Lifespan Development Flashcards
Describe the major events of prenatal development
1st Trimester - Major organ systems = laid down (3 tissue layers - ectoderm/mesoderm/endoderm)
2nd Trimester - Development of organs + systems
- Changes in body shape and proportions
3rd Trimester - Rapid foetal growth
- Major organ systems = fully functional
- Deposition of adipose tissue
(fully formed by 38 weeks - just laying down fat)
Major organ development (start and critical period)
*Critical period is when most vulnerable to birth defects created by harmful agents
- Placenta - Begins week 1
- Brain + Spinal cord - Begins week 2
- Critical period = 2-20 weeks - Heart + Foetal Circulation - Begins week 3
- Critical period = 3-9 weeks - Lungs - Begins week 4
- Critical period 4-17 weeks
Foetal circulation adaptations before birth
- Umbilical vein - connects placenta to liver and ductus venosus
- Ductus Venosus - connects umbilical vein to inferior vena cava
- Hypoxic pulmonary vasoconstriction - Alveoli are filled with fluid = arterioles constrict creating higher pressure in pulmonary artery/right ventricle/right atrium
- Forman Ovale - hole between atriums
- Ductus arteriosus - connects pulmonary artery to aorta
(4&5 allow blood to skip wasted trip of lungs due to high pressure) - Umbilical artery - takes blood from internal iliac arteries back to placenta (has a low pressure to create gradient and attract blood)
What happens after the baby’s first breath?
- Alveoli fill with air - pressure decreases
- Blood then rushes to lungs - bypassing ductus arteriosus (then constricts)
- Pressure in left atrium rises - higher than right atrium - foramen ovale closes
- Umbilical cord is clamped - no blood supply - Umbilical vein and artery constrict
- Ductus venosus stays open for few hours but eventually closes due to lack of blood.
Respiratory System in infancy (birth - 2 years)
WoB = higher due to:
- Rib cage = soft and cartilaginous (firms @ 3 years)
- Intercostals are weak (less type 1) + poorly developed
- Diaphragm = flatter (more horizonal insertion)
- Fewer alveoli and less airways connecting each one
- Airways = less cartilaginous support - prone to collapse
- Nasal breathing
- Higher Metabolic rate - require more o2
Musculoskeletal system in infancy (birth - 2 years)
Bones
- 300 bones that will fuse to form 206
- soft and cartilaginous - will ossify over time
Muscles
- Fibres are small and water - weak and fatigue easily
Fat
- Laid down until 9 months old (muscular system is fat orientated for early stages)
Neurlogical system in infancy (birth - 2 years)
Brain
- 1/4 of total body weight (floppy head)
- Lower Centres = most developed (incl. brainstem and medulla - involuntary control of heart/breathing)
Nerves
- All Present - but need ‘transient exuberance’ = process of learning the correct pathways
- Primitive reflexes e.g grasp/locate breast
- Flexural tone - Extension is difficult ‘foetal position’
In first year
- Physical growth
- Factors that affect growth/development
- 1/3 adult height at birth
- growth will then occur in 3 phases
- weight will be put on before height
- different parts grow at different rates
- first 6 months = 2lbs per month
- second 6 = 1lb per month
- @ 1 year: boys ~ 10kg / girls ~ 9.5kg - Genetics (sex/race/physical status)
Environment (culture/nutrition/climate)
Delivery (complications/multiple births)
State of mother (physical and mental health)
Development in childhood (2-10 years)
- Steady physical growth
- Refinement of Motor skills
Development in adolescence (10-20 years)
Puberty: boys @ 12-16 years - enlargement of testes and penis - hair growth - axilla/pubic region/face - Increased muscle mass - Voice deepens girls @ 10-14 years - Breast development - hair growth - axilla/pubic region - menstruation
After puberty - background levels of hormones maintain differences between sexes
Physical maturity = when growth stops ~ 18-21 years
Mental and emotional maturity - has no set age
Musculoskeletal developments in adolescence
Bones - accelerated bone deposition - skeleton grows
- epiphyseal plates will close
Muscles - increased strength and endurance (testosterone allows more growth so boys will often be larger)
Neurological and Cardiorespiratory development in adolescence
Neurological
- Sex hormones affect the CNS
- Increased sex drive
Cardiorespiratory
- Testosterone causes blood volume to increase
- Testosterone causes growth of larynx and thickening of vocal cords - deepening voice.
Early Adulthood Development (20-40 years)
- Intellectual/Social/Emotional development
- Most physically capable
- No real regeneration but equally very little degeneration
Middle Aged Development (40-65 years)
- Generally good health and physical function
- Menopause
- Gradual signs of degeneration
Older Age development (65+ years)
- Retirement
