Puberty and the Menopause Flashcards
How does the HPA axis and the hormones work?
Includes negative feedback of steroids
GnRH is made in the hypothalamus which causes the anterior pituitary gland to release LH in pulses. LH and FSH go into the blood to work on the testes and ovaries. There is a feedback of these steroid hormones on the hypothalamus and anterior pituitary gland (testosterone, inhibins, progesterone etc).
What is Kallmann’s syndrome?
How can it be cured?
This is a GnRH deficiency which causes issues with smell, small stature, sexual immaturity and long arms etc. This can be cured with pulsatile GnRH
Why is timining of puberty important?
Helps with height
What steps does someone need to go through to transition in a sexually mature adult?
When is the second step seen in women vs men
1) Adrenarche (adrenal gland development)
2) Puberty - HPG axis activated (seen in women with menarche which is definitive whereas seen in boys after first ejaculation which is less definitive).
When does adrenarche occur?
Age 8
What does adrenarche cause?
Increased secretion of steroids from the zona reticularis
What is expressed by the gonads?
Testosterone, Estradoil, AMH
How does testosterone fluctuate throughout life and the day?
High at birth then declines,
Increased secretion at night to begin with but then is increased during day in mid-late puberty
How does estradoil fluctuate throughout life?
Birth high then decreases
Puberty - secretion increases once more
How does AMH flucuate throughout life?
Neonate - high and rises steadily through childhood
Puberty - wobble
What time of day does LH secretion occur?
At night
What is menarche and why is it so weird to begin with?
Female puberty which is irregular to begin with due to incomplete cycles and flucuating normal ovulatory cycles and anovulatory cycles. This becomes normal before declining
What does kisspeptin do?
Stimulates GnRh neurones - sex steroids acts on the KISS neurone which signals to the GnRH neuron which increases reproductive function.
How does kisspeptin influence puberty?
Increased action of KiSS-1 mRNA and/or GPR54 mRNA during puberty however knockout of this leads to no puberty.
What type of pathways can influence the hypothalamus and therefore puberty?
Metabolism, inflammation, stress, drugs, steroids (these work on the KNDy neurone reducing kisspeptin and neurokinin B)
GnIH(works straight on the pituitary)
Does Kisspeptin increase the number of pulses of LH?
Yes as it increases GnRH pulses
How does kisspeptin control GnRH signalling?
Kisspeptin neurones have positive feedback from neurokinin and negative from the sex steroids. They signals to the GnRh neurone
Does puberty timing differ between sexes?
Yes, girls enter before boys, however there is big range of normality within genders e.g. one person might be done breast development by 13 however another might not have started.
Do women who go through puberty early end up smaller?
Yes as puberty stops growth
Does puberty start earlier and are people growing taller than in previous years?
Yes probably because we are healthier, eating better etc.
How does leptin influence puberty?
If you weigh to little you wont get puberty and leptin is secreted by fat cells to regulate appetite and energy expenditure
What happens to kissp1 mRNA during fasting and what can this influence?
Is decreases therefore less signalling to GnRH
Does food intake influence puberty?
Yes
Is puberty still getting earlier?
Yes
