Introduction to Growth and Development
Introduction
 Human life proceeds in stages from infancy to
adulthood to senescence.
 All human beings share the same mechanisms of
growth and development and proceed through the
same stages of life.
 The rate of maturation and the final outcome are
widely variable because of the expensive and diverse
influences on each individual.
Introduction
 Growth may be defined as a physiological process by which
the organism assimilates or transforms essential, nonliving
nutrients into living protoplasm. Growth involves the
incorporation of new materials.
 Development is defined as a physiological process by which
the individual progresses from an undifferentiated state to
a highly organized and functional capacity. Development
implies an increase in skill and in complexity of function.
 As growth is measured in pounds and inches, development
is measured in abilities
Patterns of Growth and Development:
 The genetic code determines the rate of the growth and
development of the various body parts, which occur in
synchrony with overall growth and development. For
example, at birth the lower limbs of the infant are less well
developed than the upper limbs.
 During the prenatal and postnatal periods, growth and
development follow a cephalocaudal pattern, that is
development proceeds from head (cephalo) to toe (caudal).
The head matures before the neck, the neck before the
chest, the chest before the pelvis, and so on.
Patterns of Growth and Development:
 The cephalocaudal and proximodistal patients of growth
and development are evident in the motor development of
the infant. He rolls over before he can sit; his arm and chest
development enable this maneuver. As his trunk and legs
develop.
Stages of Growth and Development:
 The human life span can be divided into two distinct
biological periods, prenatal and postnatal.
 The prenatal period includes three stage the ovum,
embryo, and fetus.
 Postnatal life begins with birth and proceeds through the
neonatal period, infancy,
adulthood, and sensescence.
childhood,
adolescence,
 The progression from one stage to the next is dependent
upon completion of the previous stage.
Characteristics of Growth and Development:
 Directional patterns:
 Are fundamental to the growth of all humans.
 Cephalocodal development:

Proceeds from head to toe. The infant can raise the head
before he can sit and gains control of the trunk before
walking.
 Proximo- distal development :

Proceeds from inner to outer. the infant is able to control the
trunk before arms .
 General to specific development:

The infant grasps with the hands before pinching with fingers.
Characteristics of Growth and Development:
 Metabolic rate:
 In children is higher than in adults, so infants require
more calories, minerals and vitamins and fluid in
proportion to weight and height than do adults.
 The body surface area of young children is far greater in
relation to body weight than that of adult.
 The young child loses more fluid from the pulmonary
system and skin.
Characteristics of Growth and Development:
 Bone growth:
 It is one of the best indicators of biological age.
 Bone age can be determined from x-ray films.
 Though ossification cartilage is converted to bone.
 Growth of long bones continues until epipheseal fusion
occurs.
Characteristics of Growth and Development:
 Critical Periods:
 Are periods when environmental events have their
maximal effect on the child's development
 During the first 3 months of pregnancy, certain viruses
and drugs are known to cause congenital anomalies.
Characteristics of Growth and Development:
 Growth Standards:
 Standards have been developed to:



Compare the measurement for any one child with those for
other children of the same age, sex & race.
Compare that child's present measurements with his own
former sate of growth.
Percentile charts are customarily designed and divided into 7
percentile levels 95 th , 90 th , 75 th , 50 th , 25 th 10 th and 5 th ,
Characteristics of Growth and Development:
 Selected
Factors
Development :
That
Influence
Growth
&
 Genetic & Hereditary Traits:
 Inherited traits as hair color, height ... etc...
 Genetic disorders as the lasemia , achondroplasia ... etc....
 Nationality & race:
 Japanese ---- (was) short, African ----- tall
 Congenital anomalies:
 As congenital heart diseases.
 Nutritional factors:
 as growth failure is an important feature of protein – energy
malnutrition.
 Chronic diseases:
 as tuberculosis.
Prenatal Period:
 The most rapid growth and development in the
human life cycle occurs in the prenatal period.
 During the embryonic period, the formation of organs
occurs rapidly. In the early fetal period the fetus's
length increases rapidly.
 During the last trimester, the fetus makes rapid gains
the weight.
Neonatal Life:
 The neonatal period is defined as the first month of
life.
 The first 24 hours of life comprise the most significant
time of this period, as the neonate must take the
transition from an intrauterine to atmospheric
environment. Infant mortality is highest during this
transition.
Infancy:
 Infancy is a period of rapid growth and development.
 During the first three months of life, the infant gains an
average of two pound per month; by five months of age, the
birth weight has doubled.
 The infant also grows rapidly in height. By the end of the
first year the infant's length is 50 percent greater than at
birth.
 During this period, the infant brain grows more rapidly
than the whole body and attains nearly adult size by two
years age.
Childhood:
 The preschool years (age 2 to 6) and the school years
(age 6 to 12) represents a period of relatively slow
growth.
 The
annual increment in weight averages
approximately 5 lb until the ninth or tenth birthday.
 The height increment during the school years is
approximately 2 in each year. During this period, the
child's social world expands as he enters school.
Adolescence:
 The adolescent period comprises the years in which
the child "grows up," It is a period of profound changes
in physical , mental and emotional development.
 The period is marked by an accelerated gain in weight
and height.
Adulthood and Aging:
 The adult years are a period of competency and ability.
 Unlike the development stages, the adult years do not
have a sequence of precisely timed physiological
events. This is also true of the aging years from 65
years until death.
Stages in the Life Cycle
Period
Approximate
Age on Stage
Embryonic
First trimester of
prenatal life
Early fetal
Accelerated growth;
Second trimester
elaboration of structures; early functional
of prenatal life.
activities
Late fetal
Third trimester
of prenatal life
Rapid increase in body mass; completion of
preparation for postnatal life
Parturient
Period of labor
and delivery
Risk of trauma and anoxia; cessation of
placental function
Neonatal
and early
infancy
First month of
postnatal life
Postnatal adjustments in circulation;
initiation of respiration and other functions.
Some Characteristics
Rapid differentiation; establishment of
systems and organs
Stages in the Life Cycle
Period
Middle
infancy
Approximate
Age on Stage
Some Characteristics
1 mo to 1 yr
Rapid growth and maturation; maturation of
functions, especially of nervous system
1 to 2 yr
Decelerating growth; Progress in waling and
other voluntary motor activities, and in
control of excretory functions.
Preschool
2 to 6 yr
Slow growth; increased physical activity;
further coordination of functions and motor
mechanisms; rapid learning.
School
Girls : 6 to 10 yr Steady growth; developing skills and
Boys : 6 to 12 yr intellectual processes
Late infancy
Stages in the Life Cycle
Period
Approximate
Age on Stage
Prepubertal
(late school or Girls 10 to 12 yr
early
Boys : 12 to 14 yr
adolescent)
Pubrtal
(adolescence
proper)
Postpubertal
Girls : 12 to 14 yr
Boys : 14 to 16 yr
Some Characteristics
Accelerating growth; rapid weight gain; early
adolescent endocrine and sex organ changes
Maturation of secondary sex characteristics;
Maximum postnatal growth increase;
decelerating and terminal growth; rapid
Girls : 14 to 18
muscle growth and increased skills; rapid
yr
growth and maturing functions of sex
Boys 16 to 20 yr
organs; need for self-reliance and
independence.
Hormonal influence
development:
on
growth
and
 The growth and development of an individual is
influenced by four major sources of hormones:
 the central nervous system, and
 the thyroid gland, and
 the adrenal gland, and
 the gonadal gland.
Hormonal influence
development:
on
growth
and
 Although the hormones have different chemical
structures and are produced by different organs, they
all influence growth and development by stimulating
protein synthesis.
 It is hypothesized that each hormone has its major
effect on growth and development at a particular
period of life.
Hormonal influence
development:
on
growth
and
 Growth Hormone:
 Growth hormone is secreted by the anterior portion of
the pituitary gland in response to growth hormone
releasing factor, which is produced by the
hypothalamus; under the influence of various stimuli,
the hypothalamus controls the anterior pituitary and,
thereby, the release of growth hormone. Thus, the
pituitary is an intermediary gland.
Hormonal influence
development:
on
growth
and
 Growth Hormone:
 Growth hormone is chiefly influential in protein
synthesis. At the cellular level, growth hormone
stimulates increased transport of amino acids into cells
and increased incorporation of amino acids into protein.
 The role of growth hormone in the prenatal period has
not been clearly delineated. The influence of growth
hormone brings about an increase in the child’s height
and weight, changes in skeletal proportions and head
and face contours, dental development, and ossification
of the long bones.
Hormonal influence
development:
on
growth
and
 Thyroid Hormones:
 Thyroxine (T4) and triidothyrodine (T3) are the major
thyroid hormones and are secreted by the thyroid gland.
 Their release is regulated by the hypothalamus and the
pituitary gland. The thyroid hormones exert their
influence by stimulating protein synthesis.
 In contrast to growth hormone, thyroid hormones have
a great influence on fetal and neonatal growth. In the
absence of thyroid hormones during this period, there is
a lack of brain growth, probably in both cell number and
cell size.
Hormonal influence
development:
on
growth
and
 Androgens:
 An increase in androgens is felt to be responsible for most of
the growth and development that takes place during
adolescence.
 The androgens exert their influence like growth hormone and
thyroid hormone, i.e. by stimulating protein synthesis. They
are responsible for overall growth and skeletal and muscular
maturation.
 Testosterone is the principal androgen produced by the testes.
Dehydroepiandrosterone is the principal androgen produced
by the adrenal cortex. The androgens and estrogens are
responsible for sexual maturation during adolescence.
Heredity and Environment:
 The human organism experiences a lengthy period of
growth and development, influenced by internal
factors (those that are intrinsic of the individual, i.e.,
genetic potential) and external factors (those that are
outside of the individuals, i.e., environmental
influences).
 As has been said, the final outcome of growth and
development is a result of the dynamic interplay of
genetic potential and environmental factors.
Genetic Potential:
 The information stored in the genes exerts a tremendous
influence on the individual’s maturation. Genetic factors affect
the individual’s rate of growth, the time of the onset of the
adolescent growth spurt, and the final size and shape of the
body.
 Genetic factors play a leading part in the growth difference
between males and females. Boys and girls have different
patterns of growth and development, and an obvious difference
in final outcome.
 Girls
mature more rapidly than boys throughout the
developmental years. Adolescence begins sooner for girls, and
they attain sexual maturity and maximum height approximately
two year earlier than boys.
Genetic Potential:
 Girls begin their growth spurt at approximately age 10
to 11 years and will have reached adult height by about
16 years.
 Boys begin their growth spurt at age 12 to 13 years and
do not each adult stature until 18 years of age.
 Genetic factors are also influential in the differences
seen in different ethnic groups.
Environmental Factors:
 The environment supplies the external factors that make growth
and development possible.
 Environmental factors include temperature, nutrition, drugs,
infections, radiation, and so on. These external factors are
influential throughout the life span.
 The impact of an environmental factor on growth and
development is dependent on the characteristics, intensity,
duration, and timing of the factors. The organism as a whole,
and specific organs, is particularly susceptible to environmental
factors during specific stages called critical periods.
 The central nervous system is very susceptible to environmental
factors during the fetal period.
Skeletal Growth:
 Skeletal growth is commonly taken as an index of overall
growth and development. Height, a reflection of an
individual’s skeletal growth, is a common clinical measure.
Bone age may also be used as a clinic measurement of
physiological maturity.
 Bone is a specialized tissue that supports the body and
protects vital organs. The human skeleton exits first in the
form of connective tissue, then cartilage, and finally bone.
The adult skeleton is composed of bone with no remnants
of the original membranous skeleton. The closure of the
fontanelles in infancy demonstrates this progression from
connective tissue to bone in skeletal development.
Skeletal Growth:
 During childhood, cartilage is found throughout the
skeleton. The length of the skeleton grows by dint of
the proliferation of cartilage. The cartilage changes to
bone by the process of ossification. It is through the
two processes of cartilage proliferation and ossification
that the bones grow.
 Cartilage is produced in the metaphyses of bones and
in the cartilage plate. Ossification proceeds from the
epiphysis (end) of the bone, which contains the
ossification centers.
Skeletal Growth:
 Skeletal growth and development involves the continual growth
of ossification centers; skeletal maturation is initiated by the
appearance of ossification centers and is terminated when these
centers are fused. The individual has approximately 400
ossification centers at birth, ad twice as many by maturation.
New ossification centers appear according to a regular schedule.
The growth of new ossification centers is under hormonal
control; growth hormone seems to have the most influence on
the growth of new ossification centers.
 The stages of bone growth occur at regular intervals that vary
little between individuals. This relative uniformity permits the
use of bone age measurement as a reliable index of maturation.
Skull Growth:
 The skull is large at birth because of the relatively large
size of the brain. After birth, the skull continues to
grow in order to accommodate the very rapid further
growth of the brain.
 In the first two years of life, the skull’s capacity grows
from 400ml to 950ml and its circumference increases
from about 33cm to 47cm.
Skull Growth:
 At birth, the bones that comprise the cranial vault are
separated by gaps filled with fibrous connective tissue; the
gaps allows the bones to slide over each other to some
extent as the neonate passes through the mother’s narrow
birth canal.
 As ossification of the fibrous connective tissue proceeds,
the individual bones come into contact with each other
along a series of fibrous joints known as sutures. It is at the
sutures that skull growth takes place. Skull growth will
continue until after puberty, accommodating the growing
brain. After skull growth stops, the sutures will be
obliterated by their ossification and fusing together.