Puberty Flashcards
Describe the sequence of events that takes place in puberty in females
Describe the sequence of events that takes place in puberty in males
What scale is used to describe the stags of puberty?
The Tanner Scale
What role does oestrogen play in somatic growth?
Oestrogen closes the epiphyseal growth plates of long bones in both sexes
With regards to oestrogen, why are boys usually taller than girls?
- Oestrogen needed to close growth plates
- Lower levels of oestrogen in boys vs girls means it takes longer for growth plates to fuse
- Meaning more time for growth
What is aromatisation?
The conversion of testosterone to oestrogen
What weight is deemed critical in girls for menarche to begin?
47 kg
How can precocious puberty lead to altered adult height?
Precocious puberty causes oesterogen levels rising earlier → growth plates fuse earlier → results in short stature
Identify the hormones at each stage of the HPG axis
In what manner is GnRH released from the Hypothalmus?
Pulsatile manner, synchronised with external signals
How can pineal tumours cause precocious puberty?
Pineal gland is closely located to the hypothalmus
A pineal gland tumour can cause compression of the hypothalmus wich stimulates GnRH early
Why might precocious puberty be stimulated by intra cranial pathology such as meningitis?
Meningitis can stimulate the hypothalmus to release GnRH
How might you delay precocious puberty?
Give constant (not pulsatile) GnRH to densnsitise GnRH receptors and delay puberty
When are levels of LH and FSH highest?
During sleep
Why are testosterone levels highest in the morning?
- GnRH is released highest levels at night
- Acts on anterior pituitary to release LH &FSH
- LH stimulates Leydig cells of testes to produce Testosterone
- As this happens at night, levels will be highest in the morning
There are 2 different cell types of an ovary, which cell type responds to LH and which responds to FSH
Granulosa cells = respond to FSH
Theca cells = respond to LH
How does the level of oestrogen/ progesterone alter negative feedback on GnRH production?
- Low oestrogen → negative feedback on GnRH
- High oestrogen → positive feedback on GnRH causing LH surge
- High oestrogen & Progesterone → prevents + feedback meaning no LH surge
What does inhibin do?
Inhibin secretreted from granulosa cells of corpus luteum and inhibits FSH
How does Leptin affect the HPG axis?
Leptin feeds back to CNS information on energy stores
Regulates secretion on GnRH
