Motor Learning Exam 3 contents

CH8

What two factors combine to influence growth and aging?

Genetic factors and environmental (extrinsic) factors.

What are normative trends?

Patterns of growth and aging that generally hold true for all humans.

What is individual variation?

Differences between individuals in the patterns and timing of growth and development.

Why should educators and therapists understand growth patterns?

To make tasks and activities developmentally appropriate.

What does G × E represent?

Gene-environment interaction.

What primarily controls early prenatal development?

Genetic factors.

How can extrinsic factors affect prenatal development?

They can positively or negatively influence the embryo or fetus.

What are examples of positive prenatal environmental influences?

Exercise, healthy eating, appropriate weight gain, and hydration.

What are examples of negative prenatal environmental influences?

Alcohol, drugs, too many or too few calories, dehydration, and extreme temperatures.

What is cell differentiation?

The process by which cells develop into specific tissues and organs.

At approximately what week are limbs formed?

Week 4 of embryonic development.

When does the recognizable human form become noticeable?

Around 8 weeks.

What are the two processes involved in fetal growth?

Hyperplasia (increasing cell number) and hypertrophy (increasing cell size).

What is the cephalocaudal growth pattern?

Development proceeds from the head toward the feet.

What is the proximodistal growth pattern?

Development proceeds from the center of the body outward.

What is plasticity?

The capability of taking on a new function.

Where do oxygen and nutrients pass between maternal and fetal blood?

The placenta.

What is the Barker Hypothesis?

Poor maternal health and prenatal conditions can influence the fetus's later health and metabolism.

What are congenital defects?

Abnormalities that are present at birth.

What can cause abnormal prenatal development?

Genetic factors, environmental factors, or interactions between the two.

What is a dominant genetic disorder?

A disorder caused by a defective gene inherited from one parent.

What is a recessive genetic disorder?

A disorder requiring a defective gene from each parent.

How can gene mutations affect development?

They can alter normal growth and maturation.

What causes Down syndrome?

An extra chromosome 21.

What are characteristics associated with Down syndrome?

Intellectual disability, distinctive facial features, visual and hearing impairments, and heart defects.

What are teratogens?

Agents that can cause malformations or abnormal development in an embryo or fetus.

How can teratogens reach the fetus?

Through the maternal nourishment system and placenta.

Does the placenta block every harmful substance?

No. It blocks some substances but does not prevent all harmful substances from reaching the fetus.

Can too much or too little of a substance cause teratogenic effects?

Yes. Both excessive and insufficient amounts can cause developmental problems.

Which fetal tissues are most vulnerable to teratogens?

Tissues undergoing rapid development at the time of exposure.

What environmental factors can negatively affect prenatal development?

Pressure, temperature extremes, X-rays, gamma rays, oxygen-deficient atmospheres, and pollutants.

What nutrient is especially important for neural tube development?

Folic acid.

What growth pattern does overall postnatal growth follow?

A sigmoid (S-shaped) pattern.

Do all individuals experience growth spurts at the same time?

No. Timing varies between individuals and between sexes.

What growth pattern does height follow?

A sigmoid (S-shaped) pattern.

At what age do girls typically reach peak height velocity?

Approximately 11.5–12 years.

When does girls' height growth taper off and end?

Tapers around age 14 and generally ends around age 16.

At what age do boys typically reach peak height velocity?

Approximately 13.5–14 years.

When does boys' height growth taper off and end?

Tapers around age 17 and generally ends around age 18.

Why are males typically taller than females?

Males generally have a longer period of height growth.

What is peak height velocity (PHV)?

The age at which an individual experiences their fastest rate of height growth.

What factors particularly influence weight growth?

Extrinsic factors, especially diet and exercise.

When does peak weight velocity occur relative to PHV in boys?

Approximately 2.5–5 months after peak height velocity.

When does peak weight velocity occur relative to PHV in girls?

Approximately 3.5–10.5 months after peak height velocity.

What does "grow up, then fill out" mean?

Peak weight velocity generally follows peak height velocity.

Do all body parts and organs grow at the same rate?

No. Individual tissues and organs have different growth rates.

How do body proportions change from birth to adulthood?

From a head-heavy, short-legged form toward adult body proportions.

What body proportion change is particularly noticeable in adolescent boys?

An increase in shoulder breadth.

Why can't maturity be determined from chronological age alone?

Individuals mature at different rates.

What are five methods used to assess physiological maturation?

Dental eruption, secondary sex characteristics, skeletal age, height/weight percentiles, and age at peak height velocity.

What is canalization?

The tendency to follow a particular growth percentile or developmental pathway.

What is another name for canalization?

Homeorrhesis.

What is the concept behind canalization?

Target-seeking growth that is genetically controlled when the environment does not restrict normal growth.

At approximately what age does height become more stable for assessing canalization?

Around age 3.

What does age at PHV indicate?

Somatic maturation, or the timing of physical growth and maturation.

When do secondary sex characteristics appear?

As a function of maturation; earlier in early maturers.

What are the five stages of secondary sex characteristics based on?

Breast, pubic hair, and genitalia development.

What is catch-up growth?

Accelerated growth after an earlier environmental restriction is removed.

What happens to height during adulthood and older adulthood?

Height is relatively stable in adulthood but may decrease during older adulthood.

What contributes to height loss in older adults?

Compression of cartilage pads and osteoporosis.

What commonly happens to adult weight beginning in the 20s?

Adults tend to gain weight, influenced by diet, exercise, and loss of muscle mass.

What do distance curves show?

The extent or amount of growth over time.

What do velocity curves show?

The rate of growth over time.

What do peaks on velocity curves indicate?

Ages at which the rate of growth changes from faster to slower.

What are two invasive prenatal assessment methods?

Amniocentesis and chorionic villus sampling.

What is the most common noninvasive prenatal assessment method?

Ultrasound.

What other imaging method can assess prenatal development?

3-D imaging using newer imaging software.

CH9

What are the five major body systems discussed as structural constraints?

Skeletal, muscular, adipose, neurological, and endocrine systems.

What is a developmental rate limiter?

A body system that lags in development and restricts overall performance or development.

What influences the development of body systems?

Extrinsic factors.

Why is it important to understand average developmental patterns and individual variation?

To recognize typical changes while accounting for individual differences.

What is the prenatal skeletal system initially modeled from?

Cartilage.

Where does ossification begin in long bones?

At primary ossification centers in the middle portion (diaphysis or midshaft).

Where does bone length growth occur after birth?

At secondary ossification centers at the ends of bones.

What are epiphyseal plates?

Growth plates at the ends of bones where longitudinal bone growth occurs.

What are other names for epiphyseal plates?

Growth plates or pressure epiphyses.

What is appositional growth?

An increase in bone girth or thickness.

What are traction epiphyses?

Sites where muscle tendons attach to bones.

Do traction epiphyses contribute to bone length?

No.

When do most epiphyseal plates close?

Typically by ages 18–19, although timing varies between bones.

Which sex typically experiences earlier epiphyseal plate closure?

Girls.

What does earlier epiphyseal plate closure in girls reflect?

Earlier average maturation.

What happens to bone throughout the lifespan?

Bone undergoes remodeling: old bone is absorbed and new bone is formed.

Why does bone become more brittle with aging?

Bone formation may fail to keep pace with bone reabsorption.

What happens to skeletal structure in adulthood without osteoporosis?

The structure itself changes relatively little.

What is osteoporosis?

A condition involving loss of bone mass and strength.

What structural changes can osteoporosis cause?

Rib cage collapse, stooped posture, and reduced height.

What factors influence the extent of bone loss?

Hormone levels, diet, and exercise.

What are the two processes involved in prenatal muscle growth?

Hyperplasia (increasing cell number) and hypertrophy (increasing cell size).

What primarily contributes to postnatal muscle growth?

Hypertrophy.

What growth pattern does muscle follow?

A sigmoid pattern.

How do muscles increase in diameter and length?

Through the addition of sarcomeres.

When do sex differences in muscular development become marked?

During adolescence, especially in upper-body musculature.

What are the three adult muscle fiber types?

Type I, type IIa, and type IIb.

What percentage of muscle fibers are undifferentiated at birth?

Approximately 15–20%.

By what age is muscle fiber-type distribution similar to adults?

Approximately 1 year.

Do all individuals have identical muscle fiber-type proportions?

No. Exact proportions vary between individuals.

When does significant age-related muscle mass loss generally begin?

Loss is minimal until approximately age 50.