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20 Cards in this Set

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  • Back
ethnic disparities in onset of puberty and menarche
blacks first, then Hisp, then NH whites
hypo-pit-gonadal axis in embryo-->kids
2nd trimester fetus:
-arcuate nucleus of hypothalamus has autorhythmicity: secretes GnRH in pulsatile manner (every 60-90 min)
-fetal gonadotropin levels peak at midgestation, then decline to low levels at term
-gonadotropin levels decline to nadirs at age 3 in boys and 4 in girls & remain low til onset of puberty
first measurable event indicating onset of puberty;
what causes it?
incr gonadotropin (LH, FSH) secretion during sleep (d/t reactivation of pulsatile GnRH from hypo)
endocrinologic marker of adult reproductive fxn in women
development of positive feedback (=ability of pituitary to respond to high levels of sex hormones with surge of secretory activity--i.e. surge of LH)
what trigges ovulation and luterinization of follicle
-happens before puberty (6-9 y/o)
-refers to changes in adrenal cortex
-increased activities of:
A. 17-20 desmolase (First Aid, p. 263: converts cholesterol-->pregnenolone and initiates production of all adrenal sterids)
B. 17-hydroxylase (allows production of glucocorticoid and sex hormones)
what can lead to hirsutism
abnl adrenarche: xs adrenal androgen production
what can lead to hyperandrogenic chronic anovulation (polycystic ovary syndrome)
abnl adrenarche: xs adrenal androgen production
what alloows gonadotropin prodution to incr during puberty
CNS becomes less sensitive to gonadal negative feedback ("resetting the gonadostat")
what is necessary for puberty to begin
1. critical weight & body fat (24%)
2. leptin (necessary but not sufficient signal for pubertal onset)

also, hyperinsulinemia and insulin resistance can cause early onset puberty
first sign of puberty in girls
breast budding
first sign of puberty in boys
enlargement of gonads (followed soon by enlargement of phallus)
progression of puberty in girls
1. breast budding
2. pubic hair
3. menarche
progression of puberty in boys
1. enlargement of gonads
2. enlargemet of penis
3. pubic hair
4. first ejaculation of semen (spermarche)

(parallel's girls progression:
1. enlargement of breasts (breast budding)
2. pubic hair
3. menarche)
when does axillary hair develop
(both boys and girls)
2 yrs after pubic hair
Tanner stages
Stage 1:
-female breast: elevation of papillae (nipple) only
-pubic hair: vellus hair
-male genitalia: preadolescent

Stage 2 (1st sign of puberty)
-female breast: breast bud (=1st sign of puberty), enlargement of areola (colored area surrounding nipple AKA papillae)
-pubic hair: sparse, straight hair on labia
-male genitalia: ENLARGED TESTES (=1st sign of puberty), scrotal skin changes texture

Stage 3:
-female breast: further enlargement, no separation of contours
-pubic hair: coarser hair to jxn of pubes
-male genitalia: PENILE ENLARGEMENT (first length, then breadth)

Stage 4:
-female breast: projection of areola & papilla above breast
-pubic hair: adult hair, but not on inner thighs
-male genitalia: dev of glans penis, darkened scrotal skin

Stage 5:
-female breast: mature, recession of areola
-pubic hair: mature; spread to inner thighs
-male genitalia: mature
how do gonadal steroids affect pubertal growth
1.incr GH
2.incr IGF-1 (liver, cartilage, bone)
somatic growth in girls vs. boys
Girls begin pubertal growth 2 yrs earlier than boys. Thus:
1. girls are shorter at onset of accelerated growth.
2. lnger period of prepubertal growth in boys, so boys end up taller
what determines adult height
1. child's height at pubertal onset
2. amplitude of growth spurt
skeletal maturation in boys vs. girls
biacromial diameter increases much more in boys, while biiliac diameter increases much more in girls