Menstrual cycle is a part of reproductive cycle in female. This cycle involves four phases from formulationn of ovum or egg cell to release unwanted ovum cell. The first menstruation begins at puberty which is known as menarche. Puberty starts in between 10-15 years of age. In females, menstruation is repeated at an interval of about 28-35 days and this cycle from one to another is known as menstrual cycle. The regular menstrual cycle is essential for healthy reproductive health of a female.
- Many hormones have important roles to regulate menstrual cycle.
- The menses or menstruation period is the intiative phase which lasts up to 3-7 days.
- The duration of different phases in menstruation cycle varies among the females.
- Factors like food, environment, physical and mental health etc affects the regularity of menstrual phases.
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Key terms: Menstrual cycle, Phases of menstrual cycle, Menstruation, Egg, Fertilization, Ovulation, Bleeding
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What is menstruation?
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Every month the uterus expands to be ready for a fertilized egg. If it doesn’t receive any fertilized egg to initiate a pregnancy, the uterus excretes its endometrial lining. Hence a woman experiences bleeding every month.
Menstrual cycle
The menstrual cycle is counted from Day 1 of the bleeding till the Day 1 of the next month’s bleeding. The cycle is usually of 28-35 days; however, it does differ individual to individual. A female bleeds between 3-7 days. The 4 phases of menstrual cycle are as follows.
Menstrual phase
It is the phase when the uterus lining sheds. It is called the day 1 of the menstruation which lasts 3-7 days. The endometrial fluid which sheds consist of blood, lining of cell and mucus.
Follicular phase
In this phase, one follicle matures into an egg (ovum) and releases from one of the two ovaries. This stimulates the lining of the uterus to thicken and develop a protective wall for fetus if preganancy takes place.
Ovulatory phase
This is the mid cycle phase. Day 13-17 is marked as the ovulation phase. In this phase, hormones trigger the ovulation and at the same time releases the egg into the fallopian tubes. The egg moves to the uterus and waits for the fertilization, if fertilization does not occur, then it dies and gets released as menstrual bleeding.
Luteal phase
This the last phase wherein the fate of corpus luteum is decided. If fertilization happens, then pregnancy starts. If not, then it prepares for the next menstrual cycle.
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Menstrual Hormones
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The chemical messengers in the body are called hormones which are released by the endocrine glands. These hormones are responsible for the changes that occur in the body. In every menstrual cycle, these hormones are released and regulate the functions of the different phases of menstrual cycle. The hormonal levels vary in every female. The 4 menstruation hormones are:
FSH
Follicle Stimulating Hormones, is released by the pituitary gland when gets signals from hypothalamus. It instructs the ovary to produce egg follicles.
LH
Luteinizing Hormones, it is also released by pituitary gland on signalling from hypothalamus which triggers the ovulation and helps to release the egg to the fallopian tube.
Oestrogen
It promotes the growth of the uterine lining for upcoming pregnancy.
Progesterone
The corpus luteum releases some amount of these hormones to maintain the thickening of the uterus for the possible pregnancy.
Menstrual hormones
- Each hormone plays an important role for a healthy menstrual cycle.
- Malfunction of any of the hormones may lead to menstrual problems and may cause diseases.
- These hormones work in sync to make sure that the menstrual cycle has been regulated.
- They also play an important role for physical and chemical changes in the female body.
- Typical changes during menstrual cycle are some females experience pain during the first two days, whereas some do not experience it.
- However, some females experience this pain before or after the cycle.
- Some experience heavy blood flow while some have scanty blood flow.
- Due to hormonal changes, females can experience mood swings, these are termed as PMS(Premenstrual syndrome).
- Females can experience bloating and increase in water weight.
- Furthermore, breast becomes tender, acne on the face, cramps happen in the stomach, back or legs etc are the physical changes.
- However, these cramps go away after one- two days of menstrual period.
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Things to Remember
- Menstrual cycle is a part of the female reproductive system.
- A female experiences menstruation every month but not during the pregnancy.
- The phases of menstrual cycle include menstrual phase, follicular phase, ovulation and luteal phase.
- The hormones that regulate the menstrual cycle are FSH, LH, Oestrogen and Progesterone.
- Menstrual cycle is usually of 25 to 28 days.
- The regularity of menstruation varies among the females.
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Sample Questions
Ques. What is PMS? Does this happen to every female? (1 mark)
Ans. PMS is premenstrual syndrome; every 3rd female experiences it. These symptoms are caused by hormonal changes of the cycle.
Ques. What are the common premenstrual symptoms? (1 mark)
Ans. Depressive mood, angry outburst, irritability, anxiety, confusion, breast tenderness, abdominal bloating, headache.
Ques. How long is the menstrual period? (1 mark)
Ans. The time from the first sign of blood to the last is usually in the 3-to-5-day range.
Ques. What are the symptoms of hormonal imbalance? (1 mark)
Ans. There can be imbalance in oestrogen or progesterone, which may lead to irregular or heavy bleeding. The gap between the period may change.
Ques. Write about the 4 phases of the menstrual cycle. (5 marks)
Ans.The menstrual cycle is divided into 4 phases.
- Menstrual phase- It is the first day of bleeding that lasts up to 3 to 7 days. This is the start of the menstrual cycle. If a female does not get her egg fertilized, the uterus lining starts to degenerate and it gets secreted outside the body.
- Follicular phase- One follicle matures into an ovum and releases from one of the two ovaries.
- Ovulatory phase: Day 13-17 is the ovulation phase. In this phase, hormones trigger the release of the ovum into the fallopian tubes. The ovum moves to the uterus and waits for the fertilization.
- Luteal phase: This is the last phase. If fertilization happens, the pregnancy will be initiated. If the ovum is not fertilized during this phase, it will initiate the next menstrual cycle.
Ques. Why do females experience bleeding every month? (2 marks)
Ans. In the female body, the ovum is released every month from any one of the two ovaries. This ovum will move to the fallopian tube to get fertilized by the sperm cell. However, when fertilization does not occur, the ovum will die and the uterus lining that is composed of blood and mucus will start dissociating. This endometrial lining will be excreted out the body as bleeding. This bleeding phase is called the menstrual phase.
Ques. What is the time period for the ovulation phase? (1 mark)
Ans.The ovulation phase starts from the 13th day and lasts up to the 17th day.
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