Physiology of Growth ✅ Flashcards
What can the pattern of normal growth be subdivided into?
3 phases
What are the phases of normal growth?
- Infancy
- Childhood
- Pubertal
What is the infancy phase of growth driven by?
Largely by nutritional factors
What does the infancy phase of growth depend on?
- Normal placental function
- Nutritional intake in early life
When can the infancy phase of growth be considered to start?
Conception
How long does the infancy phase of growth last?
The first 2 years of postnatal life
What is the childhood phase of growth dependent on?
- GH
- IGF-1
- Thyroxine
When does the childhood phase of growth start?
Postnatally
When does the childhood phase of growth last until?
The end of puberty
What is the pubertal phase of growth driven by?
Increasing gonadal production of sex steroids
What is the effect of increasing gonadal production of sex steroids on growth?
It stimulates GH secretion
What do the phases of growth produce when superimposed?
The normal growth pattern
What happens to the height velocity during the first 2 years of life?
It falls rapidly from approximately 25cm/year to 5-7cm/year
When does the height velocity increase again?
At the onset of the pubertal growth spurt
What does the pubertal growth spurt coincide with in girls?
The onset of breath development
At what age does the pubertal growth spurt peak in girls?
12 years
What does the peak growth velocity coincide with in boys?
Testicular volumes of 15ml
How does the timing of the pubertal growth spurt in boys compare to that in girls?
Typically occurs 2 years later in boys
What is the average height difference between adult men and women?
Men are 12.5-14cm taller on average
Why do men have a taller average adult height?
- Longer prepubertal contribution to growth
- Greater peak height velocity seen in boys
