3. Growth and Development

Question 1

What is Growth?

Answer 1

the progressive development of a living being or part of an organism from its earliest stage to maturity, including the attendant increases in size

Not all parts of the human body grow at the same rate, nor do they all stop growing simultaneously.
The body does not retain the same proportions throughout growth and the relative weights of given tissues and organs do not remain constant.

Question 2

Neonatal Period

Answer 2

extends from birth to the end of four weeks

Question 3

Infancy

Answer 3

extends from the end of the neonatal period at four weeks until two years of age. Infancy is characterized by tremendous growth, increased coordination, and mental development.

Question 4

Childhood

Answer 4

the period of growth and development extending from infancy to adolescence, at which time puberty begins.

varies because puberty begins at different ages for different
people.

Question 5

Adolescence

Answer 5

the period of growth and development between childhood and adulthood.

It begins around the age of nine in girls and the age of eleven years in boys.

The end of adolescence is approximately 17-18 years

Question 6

Adulthood

Answer 6

the period of life beyond adolescence. An adult has reached maximum physical stature as determined by genetic, nutritional, and environmental factors.

Question 7

Distance curve

Answer 7

measurements taken at intervals are plotted against time to produce a graph of progress.

Question 8

Velocity curve

Answer 8

increments in growth are plotted against time to show the variation in the rate of growth with time.

Question 9

Longitudinal data

Answer 9

the growth curve is derived from a single individual or from repeated measurements on the same group of individuals over a period of many years.

Question 10

Cross-sectional data

Answer 10

measurements are made of several
children in each age group, and these are then combined to form a cross-sectional picture of the various age groups in the community at the time of the investigation.

Question 11

Boy vs Girl Growth

Answer 11

Girls grow up faster than boys

– Girls reach 50 percent of their adult height at an earlier age
(1.75 vs. 2.0 years), enter puberty earlier, and cease growing earlier

– Half way through the fetal period, the skeleton is already
three weeks more advanced in girls;

– at birth, the difference is four to six weeks of maturation;

– at puberty, the difference is two years.

Question 12

Mean Growth Takeoff Age

Answer 12

9 ± 1 year in girls

11 ± 1.5 years in boys

Question 13

During the spurt, how much height is gained? (M & F)

Answer 13

• boys gain about 20 cm in height
• while girls gain about 16 cm in height.
• mostly growth of the trunk

Question 14

Peak Height Velocity

Answer 14

*Peak height velocity in boys ~ 13.5 years

*Peak height velocity in girls ~ 11.5 years

The standard deviation for age at the peak height velocity is slightly less then one year.

Question 15

Why do boys end up being taller than girls?

Answer 15

Boys end up being taller than girls because they have two more years of growth before the growth spurt.

During these two extra years of prepubertal growth in boys, the legs are growing relatively faster than the trunk.

– Thus the average male has relatively longer legs than the average female.

• Peak growth rate also a bit higher on average

Question 16

Growth in Weight (M & F)

Answer 16

During the growth spurt, boys may add 20 kg. to their weight, and girls 16 kg

Question 17

Average Height and Weight Graphs
(M & F)

Answer 17

Question 18

Osteoporosis

Answer 18

a condition of the bones where they become thin and brittle due to decreased mineral content, which makes them susceptible to fracture.

Question 19

Needed for Growth (2)

Answer 19

Calcium and Vitamin D

Question 20

Head to Body Ratio in Infants and Adults.

Answer 20

Large head - the ratio of head height to total height equals

• 1:4 in the infant,
• 1:7.5 in the adult.

Question 21

What is Puberty?

Answer 21

refers to the period at which the testes, prostate gland, and seminal vesicles or the breasts, uterus and vagina, suddenly enlarge.

This is the time of the greatest sex differentiation – sexual dimorphism

Question 21

Leg Length to Total Height Ration in Infants and Adults

Answer 21

Lower limbs are much less well developed at birth than upper
limbs - the ratio of leg length to total height equals

• 1:3 in infant,
• 1:2 in adults.

Question 22

Menarche

Answer 22

Menarche refers to the first occurrence of menstruation in females, marking the onset of reproduction
It occurs relatively late in puberty.

• The average age of occurrence in North America is 12.2-13 years
  – There is a standard deviation of plus or minus one year.
• The 95 percent range is 11.0 - 15.0 years.

Question 23

When does Menstruation Begin

Answer 23

Menstruation begins when the height velocity is falling

• The development of mature ova follows
  menarche by as much as two years;
• puberty is not complete in females until sexual maturity has been attained.

Question 24

Radiological (Skeletal) Age (3)

Answer 24

During growth, every bone goes through a series of changes which can be recorded radiographically. The radiological examination allows one to determine how far the skeleton of a child has progressed toward the adult condition. wrist and hand are most commonly used for this purpose because, in this region, there is a large number of centers of ossification.

Question 25

Dental Age (3)

Answer 25

The deciduous dentition erupts from 6 months to 2 years of age and can be used during that period. Permanent dentition provides a measure from 6 to 13 years of age. However, skeletal maturity and dental maturity are not closely related in the individual.

Question 26

Growth Curves

Answer 26

The timing of the peak height velocity and the peak weight velocity are useful maturity indicators.

Question 27

Sexual Age

Answer 27

The secondary sex characteristics can be used as a method of rating maturational development. Ratings can be made of stages in pubic hair development, stages in breast development, and stages of genital development.

Question 28

Chronological vs Biological Age

Answer 28

It is very likely that mental and psychological development are much more closely related with radiological age than with chronological age.

Question 29

Neural Age

Answer 29

In spite of the large size of the central nervous system at birth, much of it is incompletely functional and requires considerable time to develop to the stage at which it can be fully utilized. Girls are ahead of boys throughout the phase of motor and sensory development – * on average, girls learn to – walk earlier – control their bladders earlier – are ahead in the use and understanding of speech. – First in the development of skills needed for fine movements and coordination, such as tying shoes.

Question 30

What Five types of skeletal development have been recognized?

Answer 30

(1) Average children (2) Early maturers - tall in childhood but not as adults (3) Early maturers and genetically tall (4) Late maturers - small in childhood, average as adults (5) Late maturers and genetically short

Question 31

Changes in Body Proportions and Composition

Answer 31

The relationship between one part and another of the growing body is not a consistent one, but changes with age.

Question 32

Shape of the Infant

Answer 32

Large head - ratio of head height to total height equals 1:4 in the infant, 1:7.5 in the adult. Lower limbs are much less well developed at birth than upper limbs - ratio of leg length to total height equals 1:3 in infant, 1:2 in adult.

Question 33

Changes in Shape with Growth

Answer 33

At all ages the dimensions of the head are in advance of those of the trunk, and at all ages more peripheral parts of the limbs are in advance of the more central parts – foot --> calf--> thigh. The bones of the face grow faster than those of the cranial vault - "at adolescence the face emerges from underneath the skull". In the later stages of the adolescent spurt, there is laterality of growth rather than linearity.

Question 34

Indices of Maturity

Answer 34

It is important to be able to assess how far an individual child has progressed toward maturity. The chronological age of a child is an unreliable guide since children mature at very different rates and measurements of height and weight are only partially useful.

Question 35

Factors Influencing Growth and Maturation

Answer 35

A. Genetic Control B. Nutrition C. Secular Trends D. Season and Climate E. Differences Between Races

Question 36

Factors Influencing Growth and Maturation - Genetic Control

Answer 36

- Both genetic and environmental factors influence growth - The progress of any given child is the result of many different factors interacting - Studies of twins have shown that body shape and size, deposition of fat and patterns of growth are all more closely related to nature than to nurture. Heredity affects the end result of growth and the rate of progress toward it.

Question 37

Factors Influencing Growth and Maturation - Nutrition

Answer 37

Malnutrition delays growth. Children subjected to starvation recover almost completely provided the conditions are not too severe Adult size is affected by a less severe level of under-nutrition than adult body proportion (ie) leg length versus trunk length, etc.

Question 38

Factors Influencing Growth and Maturation - Secular Trends

Answer 38

Between 1880 and 1950, the average height of American and European children between 5-7 increased by >0.5 inches per decade (Total 4 Inches) Children are now growing faster and stopping growing earlier. There has been an upward trend in adult height of one cm per decade since 1880. The causes of these trends are probably multiple: better nutrition, lessening of disease, some degree of dominance of height genes?

Question 39

Factors Influencing Growth and Maturation - Season and Climate

Answer 39

Studies done in Europe indicate that season of the year may exert a considerable influence on the velocity of growth. The children grew faster in height in spring and summer than in autumn and winter. Weight gain was faster in the autumn than in the spring.

Question 40

Factors Influencing Growth and Maturation - Differences Between Races

Answer 40

Populations differ slightly in their average adult size, tempo of growth as well as shape. Tempo of growth - Asiatic and African children are ahead of European children in skeletal age, dental maturity and age of menarche. - African American boy is one year ahead in pubertal development compared to the average Caucasian boy. This knowledge may be important to consider when monitoring the growth and development of a child for developmental disorders

Question 41

Nature of Growth

Answer 41

Extremely rapid growth of the brain continues, reaching 90% of its adult weight at 5 years old, whereas body weight is only 25% of adult weight.