3. Growth and Development Flashcards
What is Growth?
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.
Neonatal Period
extends from birth to the end of four weeks
Infancy
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.
Childhood
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.
Adolescence
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
Adulthood
the period of life beyond adolescence. An adult has reached maximum physical stature as determined by genetic, nutritional, and environmental factors.
Distance curve
measurements taken at intervals are plotted against time to produce a graph of progress.
Velocity curve
increments in growth are plotted against time to show the variation in the rate of growth with time.
Longitudinal data
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.
Cross-sectional data
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.
Boy vs Girl Growth
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.
Mean Growth Takeoff Age
9 ± 1 year in girls
11 ± 1.5 years in boys
During the spurt, how much height is gained? (M & F)
- boys gain about 20 cm in height
- while girls gain about 16 cm in height.
- mostly growth of the trunk
Peak Height Velocity
*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.
Why do boys end up being taller than girls?
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
Growth in Weight (M & F)
During the growth spurt, boys may add 20 kg. to their weight, and girls 16 kg
Average Height and Weight Graphs
(M & F)
Osteoporosis
a condition of the bones where they become thin and brittle due to decreased mineral content, which makes them susceptible to fracture.
Head to Body Ratio in Infants and Adults.
Large head - the ratio of head height to total height equals
- 1:4 in the infant,
- 1:7.5 in the adult.
What is Puberty?
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
Leg Length to Total Height Ration in Infants and Adults
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.
When does Menstruation Begin
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.
Radiological (Skeletal) Age (3)
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.
Dental Age (3)
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.
Growth Curves
The timing of the peak height velocity and the peak weight
velocity are useful maturity indicators.
Sexual Age
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.
Nature of Growth
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.
