Puberty Flashcards
Prepubertal Development:
When does brain growth plateau?
6-8 yrs
Are the ovaries essential for female prepubertal development?
No
The Migration of the testes to scrotal position is mediated by which 2 ligaments?
Gubernaculum and Suspensory ligaments
What kind of activity does the neonatal HPG axis undertake at birth until puberty?
Transient
What week does sexual differentation occur?
5-6 Wks
Fetal development:
At what week does the hypothalamic neural cells secreted GnRH?
Wk 11
Prepubertal testosterone levels:
Fetal: onset of secretion?
Secretion from 8-10 weeks onwards
Prepubertal testosterone levels:
Prenatal: Peaks at what week? How much T?
PEaks at wk 13- 15 (2ng/ml)
Prepubertal testosterone levels:
Post natal: Peaks when? How much? When is the decline
Peaks @ 3 months after birth (2-3ng/ml)
Postnatal decline at 3-4months.
Prepubertal testosterone levels:
What happens to testosterone levels at 1yr after birth? (Concentration?)
Second modest rise until prepubertal peak (9ng/ml)
Triggers of puberty:
Sleep, explain?
Earlyin puberty, GnRH is released during sleep -> long term development of pulsative GnRH release w/ positive feedback initiating ovulation or spermatogenesis.
Helps perpetuate further release of LH and FSH from Pit. = Gonadal development.
Triggers of puberty:
Leptin?
Before puberty leptin levels rise in proportion to adipose tissue mass (fat levels). Leptin may be a way for the body to tell the hypothalamus that (Dude we got enough long term energy storage lets go). But also there is a growth hormone- induced acceleration of body growth- increase body weight.
What trigger puberty, Secondary factors?
- psychological factors (internal)
- happiness vs. stress
- environmental stimuli (external)
- smell
- photoperiod in some species
- circadian (circa = approximately, diem = day) rhythms
- supra chiasmatic nuclei (tiny region in brain controlling circadian rhythms
- circannual rhythms
- circadian (circa = approximately, diem = day) rhythms
- colours
- temperature (more relevant to animals)
Female Tanner stages (5)
P1: Prepubertal.
P2: Early development of subareolar breast bud and small amounts of pubic hair and axillary hair.
P3: Increase in size of palpable breast tissue and areolae, increase in pubic/axillary hair
P4: Breast tissue and areolae protrude above breast level. Further increase in hair development.
P5: Mature adult breast Complete pubic/axillary growth
What is the first sign of female puberty?
Thelarche (Breast development)
What hormones initiate breast growth?
Oestrogen, Prolactin and GH
Male Tanner stages
P1: Prepubertal, testicular volume <1.5ml
P2: Testicular volume between 1.6-6ml. Small amounts of axillary and pubic hair (9-11 year)
P3: Testicular volume 6-12ml, lengthening of penis and areola, increase in pubic/axillary hair (11-12.5 yrs)
P4: Testicular volume 12-20ml, scrotum enlarges + darkens. (12.5-14 yrs) Further increase in hair development
P5: Testicular volume (>20ml). Adult genitalia
What hormone is higher during puberty than adulthood (Male + Female)?
LH
Reproductive function and maturation is coordinated by the …
Hypothalamic-pituitary-gonadal axis
What is the most significant structural remodelling during female puberty?
Uterine Chages
What hormones cause uterine remodelling during puberty?
Oestrogen, Progesterone, Prolactin and Growth Factors
When does the second stage of sertoli cell and germ cell proliferation occur?
Puberty
What does this show?
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Endocrine control of puberty and spermatogenesis in males
What are the target cells of FSH in Males?
Sertoli cells
What are the target cells of LH in males?
Leydig cells
What are the target cells of LH in females?
Theca Cells
What cells are the target of FSH in females?
Granulosa cells
When is the prostate fully functionally grown?
Puberty
What characteristics are defined by the sexual dimophism of the musculoskeletal system?
- Enlarged pelvis in females and enlarged shoulders in males
- Men: 1.5x more lean body mass and 1.5x more skeleton than women
- Women: 2x more body fat
What hormones are responsible for the closure of epihpyses?
Oestrogen and Thyroid hormones
What are the characteristics of sexual dimorphism of the respiratory system?
- Male larynx grows by 1/3 of its adult size (also laryngeal prominence)
- Thickening and lengthening of the vocal cords in males
- Lowers pitch of voice.
What are the four characteristic features of the pubertal development of the integumentary system?
- Hair Growth (Male thick, Female Fine)
- Hypodermic fat (cellulite) accumulation (Females, oestrogen)
- Activation of sebaceous glands (Testosteron and oestrogen)
- Development of axillary and anogenital ‘sweat’ glands.
- Controlled by androgen
- secrete viscous odorless sweat, proteins and fat substances.
- activated by sympathetic nerves and sexual foreplay.
What are the characteristics of the pubertal changes of the cardiovascular system? (4)
- Increased blood volume
- Increased interstitial fluid (oestrogen caused)
- Decreased plasma cholesterol
- Possibility of anaemia (Females)
What are the characteristic changes in the nervous system during puberty?
Mental maturation
Fatigue and Depression
Sexual Drive
Sexual Behaviour
What is sexual age determined by in males and females?
Males: Testicular and penile size, hair growth
Females: Thelarche, menarche, hair growth
What % increase in body size occurs during puberty?
20%
What years does puberty occur in females
9-13
Whats years does puberty occur in males?
11-15 yrs
Does puberty last longer in mals or females?
Males
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What is Precocious Puberty?
Dveelopment of secondary sexual characteristics before the age of:
8yrs in Women
9yrs in Men
What % of the population shows precocious or delayed puberty?
5%
What are he two main types of precocious puberty?
Gonadotrophin-independent (Peripheral)
Gonadotrophin-dependent
Gonadotrophin-independent precocious puberty caused by
Testicular disorders and tumors
Ovarian disorders and tumors
Gonadotrophin-independent precocious puberty causes (symptoms)
Increased gonadal steroid secretions
Increased adrenal androgen (in males)
Gonadotrophin-dependent PP is caused by:
CNS tumors
Other pathologies and lesions
Idiopatic: 2/3rds of cases, 90% of female precocious puberty
Gonadotrophin-dependent PP causes (symptoms)`:
Early reactivation of the HPG axis
Increased production of GnRH/ Gonadotrophins
What is Delayed Puberty?
Failure to achieve sexual maturation at two years after the mean normal age of puberty • girls (normally 9-13 years) • boys (normally 11-15 years)
What is delayed puberty caused by?
Hypogonadotrophic hypogonadism
Hypergonadotrophic hypogonadism
What causes hypogonadotrophic hypogonadism?
CNS disorders & gonadotrophin deficiency
Gonadal dysgenesis and failure
What causes hypergonadotrophic hypogonadism?
LHR (receptor) and FSHF mutations
Turner Syndrome, 45X female
Klinefelter syndrome, 47XXY male
What is Anovulatory PCOS?
Chronic inability to produce preovulatory follicles, - no ovulation and mestrual cycle (amenorrhea).
Characterised by:
Hyperandrogenism, masculinsed body shape, hirsutism, obesity, acne
How many women have PCOS and it causes what % of female infertility and anovulatory infertilty?
23% of all women have it
10% of all women infertility
50% of all anovulatory infertility
Male erectile dysfunction affects how many men?
>150 M men worldwide
What is male erectile dysfunction caused by?
Vascular aetiology:
- Atheroschlerosis of pudendal artery and branches
- Failure of veno-occlusive mechanism (venous leak)
- Impaired smooth muscle relaxation
What is the danger of untreated cryptorchidism?
Infertility
Increased incidence of testicular cancer in males
6% of isosexual female puberty causes
malignancies of the female genital tract
What female genital tract malignancy risk factor is increase by 6 fold in teenage pregnancy?
Gestational trophoblastic tumour
Teenage girls whose mothers recieved diethylstilboestrol (DES) during pregnancy have an increased risk of …
Clear cell carcinoma of the vagina
What percent of precocious puberty is idiopathic in females?
66%
What is the female:male ratio of precocious puberty?
10:1
What does a GPR54 mutation cause?
Delayed puberty