Lifespan Motor Development Exam Two

universality

patterns that hold for all humans

variability

individual variation

prenatal development

early development is controlled by genes

the embryo or fetus is sensitive to extrinsic factors

• positive effects (proper nutrients, exercise, general health of mother)

• negative effects (abnormal external pressure to abdomen, viruses or drugs in bloodstream)

embryonic development

• conception to 8 weeks

• differentiation of cells to form specific tissues and organs

• limbs formed at 4 weeks; heartbeat begins

• human forms noticeable at 8 weeks

growth of organs and tissues occur by

• hyperplasia: increase in cell number

• hypertrophy: increase in cell size

cells have:

• plasticity

  • modifiability; malleability

  • tissues can assume functions of other tissues

growth tends to proceed in two directions:

• cephalocaudal

• proximodistal

cephalocaudal

• head to toe

• head and facial structures grow fastest

proximodistal

• near to far

• growth proceeds from the body toward the extremities

fetal nourishment

• characteristics of fetal environment can positively or negatively affect growth

• oxygen and nutrients diffuse between fetal and maternal blood in the placenta

poor maternal health status can affect the fetus

• better conditions: adequate, safe food supply; protective, clean environment; good prenatal care

• worse conditions: lower SES = low birth weight

  • low birth weight - greater risk for disease, infection, and death in the weeks after birth

genetic congenital effects

• inherited abnormalities

• new mutation

  • alteration or deletion of a gene during formation of egg or sperm cell

extrinsic congenital effects

fetal nourishment comes from the carrier

• can be good … or bad

external causes of abnormal development

• nourishment

• physical environment

teratogens

• any drug or chemical that causes abnormal prenatal development upon exposure

• effects to teratogens depend on when the fetus was exposed and how much of the substance

• typically, the earlier the exposure/infection, the more serious the abnormalities

physical environment

• external or internal pressure on the infant

• x-ray exposure

• environmental pollutants

• extreme internal environmental temperature

• changes in atmospheric pressure

environmental effects can result in

• delayed growth

• malformation

• life-threatening conditions

effects of these factors also depends on fetus’ stage of development

prenatal development: summary and synthesis

1. physical growth and development begins in utero

2. prenatal development is influenced by genetic and extrinsic factors

3. individuals are, in part, products of the factors that affected their prenatal growth and development

growth and aging change individual constraints

• genetic and extrinsic factor combine to influence growth and aging

• we observe patterns in growth and aging

• educators and therapists can make tasks developmentally appropriate

growth patterns are

predictable and consistent, but not linear

• have rapid changes at some points; plateau at others

sigmoid curve

compare individual growth with the average and adjust expectations

• height follows pattern

girls peak height velocity occurs at

11.5 to 12 years old

• ends at 14 to 16 years old

boys peak height velocity occurs at

13.5 to 14 years old

• ends at 17 to 18 years old

long growth period

weight

• follows a sigmoid pattern

• highly susceptible to extrinsic factors

  • diet, exercise

peak weight velocity follows peak height velocity

• 2.5 - 5 months in boys

• 3.5 - 10.5 months in girls

extent of growth

• distance curve

• measurement of growth plotted against age

• can determine variables of growth at certain ages

rate of growth

• velocity curve

• distance/time

• can determine peak growth velocity

  • age at which growth is fastest for a portion of the lifespan

peak height velocity (PHV)

• the age at which one is growing the fastest

• age at takeoff = age at which one changes from slow growth to rapid growth

girls PHV

11.5 to 12 years old

boys PHV

13.5 to 14 years old

relative growth

• the body as a whole follows a sigmoid pattern BUT specific parts, tissues, and organs have different growth rates

• body proportions change from heavy-headed, short-legged form at birth to adult proportions

physiological maturation

• developmental process of leading to a state of full function

• as we grow in size and increase in years

  • early vs. late maturers

• it is difficult to infer maturity from age alone, size alone, or even age and size together

secondary sex characteristics

aspects of form of structure appropriate to males or females, often used to asses physiological maturity in adolescence

• appear at a younger age in girls and boys who are early maturers

girls secondary sex characteristics

• mature at a faster rate than boys; enter adolescent growth spurt sooner and characteristics appear sooner

• menarche occurs

• menarche typically follows PHV by 11-12 months

boys secondary sex characteristics

• mature at a slower rate than girls

• no landmark comparable with girls’ menarche; production of viable sperm is gradual

maturation status - a constraint

• individuals who are more mature are likely stronger and more coordinated (despite being the same chronological age)

• typically, we group youth sport teams according to age, not maturation status

• temporary effects, ~ 6 months

extrinsic influence on postnatal growth

• during periods of rapid growth (just after birth and early adolescence), growth is sensitive to alternation by environmental factors

• early diet - breastfed infants vs. formula fed

• catch-up growth

catch-up growth

rapid physical growth of the body to recover some or all potential growth lost during a period of negative extrinsic influence

adulthood and aging

• height is stable in adulthood but may decrease in older adulthood

• the average adult starts gaining weight in the 20s

skeletal system

an individual’s “structure”

muscular system

allows an individual’s movement

adipose system

energy storage, insulation, and protection (i.e., fat)

endocrine system

exerts control over certain cellular functions using hormones

nervous systems

controls movement, cognition, and speech

skeletal system early development

• embryo has a cartilage model of the skeleton

  • initially, structure is maintained via cartilage

  • ossification centers

• at 2 months gestational age, ossification begins at primary center

• primary ossification center

• shafts of long bones are ossified by time of birth

ossification centers

cartilage model sites where bone is deposited

primary ossification centers

area in the midportion of the shafts of long bones where bone cells are formed

• cartilage-model bones of the fetal skeleton begin ossifying, from the center outward, to form bone shafts

skeletal system (postnatal development)

• secondary ossification centers

• these centers are called epiphyseal plates, growth plates, or pressure epiphyses

• appositional growth

secondary ossification centers

sites where bone growth occurs following primary growth

• typically, at the ends of bones and lead to an increase in length

skeletal system (growth cessation)

• growth at the epiphyseal plates stops at different times for different bones

• closure occurs at different rate for different populations

  • all bones are typically closed by age 15 for females and age 18 for males

appositional growth

increase in bone girth

osteoporosis leads to

rib cage collapse, stooped posture, and reduced height

hormone

older women past menopause are at the highest risk for developing osteoporosis of all groups

exercise/activity

exercising, like weight-lifting or jumping, can reverse age-related bone loss in older men

achondroplasia

• a disorder of bone growth that prevents changing of cartilage to bone

• most common form of disproportionate dwarfism

• atypical and delayed patterns of motor development

common structural and functional differences, from typical bodies

• shorter fingers

• shorter statues

• enlarged head and forehead

• limited range of motion at elbows

• atypical spine structure (e.g., lordosis of spine: lordotic curve arches too far inward)

• different body proportions (shorter limbs/longer trunk/larger head)

prenatal growth invovles

hyperplasia and hypertrophy

postnatal growth mainly involves

hypertrophy

myofibrils

basic unit of muscle cells

sarcomeres

basic unit of striated muscle tissue

muscle increase in diameter and length by the addition of

• myofibrils

• sarcomeres

smooth muscle type

involuntary, non-striated muscle

• in organs: stomach, intestines, bladder, uterus, skin, etc.

cardiac muscle type

involuntary, striated muscle

• in the heart

skeletal muscle type

voluntary, striated muscle

• the muscles you “think” of when you hear muscles, attached to bones by tendons

slow twitch fibers (Type I)

good for endurance activities

fast twitch fibers (Type IIa, IIx)

intense short-duration activities

differentiation of muscle fiber type

• at birth, 15% of fibers are undifferentiated

• by age 1, distribution of muscle fiber type is similar to adult distributions

• exact proportions vary between individuals

muscular system in adults

• minimal muscle loss through adulthood until 50 years of age (~10%)

• by 80 years, an average of 30% of muscle mass is lost

why does as the heart age is loses it ability to adapt to increased workloads

may be due to degeneration of heart muscle, decreased elasticity, changes in fibers of the vavles, or (partly) lifestyle

Heart rate variability (HRV) indicates cardiac health

• variation in the time interval between consecutive heartbeats in milliseconds

• higher HRV > indicative of lower cardiac risk and better outcomes (lower morbidity, mortality, improved psychological well-being)

assessed older adults for indices of HRV and physical activity

0ms are unhealthy, 50-100 have compromised health, >100 are healthy

internal/visceral fat

internal fat around the viscera

subcutaneous fat

fat under the skin

adipose tissue at birth

only accounts for 1.1 pounds of body weight

adipose tissue in adolescence and puberty

females increase fat more dramatically than males do

early fat/diet that’s relevant

• greater than average peak weight velocities are associated with increased risk of overweight and obesity at age 4

• if overweight at age 8, there’s a higher risk of becoming an overweight adult

fat distribution throughout childhood

• young infants with higher weight and subcutaneous fat levels had an increased risk of motor delay

  • overweight infants were 1.8 times more likely to exhibit a motor delay, than infants with typical weight

fat distribution acorss childhood

• subcutaneous fat increases from age 6 or 7 years until age 12 or 13 in males and females

• subcutaneous fat then continues to increase in females, and change rate of increase for males

adipose tissue in adulthood

• re-distribution in body fat

• both men and women tend to gain fat during adulthood, not inevitable

re-distribution in body fat

• subcutaneous fat on the limbs tend to decrease, while visceral/internal fat tends to increase

• higher visceral fat → at risk for disease

intrinsic fat gain

changes in injury, health condition

extrinsic fat gain

nutrition/diet activity

endocrine system

• plays role in regulating growth through hormones

• excess or deficiency of hormones can alter growth

hormone

a chemical substance used to control or regulate body functions secreted by a glad

growth hormone

• secreted by anterior pituitary

• necessary for normal growth

  • stimulates protein anabolism

• deficiency can result in growth abnormality

  • cessation of linear growth

thyroid hormones

• secreted by thyroid gland

  • regulation of metabolism

  • T3 and T4 (influence whole body growth after birth)

  • pituitary gland stimulates TSH

• thyroid function declines with aging

thyroid hormone disorders

• hyperthyroidism

• hypothyroidism

hyperthyroidism

increases levels of thyroid hormone

hypothyroidism

insufficiency of thyroid hormone

gonadal hormone

• secreted by gonads

  • influence on growth, sexual maturation

• androgens

  • secreted by testes, adrenal glands

  • promote growth of muscle mass

• estorgen

  • secreted by ovaries, adrenal cortex

  • promoted accumulation of fat

insulin

• produced in the pancreas

  • vital for carbohydrate metabolism

  • necessary for full functioning of growth hormone

• especially important during growth

  • deficiency can decrease protein synthesis

type 1 diabetes

results from the pancreas’s failure to produce enough insulin due to loss of beta cells

type 2 diabetes

begins with insulin resistance, a condition in which cells fail to respond to insulin properly

gestational diabetes

pregnant women without a prior history of diabetes develop high blood sugan levels

endocrine system in older adults

• imbalances may develop between nervous, endocrine, and immune systems

  • may result in increased risk of disease

• thyroid disorders are quite prevalent

  • long term increase → related to congestive heart failure

  • insufficiency → acceleration of aging systems

• decreasing gonadal hormone levels are associated with loss of bone and muscle tissue

nervous system

• most neurological development occurs very early in the life span

  • genes → director of nervous system development

  • extrinsic factors exert influence

neurons

cells of the nervous system that receive and transmit information

synapse

connection between 2 neurons

• connection is made by the release of neurotransmitters from an axon

myelin

lipid-rich substance that surrounds the axon of some nerve cells, forming an electrically insulting layer