Menstrual cycle Lecture 2 1 Objectives • To list the phases of the menstrual cycle • To describe the hormonal changes during each phase • To describe the hormonal changes behind ovulation • To point the source and control of the hormones involved in the menstrual cycle 2 What is a menstrual cycle? • The menstrual cycle is the series of changes a woman's body goes through to prepare for a pregnancy. • About once a month, the uterus grows a new lining (endometrium) to get ready for a fertilized egg. • When there is no fertilized egg to start a pregnancy, the uterus sheds its lining. 3 What is a menstrual cycle? • This is the monthly menstrual bleeding (also called menstrual period) that women have from their early teen years until menopause, around age 50. • The menstrual cycle is from Day 1 of bleeding to Day 1 of the next time of bleeding. Although the average cycle is 28 days, it is normal to have a cycle that is shorter or longer. 4 NORMAL MENSTRUAL CYCLE What is the mean duration of the MC? Mean 28 days (only 15% of ♀) Range 21-36 What is the average duration of menses? 3-7days What is the normal estimated blood loss? Approximately 20 – 80 ml When does ovulation occur? Usually day 14 10 -- 12 hrs after the onset of mid-cycle LH surge. How many have women menstrual cycle with life time? 300—400 How many oocyte at birth female has? 2 million 5 What controls the menstrual cycle? • Hypothalamus and pituitary gland send hormone signals back and forth with your ovaries. These signals get the ovaries and uterus ready for a pregnancy. • The hormones estrogen and progesterone play the biggest roles in how the uterus changes during each cycle. • Estrogen builds up the lining of the uterus. • Progesterone increases after an ovary releases an egg (ovulation) 6 Symptoms of painful periods 1. 2. 3. 4. 5. 6. Pains in the abdomen Pain in the vagina Feeling nauseous and generally unwell Diarrhoea Sweating Fatigue 7 Related Terms • Oligomenorrhoea : Irregular, infrequent periods • Menarche: is the age of the first menstrual cycle and culminates at the age of Puberty. • Dysmenorrhea - painful menstruation – Possible cause - prostaglandins • Amenorrhea - absence of menstruation – Primary amenorrhea - when girl has not. • Mittelschmerz - middle pain; cramping in lower abdomen that occurs during ovulation. • Menopause is cessation of regular menstrual cycle. 8 Factors effect of menarche starts 1. 2. 3. 4. 5. Genetics Geographical location. Nutrition Weight Psychological factors 9 Menstrual Cycle Consists of: 1. Ovarian Cycle 2. Endometrial Cycle 10 The Phases of the Menstrual Cycle The overian cycle has 4 phases: 1. Follicular phase - proliferative phase or Pre ovulatory phase 2. Ovulation 3. Luteal phase - secretory phase or postovulatory phase 4. Menstruation 11 The Phases of the ovarian Cycle 1. Follicular phase : • high levels of FSH secreted – Function is to stimulate follicles in the ovaries One follicle begins to mature and brings an egg to maturity 1- 14day – Follicle secretes estrogen – Increase level of estrogen secreted by maturating follicle that effect on the endometrial proliferation. 2. Ovulation phase • Follicle ruptures open and releases the mature egg 14 day promoted by LH surge • Decrease level of estrogen • Life span of ovum is 24 hrs. 12 13 The Phases of the Menstrual Cycle 3. Luteal phase after releasing an egg, the follicle turns into the corpus luteum15 -28day • The corpus luteum secrets progesterone to Prepare endometruim for implantation and to secret glycogen and mucus. • The absence of fertilization the corpus luteum begins to degenerate that will lead Estrogen and Progesterone decrease. 4. Menstruation - shedding of the inner lining of the uterus 28 day. 14 15 16 Endometrial cycle 1.Proliferative phase • Start in day 5 • Start endometrial proliferates in response of estrogen • Increase thickness dramatically from 0.5 – 5mm. • Cervical mucus becomes thin and clear and more alkaline 2. Secretory phase : • begins at ovulation • progesterone secreted by the corpus luteum stimulates the glands of the endometrium to start secreting the nourishing substances preparation of implantation. 17 Endometrial cycle 3. Ischemic phase • If fertilization does not occur, the ischemic phase begins. • Estrogens and progesterone level drop • Corpus luteum degenerate. • Spasm of arterioles and lead of shedding of the endometrium. 4. menstrual phase : • Rupture of spiral arteries • The beginning of menstrual flow marks the end of one menstrual cycle 18 19 Changes in the Uterus: Stage 1- Day 1-5 menstruation Stage 2 Day 5- 13 preovulatory stage Stage 4 Day 15-28 postovulatory stage Stage 3 Day 14 Ovulation Ovarian Hormones Days 1-14 Pituitary Gland Produces FSH Follicle Stimulating Hormone Triggers formation of the Follicle Within the ovary Produces Estrogen & Ovum Triggers uterine lining thickening Days 14 - 28 Pituitary Gland Produces LH Lutinizing Hormone Triggers Ovulation and the formation of the Corpus Lutium Within the ovary Produces Progesterone Continues uterine lining thickening Fluctuations in Mood • Premenstrual syndrome - PMS • PMS is a combination of severe physical and psychological symptoms, such as depression and irritability, occurring just before menstruation 24 Fluctuations in Performance • Research on intellectual or athletic performance generally shows no fluctuations over the cycle • Research on academic performance, problem solving, memory, or creative thinking shows no fluctuations over the cycle 25 What Causes the Fluctuations in Mood • Biological factors – Fluctuations in levels of hormones • Environmental factors – Menstrual taboos and cultural expectations 26 What is Menopause? • 12 months of amenorrhea (no menses) • Average age 51 • Derived from the Greek words “men” (month) and “pausis” (cessation) • Primary ovarian function stops • Marks the permanent end of fertility Menopausal Symptoms • • • • • • • • • Hot flashes Sleep disturbances Vaginal dryness Mood changes Difficulty concentrating Memory impairment Bladder irritability/urgency Changes in balance Decreased interest in sex, possibly decreased response to sexual stimulation Other Causes to Consider • • • • • Thyroid disorders Pheochromocytoma Leukemia Cancer Infection References • http://www.ux1.eiu.edu/~cfjcd/Menstrual_Cy cle. • http://members.optushome.com.au/medstuff /Menstrual%20cycle.pdf • http://www.drugs.com/cg/menstruation.html 30