Hypothalamic - Pituitary - Gonadal Axis II Flashcards
What is puberty the transition from and to?
β Non reproductive to reproductive state
What are the 4 main things that happen during puberty?
βBreast development in females and increased testicular volume in males.
βSecondary characteristics develop
βProfound physiological changes
βProfound psychological changes
What is gonadarche characterized by?
β An increase in GnRH ( measured through FSH and LH)
What does an increase in LH result in?
β Secondary sex characteristics
Why does adrenarche occur?
β Increase in adrenal androgen secretion due to cellular remodelling of adrenal cortex.
What are the adrenal androgens?
βDehydro-epiandrosterone (DHEA)
βDehydro-epiandrosterone sulphate (DHEAS)
Where are the adrenal androgens secreted from?
β The zona reticularis (cortex)
What is pubarche the result of?
β Adrenarche
What appears during pubarche and why?
βAppearance of pubic/axillary hair resulting from adrenal androgen secretion
What is pubarche associated with?
β an increase in sebum production which leads to acne
What is acne caused by?
β Infection and abnormal keratinization
When is puberty considered precocious?
β 8 years old in girls
β 9 years in boys
When does gonadarche happen?
β several years after adrenarche
What happens during gonadarche?
β Reactivation of hypothalamic GnRH
What is the HPG axis required for?
β male differentiation during fetal development
When are the GnRH neurons not restrained anymore?
β until gonadarche
What does the activation of gonadal steroid production cause?
β The production of viable gametes and the ability to reproduce
What hormones does the hypothalamus produce?
β Kisspeptin
β Gonadotrophin releasing hormone
What hormones does the pituitary release?
β Gonadotrophin hormones
What is GnRH secreted and synthesized by?
β Specialist hypothalamic centres (arcuate nucleus)