15. Physiology of puberty

name two types of precocious puberty

1) central/true precocious puberty 2) peripheral/pseudo precocious puberty

what are the three main changes that occur during puberty

1) growth spurt 2) secondary sexual characteristics develop 3) menarche/spermatogenesis

what is the average age a girl starts her periods

10-16

in girls what is the average age to start puberty?

10.9 years (8.5-13.3)

describe the average age of puberty in boys

11.2 (9.2-14.2)

an increase of which hormone stimulates the adrenals to grow pubic hair and axillary hair

ACTH

what is the active from of testosterone, which is converted in the target organs?

DHT

what is the treatment for central/true precocious puberty?

GnRH agonist - stops pubertal progression (p.gland ignores signals from the hypothalamus which prevents the stimulation of the ovaries). Treatment is stopped at age 10-12 and then puberty progression will resume.

during puberty explain the change of GnRH control

before puberty= GnRH is supressed by natural mechanisms age 6-9= pulsatile nocturnal release of GnRH every 90-120 minutes

what is the most common cause of pseudo-precocious puberty

congenital adrenal hyperplasia

what does therlarche mean?

early development of breasts around age 2-3

what does adrenarche mean?

early development of pubic hair

what age is considered "early puberty" in girls and boys

girls=under 8 boys=under 9

describe what central/true precocious puberty is

gonadotrophin dependent premature activation of the HPG axis.

describe what pseudo-precocious puberty is

gonadotrophin independent the gonads develop independently of GnRH - no normal pattern of puberty, testosterone, LH and FSH are high.

describe the development that occurs in girls in chronological order

growth spurt-->breast growth-->pubic hair growth-->axillary hair-->menstruation

explain how GnRH levels effect LH and FSH levels

increase in GnRH= increase in LH and FSH

name 3 causes of delayed puberty

klinefelters syndrome, turners syndrome, gonadotrophin deficiency

androgens are produced by which cell under the control of which hormone?

leydig cells under LH control

if someone has gonadotrophin deficiency what is the treatment?

lifelong testosterone replacement therapy

why is early puberty worying?

may be a sinister underlying cause, eg swelling of hypothalamus (80% of boys) , emotional and psycho-social difficulties,decreased adult height

what age is considered delayed puberty in males and females?

over 14

describe the ovarian cycle

primary oocyte (within follicle)-->growth of follicle-->mature follicle-->follicle ruptures-->secondary oocyte is released-->corpus luteum forms-->corpus luteum degenerates-->primary oocyte forms

sperm is produced by which cells under the control of which hormone?

sertoli cells under FSH control

name the triad associated with turners syndrome which causes delayed puberty

short stature, streak gonads, primary amenorrhoea

describe what happens to boys during puberty in chronological order

testicular volume increases-->penile length-->pubic hair-->growth spurt--> axillary/facial hair-->deep voice

describe what is meant by "precocious puberty"

the presence of true pubertal features at a young/inappropriate age

define the term "puberty"

the stage of physical maturation in which an individual becomes physiological capable of procreation.

why is delayed puberty a concern?

underlying cause, far puberty will never occur, emotional and psychosocial upset, short stature, reduced bone mineralisation