these protect and nourish the embryo. At the end of the second prenatal month, the embryo weighs, on an average,33 gm (1 1/4 ounces ) and measures in length 1 1/2 inches. =====

Period of the Fetus (end of the second lunar month to birth)
Changes occur in the actual or relative size of the parts already formed and in their functioning. No new features appear at this time. By the end of the third lunar month, some internal organs are well enough developed to begin to function. Fetal heartbeat can be detected by about the fifteenth week. By the end of the fifth lunar month, the different internal organs have assumed positions nearly like the ones they will have in the adult body. Nerve cells, present from the third week, increase rapidly in number during the second, third, and fourth lunar months. Whether or not this rapid increase will continue and depend upon conditions within the mother’s body such as malnutrition, which adversely affects nerve cell development - especially during the latter months of the prenatal period. Fetal movements usually appear first between eighteen and twenty- two weeks and then increase rapidly up to   the end of the ninth lunar month when they slow down because of crowding in the amniotic sac and pressure on the fetal brain as the fetus takes a head-down position in the pelvic region in preparation for birth. These fetal movements are of different kinds - rolling and kicking and short or quick movements.

By the end of the seventh lunar month, the fetus is well enough developed to survive, should it be born prematurely. By the end of the eighth lunar month the fetal body is completely formed, though smaller than that of a normal, full-term infant.