PHYSIOLOGY: study of function
HUMAN : focus on humans but also other organisms (e.g. laboratory animals) as well as isolated organs, tissues, cells
DEVELOPMENT: comprises functional changes with age, starts at fertilization, ends with death, may be divided into prenatal and postnatal periods, does follow a well established timetable thereby allowing for preventive/ therapeutic interventions
GROWTH: Quantitative increase in size or body mass resulting from an increase in structurally and functionally complete units.
DEVELOPMENT: Progression of changes leading from an undifferentiated state to a differentiated (highly organized, functionally specialized) state
Epigenesis: developmernt of new characters in an initially un-differentiated (or little differentiated) entity
ONTOGENY RECAPITULATES PHYLOGENY
ONTOGENY: changes during developmental stages approximate the "telescoped", sequential view of changes during
PHYLOGENY: history of species/phylum
DEVELOPMENT does not proceed in a uniform (even) timetable but rather Undergoes "Critical Periods"of "Accelerated Development" separated by periods of slower development
Critical periods are most susceptible to environmental influences hencethey offer windows of opportunity to prevent/treat disorders produced by damaging environmental influences acting during critical periods, to optimize development by enhancing beneficial influences
"Optimal development" leads to optimal adulthood and old age
SOME CHARACTERISTICS OF GROWTH & DEVELOPMENT
Growth and development are processes continuing throughout the lifespan
Growth and development are processes that follow a precise timetable: each change is dependent on what preceded it and, in turn, will affect what will come after
Therefore, events during early life will influence function during maturity as well as length of lifespan and quality of life in old age
While the sequence of growth & developmental events has the same timetable for all individuals of the same species, there is a great individual heterogeneity in the timing and magnitude of these events
Growth & development depend on both genetic and environmental factors (the so-called nature and nurture)
The term plasticity refers the capacity of the organism to be modified i.e. to be improved or damaged
Plasticity is operative throughout life but it is greatest during the so-called critical periods
Critical periods are those periods in which growth and/or development are the fastest, & the organism is most susceptible to the beneficial or damaging effects of the environment
Hence , interventions for optimizing or for protectingnormal function are most effective during critical periods
Divisions of lifespan and Age periods of life before maturity. *Please see Table 1 and Table 2 in the Reader (pp. 2 and 4).
Major Current Biomedical Advances Include
Decreased human neonatal mortality, Worldwide extended human longevity, Antibiotics, Human genome project, Improvement of Public Health conditions (eg. nutrition, environmental factors), New Biotechnologies (eg. organ/tissue/cell transplants, home test kits for physiologic/ pathologic conditions, amplification of DNA for sequencing, cloning) Others?
HISTORICAL NOTE: In the XVIth century, Girolamo Cardano (1501-1576), practicing physician, mathematician, astologer, and encyclopedist wrote: "The studious man should always have at hand a clock and a mirror: a clock...to keep track of time, a mirror...to observe the changing condition of his body.