Menstruation Essay

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HORMONAL/ MENSTRUAL CYCLE The average length of the menstrual cycle is 28 days, but this can vary between women and from one cycle to the next in individuals. The length of the menstrual cycle is calculated from the first day of the period to the day before the next period starts. Girls get their first period (menarche), on average, between the ages of 11 and 14. By this stage, other sexual characteristics have usually developed, such as pubic hair and budding breasts. Hormones and the menstrual cycle The menstrual cycle is complex and controlled by many different glands and the hormones they produce. A brain structure called the hypothalamus causes the nearby pituitary gland to produce certain chemicals, which prompt the ovaries to produce the sex hormones oestrogen and progesterone. The menstrual cycle is a biofeedback system, which means each structure and gland is affected by the activity of the others. The four main phases of the menstrual cycle are menstruation, the follicular phase, ovulation and the luteal phase. Menstruation Menstruation is the elimination of the thickened lining of the uterus (endometrium) from the body through the vagina. Menstrual fluid contains blood, cells from the lining of the uterus (endometrial cells) and mucus. The average length of a period is between three days and one week, depending on the individual. Sanitary pads or tampons are used to absorb the menstrual flow. Both pads and tampons need to be changed regularly (at least every four hours). Using tampons has been associated with an increased risk of a rare illness called toxic shock syndrome. Follicular phase The follicular phase starts on the first day of menstruation and ends with ovulation. Prompted by the hypothalamus, the pituitary gland releases follicle stimulating hormone (FSH). This hormone stimulates the ovary to produce around five to 20 follicles
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