Principles of growth Flashcards
What are the influences on growth?
- Race
- Family
- Puberty- diff hormone secretion
- Gender- males taller than girls
- Nutrition
- Seasonal changes- some grow more in summer than winter
- Environmental changes
- Hormones
Why do boys grow taller than girls?
- bc males have puberty later in life
- more time to grow
- have longer growth spurt
What are the patterns of growth?
- genetics
- nutrition
- environmental
- hormones
How do genetics affect growth?
- if genetic problem from birth = can prevent growth= shunted growth throughout life
What happens if the mother at birth is anorexic and stressed?
- very small baby born
What happens if mother at birth has diabetes and is obese?
- fat baby
When does nutrition play the most important part in life?
- 1st year of life
- e.g. if GH deficiency= growth no happen
How do hormones affect growth?
- childhood= growth and thyroid hormones
- puberty= sex hormones = more growth hormone- growth spurt
Which phase is the most rapid growth phase?
- prenatal
What happens in the first trimester?
- rapid growth of organs
- differentiation of organs
- form embryonic disc layers:
- ectoderm (skin, hair, brain, nerves)
- mesoderm (cardiac, skeletal, renal, bloods)
- endoderm (lung, gut, thyroid, pancreas)
What happens in the 2nd trimester?
- cellular hypertrophy (rapid cellular division)
- get peak foetal length velocity of 2.5cm per week
What happens in the 3rd trimester?
- maturation of organs
- max weight gain
- near term= subcutaneous fat added to the embryo
What factors affect prenatal growth?
- in utero, extrinsic factors play bigger role than intrinsic factors
- hormones
What are the extrinsic factors in utero?
- placenta
- blood flow
- nutrition to baby
- maternal anatomy
- maternal size
- maternal nutrition
What are intrinsic factors?
- genetics
- hormone function of embryo
What hormones are involved in utero prenatal growth?
- growth hormone
- IGF I and II
- thyroid
- foetal glucocorticoid (cortisol)
Growth hormone:
- GH secretion high in foetus
- not too big influence on foetal growth
Insulin like growth factors I and II:
- big role in foetal growth and development
- higher IGFII secretion
- IGFI more closely related to foetal growth
Thyroids:
- normally Thyroid hormone not present in foetus
- doesnt affect foetus growth
Foetal glucocorticoid (glucose):
- in utero tissue differentiation
- development of organs e.g. liver, lung
What does birth size depend on?
- in utero environment
What is the average birth size?
- 48-51cm
What is the average birth weight?
- 2.7kg to 4.1kg
What are the variations babies can be born with?
- small for gestational age
- large for gestational age
What is the correlation between birth size and adult size?
- WEAK
What is difference between males and females?
males normally:
- 150g heavier
- 0.9cm longer
- slightly greater muscle mass
- maybe bc of more testosterone near term (called mini adolescence)
What is the kalberg’s ICP model?
- I: infancy
- C: childhood
- P: puberty
- it breaks down growth mathematically
- allows you to detect and understand growth failure
What is height velocity?
- records how much child grows in a year
What is the height velocity of children?
- in the first 2 years of life= VERY FAST
- childhood= SLOWS DOWN becomes nearly constan (4cm to 8cm a year)
- Puberty = GROWTH SPURT
= girls smaller growth spurt
= girls have it before boys