Module 1- G&D

growth

-change in physical dimension

-involves a quantitative increase in physical dimensions

-includes cellular and extra-cellular components

-occurs in 3 ways: cell proliferation, cell hypertrophy, and increase in amount of ECM

development

-progression of changes, either quantitative or qualitative

-leads to increase in skill, capacity, and complexity of function, or change in relative position of a part of body as a result of differential growth

-related to growth, but not synonymous

growth periods & approximate age

measures used to assess development

-chronological assessment

-biological/physical assessment

-cognitive assessment

-psychosocial development

types of studies

-cross section study: mean and SD of a population, establishment of norms and standards

-longitudinal study: individual difference, rate of growth, timing of a growth event

-mixed longitudinal study: twin study, study of genetic-environment interaction

types of growth curves (distance and velocity)

-distance curves: height attained in cm at successive ages, somatic distance curve is S-shaped

-velocity curves: increment in stature from one stage to the next, adolescent growth spurt (i.e. rates of growth)

growth curves for different types of tissues

-brain/head grow faster than the rest of the body

-reproductive growth is slow and then sharp increase during puberty

-lymphoid tissues relatively fast and then shoots over 100% size and then decreases to 100% in adult

-reproductive tissue mature before brain/head and other body tissues in rats but NOT in humans

-general somatic curve: height, weight, skeleton, muscles

-reproductive curve: slow in pre-pubertal phase, rapid in adolescence

-neural curve: brain, skull, eyes, ears; development earlier than any other tissues or organs; NO adolescent spurt

-lymphoid curve: tonsils, adenoids, appendix, intestines, spleen; pre-adolescent maximum, followed by regression to adult value

cranial and facial growth curve

-all cranial dimensions are more advanced than the facial dimensions except cranial base dimension in early age

maxillary and mandibular growth curves

-facial growth curve runs between the neural (cranial) and general somatic curves

-maxillary growth curve more closely related to the neural growth curve (bc it’s closer to cranial base)

-mandibular growth curve more closely related to general somatic curve

-considerable adolescent spurt, particularly in the mandible

growth velocity curve at fetal period

-peak velocity for both stature and weight of all periods

-rapid growth in length at 2nd trimester

-rapid growth in weight at 3rd trimester

growth velocity curve at post-natal period

-growth rate declines dramatically after birth until adolescent period

-second spurt occurs at adolescent period

-in case of twins, due to space limitation of the maternal environment, growth rate may increase after birth with the peak weight velocity occurring at 2 months post-natal

growth velocity curve at adolescent period

-growth rate increase again for 2-3 years then declines toward adult period

-pubertal growth spurt caused by additive effects of sex hormone production

changes that occur in cranial dimensions during pre- and postnatal growth periods

-size change

-timing

-profile proportional changes

-differential growth of head and body

cranial dimension size changes during pre- and postnatal growth periods

-small changes in cranial width (A) and interorbital width (B) between newborn and adult

-large changes in facial width (bizygomatic width) and upper facial height (C) between newborn and adult

-newborn much wider than visceral cranium (splanchnocranium); in adult these plans are much closer because of increase in size of zygomatic bone

cranial dimension timing changes during pre- and postnatal growth periods

-from 6 to adulthood: facial volume increases by more than 40%

-facial volume of males larger than that of females at all ages EXCEPT in the 11-12 year old group

-at age of 14-15, female facial growth almost completed; males will continue facial growth for a few more years

profile proportional changes during pre- and postnatal growth periods

-in newborn profile, proportion between forehead and face is 1:1

-in adult profile, proportion changes to 1:2

-substantial increase of facial region

-differential growth between neurocranium and splanchnocranium meaning that the face develops later than the skull

differential growth of head and body during pre- and postnatal growth periods

-at early stages, head is a large percentage of the body but after the 3rd month of prenatal life the proportion of total body size contributed by the head and face steadily declines

-at all ages, head is in advance of trunk

-growth gradient of the body is rostro-caudal or cranio-caudal

-at all ages, foot is closer to adult status than the leg

-leg is closer to adult status than thigh

-growth gradient of extremities is disto-proximal

morphogenesis

-process by which cells, tissues, and organs become arranged in a specific pattern with definite relations to one another in size and shape

-process which determines form and pattern

critical periods

-time of greatest sensitivity of a tissue, organ, or system to a specific insult

-important in understanding effects of teratogens on developing embryo and fetus

catch-up growth

-accelerated growth that occurs in children when normal food intake is resumed following deprivation of adequate nutrition that has resulted in reduced height and weight growth

-often experienced by children following major illness

-more pronounced in females than males