Week 3 Pt 1 and Week 2 Pt 2 Flashcards
Describe the sequence of growth in infancy
rapid growth
Describe the sequence of growth in childhood
steady, consistent growth
Describe the sequence of growth in adolescence
A major growth spurt during puberty - can see differences between males and females
Describe the sequence of growth in adulthood
Growth slows down, and body composition changes. Muscle mass may decrease, and many adults gain weight
Describe the sequence of growth with aging beyond adulthood
older adults may lose height and weight due to bone density and muscle mass loss
What is physical anthropology?
provides information and scientific procedures related to the study of biological growth and development
What is anthropometry?
branch of science concerned with biological growth and body measurements
What is the germinal period in prenatal development?
- 0-2 weeks
- conception
- cell division and implantation
What is the embryonic period
- week 2-8
- organogenesis
- foundation for motor skills and cognitive functions
- teratogen exposure may lead to congenital disorders
What is the fetal period
- week 8 - birth
- growth and maturation of organs and tissues
- overall health and viability post-birth
What are the 4 main internal influences to prenatal development?
maternal age, nutrition, maternal stress, and genetic abnormalities
How does maternal age play a role in prenatal development?
- 22-29 generally optimal time to have a baby
- 35+ or <16 - higher risks
- still, most have viable births
How does nutrition play a role in prenatal development?
- 1st trimester most vulnerable, 3rd trimester valuable for brain growth
- well-balanced diet
How does maternal stress play a role in prenatal development?
- can delay motor development
- could also moderate blood flow
What genetic abnormalities play a big role in prenatal development?
down syndrome
What are the 4 main external influences that play a role in prenatal development?
infection and disease, smoking, alcohol, drugs
How can infection and disease impact prenatal development?
- most can be prevented
- syphilis: attacks nervous system
- HIV: cause early death, motor delays
How does smoking play a role in prenatal development?
- affects oxygen regulation
- risk malformed organs, low birth weight, limited physical growth
How does alcohol play a role in prenatal development?
- stays in system for a long time
- fetal alcohol syndrome: delayed/limited motor development
- low birth weight
How do drugs play a role in prenatal development
- stays in system for a long time
- several different effects - most commonly growth restriction
What is low birth weight/pre-maturity and what are the risks
- less than 5lb 8 oz (2.5 kg)
- caused by premature birth or fetal growth restriction condition
- not automatically bad - can catch up
- can have health risks; especially less than 1lb
- motor dysfunction and delay risk
When is the pubescent growth spurt for females? What happens?
- 10-13 years old
- develop breasts, pubic hair
- menarche
When is the pubescent growth spurt for males? What happens?
- 12-15 years old
- pubic and facial hair, voice deepening, growth in reproductive organs
What is involved in hormonal control?
the hypothalamus, pituitary gland, and supporting glands (gonads, thyroid, adrenal)
How is the hypothalamus involved in hormonal control?
the body’s control center
How is the pituitary gland involved in hormonal control
“master gland” - receives signals from hypothalamus to release hormones that trigger growth
How doe the supporting glands play a role in hormonal control?
gonads: ovaries and testes (estrogen and testosterone)
thyroid glands: produces thyroxine, supports growth
adrenal glands: produce androgens, supporting muscle and bone development
What is the hormonal sequence?
hypothalamus → pituiatary gland → groth hormone, thyroid, gonads, or adrenal
What does testosterone do in the body?
- levels increase 10x in puberty for males, 2x in females
- builds muscle
- strengthens bones
- closes growth plates
What does estrogen do in the body?
- increase 10x in puberty for females, 2x in males
- bone development
- tells body to store fat
- closes growth plates earlier than boys
What should we know about growth hormone therapy?
- most children reach 85% of normal adult height with treatment
- typically, 98% of children grow within expected height range
- prescribed typically to children 2-2.5 standard deviations below mean height for age (small for gestational age - SGA)
Describe head and legs size at birth
head: 1/4 of total height; as wide as shoulders and hips
legs: 3/8’s of total height
Describe head and leg size at adulthood
Head: 1/8 of total height; 1/3 of shoulder width
Legs: 1/2 of total height
Why do head and leg size changes matter?
can assess typical brain growth
- first few months - baby’s heads grow quickly, slows down as they get older
- can spot hydrocephalus (fluid build up in brain)
can implicate motor skills and movement
- large head affects ability to balance
What is biacromial breadth?
shoulder width
What is bicristal breadth?
hip width
How do shoulder and hip width change throughout life and during puberty?
- at birth: biacromial = bicristal
- later childhood: small differences between boys and girls
- puberty
→ boys: shoulders are bigger, triangular upper body; throwing, arm movement
→ girls: hips are wider, rounder lower body; balance and stability
What is sitting height to total height like in early childhood?
sitting heigh is 60-70% of total height; trunk larger than legs
What is sitting height to total height like in adolescence?
girls: legs and trunk low ration at 12-13 years old
boys: legs and trunk low ration at 13-15 years old
What is sitting height to total height like in adulthood?
sitting height is 50% of total height
- legs grow faster than trunk
What is a ectomorph physique?
lean, thin
What is a mesomorph physique?
muscularity, balance proportions
What is an endomorph physique?
softer and rounder in contour
A fully developed brain has how many neurons?
100 billion
Nature contributes to ________; environment ____________ connections
pre-wiring; fine-tunes
What is the sequence of events in brain development?
cell proliferation → migration → integration & differentiation → myelination → cell death
In summary, what happens during each event in brain development?
cell proliferation: neurons created rapidly
migration: neurons move where they are needed
integration & differentiation: neurons build connections with other neurons
myelination: neurons get coated with myelin
cell death: neurons get cut, eliminated
What is cell proliferation
- neurons multiply rapidly, and grow in size
- size growth from about 6 months prenatal to first year postnatal
- brain growth spurt in 3rd trimester → 4th year of life
- critical period of neural development
What is migration?
- dendrites grow
- dendrites handle >95% of information flow in system
- thick dendrites develop at ~8th prenatal month; significantly responsible for brain growth from birth to age 2
What happens during integration and diffrentiation?
integration: nerve cells connect and communicate
differentiation: specialization; movements progress from simple and uncoordinated to more precise and controlled
What is synaptogenesis?
- building synapses
- each neuron: ~1,500 to ~15,000 connections
timeline: - at 2 months (postnatal) synaptogenesis in motor cortex
- at 3 months (postnatal) synaptogenesis in visual cortex
What happens in neural development after birth?
- most neuron growth happens in the hippocampus
- neurogenesis is influenced by physical activity
What was shown in the Van Praag (2009) study?
2.5 times more neurons growth in running condition than non-exercise condition mice
When does myelination start?
starts in 2nd trimester, continues well into adulthood
What are the key pathways and timing with myelination?
motor roots develop first, then sensory roots
What are the key milestones to know of when pathways become myelinated?
- visual pathways at birth to about 5 months (postnatal)
- touch develops until 2 years old
- motor control develops until 4-5 months (postnatal)
- higher brain functions (3 months postnatal to age 10)
- memory - develops well into the 30s
How is myelination linked to neurogenic behaviours?
- 3-4th prenatal month
- caused by neural connection to muscle
ex. fetus kicking, stretching its arms
How are reflexes linked to myelination?
- 8th prenatal month
- caused connection of sensory input and motor response
e.x grasping
How is voluntary motor control linked to myelination?
- after birth
- motor pathways are myelinated
e.x. reaching and grabbing, rolling over
What is pruning and cell death?
- cells begin pruning around 10 years old
- during first ten years of life - brain is actively using energy (glucose)
- reduces glucose use after age 10
- “use it or lose it”
- brain may lose as much as 40-75% of neurons they originally made
- neurons compete with one another
What are the windows of opportunity?
- exuberant connectivity
- windows stay open for a short time
- gross motor skills (e.g. walking, running, jumping): develop from prenatal stages to ~age 5
- fine motor skills: continues to improve until around age 9
- unused connections fade away at around age 10
Describe brain size at age 3 and 6
- by age 3, the brain is nearly 90% of its adult size
- by age 6, it has reached it full size
What is the brain growth sequence?
- midbrain: develops first, reflexes and automatic processes
- cerebrum: h
- holds cerebral cortex, basal ganglia, hippocampus and more
- complex thinking and functions - Cerebellum:
- coordination, balance
- maturity around age 4
When does the plasticity happen?
- during normal development
- learning a new skill
- after injury, healthy parts of the brain can take over functions from damaged areas (hemispherectomy, stroke)
What is the corpus callosum?
- share information between hemispheres
- physically grows until ~age 5
- functions keep developing until ~age 10
What happens to the brain and neurons during advanced aging?
- neuron loss → lose 5-30% neurons, shrinks and loses 7% of its weight
- reduced connectivity → dendrites shrink, axons lose density, psychomotor slowing
- decline in balance
→ cerebellum loses ~40% of cells by age - slower nerve signals
