\n1. Menstrual phase – The menstrual cycle begins with the menstrual step when menstrual flow occurs and lasts for 3-5 days. Menstrual flow is due to the breakdown of the endometrial lining of the uterus and its blood vessels due to a decline in progesterone and estrogen level. Menstruation occurs only if the fertilization is absent. The absence of menstruation may be an indicator of pregnancy. However, it could also be due to stress, hormonal disorder, and anemia.
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\n2. Follicular or proliferative phase – The follicular phase extends from the 5th day of the cycle until ovulation. During this period, the ovary's primary follicle grows to become a fully matured Graafian follicle, and simultaneously, the uterine wall regenerates through proliferation. These changes in the ovary and the uterus are induced by the secretion of gonadotropins, which increase gradually during the follicular phase. It stimulates follicular development and secretion of estrogen by the follicle cells. \n3. Ovulatory phase - Both gonadotropins, LH and FSH, attain peak levels in the middle of the cycle (about the 14th day). Maximum secretion of LH around the 13th or 14th day called LH surge induces the rupture of the Graafian follicle and the release of the ovum (secondary oocyte) from the ovary wall into the peritoneal cavity. This process is called ovulation. \n4. Luteal or secretory phase - During the luteal phase, the Graafian follicle's remaining part is transformed into a temporary endocrine gland called the corpus luteum. This gland secretes a large amount of progesterone, which is essential for the maintenance of the endometrium.
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\n"},"comment":{"@type":"Comment","text":"The physiological cycle has a preovulatory and post-ovulatory phase in the body of a female."},"encodingFormat":"text/markdown","learningResourceType":"Practice problem","suggestedAnswer":[],"text":"Explain the various phases of the menstrual cycle."},"name":"Quiz on Human Reproduction","typicalAgeRange":"10-17","url":"https://www.embibe.com/questions/Explain-the-various-phases-of-the-menstrual-cycle./EM5472900"}
Tamil Nadu Board Solutions for Exercise 1: Evaluation
Author:Tamil Nadu Board
Tamil Nadu Board Biology-Zoology Solutions for Exercise - Tamil Nadu Board Solutions for Exercise 1: Evaluation
Attempt the free practice questions from Exercise 1: Evaluation with hints and solutions to strengthen your understanding. Biology Zoology Standard 12 solutions are prepared by Experienced Embibe Experts.
Questions from Tamil Nadu Board Solutions for Exercise 1: Evaluation with Hints & Solutions
The following is the illustration of the sequence of ovarian events (a-i) in a human female. Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.