Flashcards in Week 3.0 - Puberty and menopause Deck (53)
-Development of axillary and pubic hair
-First menstrual period
-onset of increased androgen secretion
What is puberty?
-Stage of human development when sexual maturation and growth are completed and results in the ability to reproduce
Who begins puberty first girls or boys?
-Development of breast
Describe the main features of puberty
-Accelerated somatic growth
-maturation of gonads and genitals
-Development of secondary sexual characteristics
-Menstruation and spermatogenesis begins (reproductive system inactive before this)
With what hormonal changes is the onset of puberty associated with?
-Gradual activation of GnRH causing steady rise in FSH and LH
-Increased secretion of oestrogens and androgens
-Extragonadal hormonal changes -> elevation of adrenal steroids and IGF-1
Which hormones is the growth spurt dependent upon?
-Sex steroid hormones
What is the difference between the growth spurt in girls and boys?
-Earlier and shorter in girls
(men are larger because growth spurt longer and slightly faster)
What signifies the end of the growth spurt?
What causes the growth spurt to be shorter in girls?
-Oestrogen closes the epiphyseal plates earlier
What controls the rate of genital development in boys?
When does puberty typically begin in girls?
-8-13 years (mean 11.5 years)
When does puberty typically begin in boys?
-10-14 years (mean 12.5 years)
What is the critical weight for menarche?
What is the relationship between weight and menstruation?
-If weight falls below ~47kgs then reproductive cycle will cease
-Overweight tend to start period early
-Obesity can also interfere with normal menstruation
Name one environmental factor thought to influence puberty?
-Light/dark exposure ie day length
What happens to the LH pulses on lead upto puberty?
-Pulses are negligible and then increase in amplitude and frequency
What is the first phenotypic change in girls?
What is the first phenotypic change in boys?
What is the relationship between sleep and LH?
-LH secretion is associated with REM sleep and begins as nocturnal pulsatility which causes a noturnal increase in sex steroid secretion
What initiates gonadal development in puberty?
-high levels of FSH and LH secretion
What happens after the gonads have started to develop in males?
-Spermatogenesis and androgen secretion begins
-Androgens initiate growth of sex accessory structures (eg prostate) and secondary sex characteristics
The adrenal glands secrete androgens, why does this not initiate puberty?
-Level too low
What is the relationship between TSH and puberty?
-As puberty starts TSH secretion from pituitary increases leading to increased metabolic rate and promotes tissue growth
What effects do androgens have on growth?
-Cause retention of mineral to support bone and muscle growth
Which sex steroid do sertoli cells secrete?
Which secondary sex characteristics are driven by androgens in females?
-Pubic hair growth
-Sebaceous gland secretion