Week 4 Flashcards
What happens with heart growth?
heart grows rapidly
- begins in 3rd prenatal week
- 4-5 prenatal months: can hear heartbeat
- 2x weight in 1st year
- 6x weight by 9 years
- big growth spurt from 9-16 years
heart grows in proportion to heart blood volume
What are the sex differences with hearth growth?
- relatively same until puberty
- at puberty, male heart 15% larger than female
What happens with lung growth during prenatal development?
- early development: lungs buds form around the 3rd-4th week
- bronchial completed by the 16th fetal week
- sensory/motor nerves present by 15 weeks
- capillaries form at 20 weeks; an alveoli form at far branches
- alveolar-capillary interface: essential for gas exchange, begins development around the 6th fetal month
What happens with lung growth during postnatal development?
- birth: 20 million alveoli present
- rapid growth after birth
- year 1: 3x lung capacity
- year 8: 300 million alveoli (same as adult)
- after age 8: alveoli grow bigger, chest wall grows to maturity
How does aerobic power change throughout lifetime?
- VO2 max increases through childhood
- sex differences start around 12 years old:
→ continues for males until age 18
→ continues for females at age 14 - declines steadily after: 5-20 increase with training
Describe aerobic power differences
- 70% of individual differences in VO2 max are explained by body mass
- females 15-30% lower VO2 max than males
- heritability of VO2 max is over 90%
- how well this gene is expressed is dependent on active lifestyle
How does anaerobic power change with growth?
increases progressively with growth
Describe anaerobic power differences
anaerobic power increases over time as glycolytic capacity and acidosis maximum increases; females less power than males
How does heart rate change with age and gender?
- decreases with age
- females ~5 beats/min higher than males
How does cardiac output change with age and gender?
- increases with age (+ heart volume & + maximal cardiac output)
- males generally higher than females
How do vital capacity and pulmonary ventilation change with age and gender?
growth:
- increases with age
- linked with body size
sex differences:
- males and females increase at same rate until puberty
- males have larger values after puberty
Children create ____ heat, and tolerate it ______ than adults
more; less
How does thermoregulation change over time?
sweat glands:
- fixed at infancy
- density decreased on the skin as we grow
- sweat rate efficiency: sweat output per gland
- output controlled by brain in response to heat
differences:
- adults: greater output than children
- children generate more heat per body mass: children rely on convective heat loss more
- females sweat less than males throughout life
How does blood volume change with age and gender?
- increases as we grow
- males have more than females
How do red blood cells (hemoglobin) change with age and gender?
hemoglobin grows at same rate as body mass and blood volume
How does blood change with age and gender?
- starts in 2nd prenatal week
- rapidly increases to birth
- gradually increases into childhood and adolescence
- sex differences show up in puberty (males have more volume)
How does basal metabolic rate change with age and gender?
- declines after infancy to old age (since major organs decrease in size compared to rest of body)
- males higher BMR than females at all ages (~5-10%); fat is less metabolically active than lean body tissue
How does muscular strength change with age and gender?
- increases with age for both sexes
- peaks at age 25-29 years old
- dominant side slightly stronger. Legs contribute to 60% of total strength
How does muscular endurance change with age and gender?
- children get better at push up and pull up performance over time
- puberty: males continue to increase, females level off
What is a better indicator of flexibility than age?
Activity levels
Are females or males more flexible?
females
How does flexibility change with age and gender?
- flexibility increases through childhood
- males and females both decline around or beyond puberty
- activity levels are more of an indicator
- females more flexible at all ages
Physiological maturity and motor performance peak at age
25-30 and declines from there. Significant drops by age 70
How does cardiorespiratory function change with advanced aging?
- VO2 max drops (30%)
- cardiac output declines (~ 30%)
- anaerobic power drops (~40%)
- blood pressure increases
- respiratory function declines:
→ vital capacity drops (40%)
→ residual lung volume increases (~25-50%)
→ loss of alveoli and capillaries
→ pulmonary elasticity decreases
→ airways close
How do muscles change with advances aging?
Muscle decreases in:
- muscle mass (~25-30%)
- size and # of fibers in motor units
- type II muscle fibers
- muscles force (~25-30%)
How does flexibility change with advanced aging?
- declines gradually
- lower back flexibility sharply declines (ages 30-49)
- joints less stable
- conditions like osteoarthritis
Describe body proportions at birth
- head is large
- head, shoulder, and hips close to the same width
- trunk is larger than legs
Describe body proportions throughout childhood
- boys and girls grow similarly. cephalocaudal and proximodistal growth
- legs and trunk ration steadily declines
How do body proportions change with puberty?
- boys grow shoulders more than girls
- girls grow hips more than boys
- ratio between trunk and legs very low
How does body proportion change into adulthood?
- head is a third of shoulder width
- shoulders are usuallt wider than the hips
- sitting heigh it about 50% of total height
What are the sex differences in growth for girls?
- puberty @ 10-13 years
- start puberty earlier than boys
- estrogen increases 10 fold
- taller than boys initially
- reach skeletal maturity earlier
- less weight gain than boys
- body fat continues to gain
- no significant gains in skeletal muscle tissue
What are the sex differences in growth for boys?
- puberty @ 12-15 years old
- start puberty later than girls
- testosterone increase 10-fold
- taller than girls by end
- greater weight gains than girls
- body fat slows down
- significant gains in skeletal muscle tissue
How is the physiology of a child different compared to an adult?
- small heart and lung size
- low stroke volume, cardiac output
- more fatigue from working
- low anaerobic capacity
- less tolerant to heat stress
How is the physiology of an adult different compared to an child?
- larger heart and lung size
- larger stoke volume, cardiac output, lung volume, more efficient breathing
- less fatigue from working
- higher anaerobic capacity
- more tolerant to heat stress
- muscle strength and endurance increases
How is the physiology of females different compared to an males?
after age 10, compared to males:
- aerobic power grows until age 14
- lower VO2 max (due to body mass)
- lower cardiac output, stroke volume
- lower vital capacity
- lower blood volume
- less muscle strength
throughout, compared to males:
- less anaerobic power
- lower BMR
- more flexible
- sweat loss
How is the physiology of males different compared to an females?
After age 10, compared to females:
- aerobic power grows until age 18
- higher VO2 max (due to body mass)
- higher cardiac output and stroke volume (due to larger heart)
- higher vital capacity
- more blood volume
- more muscle strength
Throughout, compared to females:
- more anaerobic power
- higher BMR
- less flexible
- sweat more
