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Questions and Answers
What is menarche?
What is menarche?
What hormone causes the growth spurt before menarche?
What hormone causes the growth spurt before menarche?
What is the effect of increasing quantities of oestrogen secreted by the ovaries?
What is the effect of increasing quantities of oestrogen secreted by the ovaries?
What hormones are induced by GnRH from the pituitary gland?
What hormones are induced by GnRH from the pituitary gland?
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What is the average age at menarche?
What is the average age at menarche?
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What is the effect of greater body fat in girls on menarche?
What is the effect of greater body fat in girls on menarche?
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What is the effect of low body weight on menarche?
What is the effect of low body weight on menarche?
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Study Notes
Menarche and Effects of Oestrogen and Progesterone on Body Tissues
- Menarche is the onset of menstruation which is preceded by the release of hormones from the pituitary gland and ovaries.
- Human growth hormone (hGH) causes the growth spurt which begins 3 to 4 years before the menarche.
- Increasing quantities of oestrogen are secreted by the ovaries and reduce hGH secretion, slowing down physical growth as menarche approaches.
- GnRH induces the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland, which, in turn, induce the secretion and release of oestrogen and progesterone into the circulation.
- Hormonal changes persist until after the age of 40 when changes presaging the menopause begin.
- The rapid rise of LH, mediated by kisspeptin and GnRH, induces the onset of menarche, but other factors are also involved, including an increase in the fat-to-lean ratio of body composition.
- The average age at menarche fell from 15-17 years to 13-13.5 years between the early 1800s and the mid-1900s due to better childhood nutrition.
- The greater amount of body fat in girls today permits the greater aromatization of androgens to oestrogens, leading to the LH surge that precedes the menarche.
- The menarche may be delayed in women who are of low body weight, such as ballet dancers, women who have anorexia nervosa, or those who exercise excessively.
- Oestradiol is the most active and predominant oestrogen in the reproductive years, transported in the blood to tissues that have oestrogen-binding receptors.
- Oestradiol stimulates the growth of the vulva and the vagina, causing proliferation of both the epithelial and the muscular layers.
- Oestradiol causes endometrial proliferation, stimulating the growth of the glands and stroma, as well as the growth of the muscular layers of the uterus.
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Description
Test your knowledge of menarche and the effects of oestrogen and progesterone on body tissues with this informative quiz. From the onset of menstruation to the changes in hormone secretion, this quiz will cover everything you need to know about these important topics. Challenge yourself and see how well you understand the fascinating world of female reproductive health.
