Puberty Flashcards
Define puberty
Describe the physiological, morphological and behavioural changes as the gonads switch from infantiles to adult forms
What is the first sign of girls going through puberty
Menarche (first menstrual bleeding)
What is the first sign of puberty in boys
First ejaculation, often nocturnal
What hormone regulates the growth of female and breast genitalia
Ovarian oestrogen
What hormones control public and axillary hair
Ovarian and adrenal androgens
What hormones control the development of external genitalis and pubic hair growth + enlargement of larynx and laryngeal muscles (voice deepening)
Tetsicular androgens
Describe the tanner stages of development for males
Stage 1:
No pubic hair
Testicular length: <2.5 cm
Testicular volume: <3.0 mL
Stage 2:
Sparse growth of curly pubic hair at base of penis
Testes > 3mL
Scrotum thinning and reddening
Stage 3:
Thicker, curlier hair spreads to mons pubis
Growth of penis in width and length: further growth of testes
Stage 4:
Adult-type hair, not spread to medial surfaces of the thigh
Penis further enlarged; testes larger, darker scrotal skin colour
Stage 5:
Adult-type hair spread to medial surface of thighs
Genital adult size and shape
Describe the tanner stages of development for females
Stage 1:
Prepubertal: No pubic hair
Elevation of papilla only
Stage 2: Sparse growth of long, straight minimally pigmented, mainly on labia
Breast bud palpable: enlargement of areola
Stage 3: Darker, coarser hair spreading over mons pubis
Further enlargement of breast and areola with no separation of contours
Stage 4:
Thick adult-type hair, not yet spread to medial surface of thighs
Projection of areola and papilla to form secondary mound above level of breast
Stage 5: Hair adult-type and distributed in classic inverse triangle
Adult contour breast with projection of papilla only
How long does breast development take
3 years
3 effects of oestrogen on the breast
- Ductal proliferation
- Site specific adipose deposition
- Enlargement of the areola and nipple
What three other hormones than oestrogen are involved in breast development
- Prolactin
- Glucocorticoids
- Insulin
How does the corpus:cervix ration change from prepubertal to pubertal
From 1:2 to 2:1
How does the shape of the uterus change from prepubertal to pubertal
Tubular shape to pear shape
Length change of the uterus
From 2-3 cm to 5-8cm
How does the volume of the uterus change
0.4-1.6 ml to 3-15ml
How does the endometrium change in the uterus
From single layer of cuboidal cells it increases in thickness
What three things does a doctor look out for in a pelvic ultrasound to ensure pubic development is occurring
- Are the Mullein structures present
- Morphology of the uterus
- Morphology of the ovaries
What is the vagina lined by prepubertally
Thin columnar epithelium
What is the vagina lined by post puberty
Thickening of the epithelium - stratified squamous epithelium formation
How does the pH in the vagina change
pH neutral to 3.8
What happens to the length of the vagina
3.5cm to 8cm
How does oestrogen effect the maturation of external genitalia
- Labia majora and minor increase in size and thickness
- Rogation and change in colour of major
- Hymen Thickens
- Clitoris enlarged
- Vestibular glands begin secretion
What is precocious puberty
Onset of secondary sexual characteristics before 8 (girls) and 9(boys)
What is delayed puberty
Absence of secondary sexual characteristics by 14 (girls) and 16 (boys)
Complications of delayed puberty
Reduced peak bone mass and osteoporosis
Where is inhibit produced
Females - pituitary gland, corpus luteum
Males - Sertoli cells
Role of inhibin
Surpresses FSH
What inhibits inhibin
GnRH (enhanced by insulin-like growth factor-1)
How is FSH and LH secretion regulated
Circadian rhythms (pulse like)
When during the day is LH produced during early stages of puberty
Sleep
When is LH produced in late puberty
During the day
What is the hypothalamic maturation hypothesis
- Puberty only requires increased hypothalamic GnRH
- Emphasises direct link in CNA and pituitary/hypothalamic GnRH neutrons
- Supporting evidence from rhesus macaque
Role of Kisspeptin
Stimulates primary puberty by releasing GnRH at the hypothalamus
What happens to the level of glutamate and kisspeptin at the start of puberty
Increased
What levels decrease at the start of puberty
Secretions of GABA and opioidergic neutrons (decreases inhibitory tones)
What is Adrenarche
Maturational process of adrenal gland
What happens during adrenarche
Developmental process where a specialised subset of cells arises forming the androgen-producing zona reticularis
What happens to the levels of hormones produced in adrenal glands during adrenarche
Increased DHEA, DHEA-S
Signs of adrenarche
Body odour
Oily Skin
Mild Acne
Axillary hair
What is Pubarche
Result of androgen action (andrenarche) on the pilosebaceous unit transforming vellus hair into terminal hair in hair-growth prone parts of the skin
Name the g-couples receptor that kisspeptin binds o
GPR54
How common is precocious puberty
1 in 5,000
What sex is precocious puberty most common in
90% of females
What should we rule out before suspecting precocious puberty
Ruling out brain tumour
What is precocious pseudo puberty
Secondary sexual development induced by sex steroids from abnormal sources (adrenal glands)
How do we differentiate between Precocious puberty and precocious pseudo puberty
LH:FSH ratio > 1 - precocious puberty
LH:FSH < 1 - precocious pseudo puberty
How is precocious puberty treated
GnRH super-agonist to suppress pulsatility of GnRH secretion
What are the causes of precocious puberty (GnRH dependant)
- Idiopathic precocious puberty
- CNS tumours
- CNS disorders
- Secondary central precocious puberty
- Psychosocial
What are the causes of precocious pseudo-puberty
- Increased androgen secretion
- Gonadotropin secreting tumours
- McCune-Albright Syndrome
- Ovarian cyst
- Oestrogen secreting neoplasm
- Iatrogenic or exogenous sex hormones
What 3 causes are there of delayed puberty
- Delayed activation of the hypothalamic pulse generator
- Hypogonadotrophic hypogonadism
- Hypergonadotrophic hypogonadism
How does delay in puberty effect repodocution and bone mass
Reproduction defects
Reduced peak bone mass
What are indications for delayed puberty in girls
- Lack of breast development by 13
- More than 5 years between breast development and Menarche
- Lackof pubic hair by 14
- Absent menarche by 15-16
What are indications for delayed puberty in boys
- Lack of testicular enlargement by 14
- Lack of pubic hair by 15
- More than 5 years to complete genital enlargement
