HSCI 216 Lecture Notes - Leydig Cell, Zona Reticularis, Cortisol
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16 Jun 2012
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HSCI216: Lecture XI
Growth & Development
Catch-up Growth: height velocity above the limits of normality for age and/or maturity during
a defined period of time, following a transient period of growth inhibition
o Once the inhibitor is removed, they can catch up
Early Developing
o It is dangerous for males to look like an adult when not
As they do compete with others of their gender
o Women mature earlier because it will increase their chances to reproduce before they
die
o Girls who live with their step-father, will mature earlier than those living with their
biological father
Sexual molestation more likely with step-fathers, also murder (even though the
risk is low, it is still higher than biological)
Ex: lions taking over female colony then kill the females offspring for many
reasons
Late Developing
o catch up growth
o growth can be fostered by a drastic change in environment
ex: of girl once adopted her growth spurts greatly
o Growth hormone insufficiency (genetic origin)
Growth in adolescence and puberty
o Puberty: onset of reproductive, physical and behavioral changes leading to adulthood
(recognize the three changes)
o Adolescent growth spurt: onset of pubertal growth spurt is earlier in girls than boys
Girls: 10-13, boys: 15-17 (there is a distribution as well)
Girls stop growing early as well
If you grow later, you grow from a higher stature, therefore taller at the end\
Sexually dimorphic: one form for females, another for men
Boys grow for longer period of time
o Tempo of growth during adolescence: variation between populations in growth, no
correlation between timing of growth spurt and final stature, genetic control for tempo
of growth
All same age, but develop at different rates
Puberty: transition from growth maintenance reproduction maintenance
o At the end of reproduction maintenance we senesce
o Timing of puberty is sensitive to internal (developmental) and external (ecological)
o Precise proximate determinants remain obscure
Ultimate: delay will help living conditions from previous generations
Hypothalamic-Pituitary-Gondal (HPG) axis (the hypothalamus & pituitary gland) driving
factors for puberty
o Hypothalamus: control center for HPG axis (gonads testicles and ovaries), through
gonadotropin-releasing hormone or GnRH
Tropin = growth, increase etc. therefore gonadotropin increase growth of
gonads