GRADE 10 SCIENCE QUARTER 3 WEEK 2 | MENSTRUAL CYCLE

Summary

In this educational lesson, the science of the menstrual cycle is explored in depth. The video breaks down the four phases of the cycle—menstrual, follicular, ovulation, and luteal—while also explaining the roles of hormones like estrogen, progesterone, and luteinizing hormone. The script covers the feedback mechanisms that regulate these hormones through positive and negative feedback loops, highlighting the cycle’s physiological processes. It also touches on common symptoms and questions related to menstruation, such as mood swings and bowel changes. The lesson aims to provide students with a clear understanding of the menstrual cycle’s complexity.

Takeaways

• 😀 The menstrual cycle is a monthly cycle that involves changes in the female reproductive system, lasting around 28 days on average.
• 😀 The menstrual cycle consists of four phases: the menstrual phase, follicular phase, ovulation phase, and luteal phase.
• 😀 The menstrual phase begins when an egg is not fertilized, leading to the shedding of the uterine lining as menstrual fluid.
• 😀 The follicular phase starts on the first day of menstruation and lasts until about the third day of the cycle. It involves the maturation of an egg and the thickening of the endometrium.
• 😀 Ovulation occurs around day 14 of a typical 28-day cycle, when a mature egg is released from the ovary and travels through the fallopian tube toward the uterus.
• 😀 The luteal phase starts on day 15 and lasts until the end of the cycle. If the egg isn't fertilized, the endometrium disintegrates, and menstruation occurs.
• 😀 Hormones such as estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) regulate the menstrual cycle through positive and negative feedback mechanisms.
• 😀 In positive feedback, rising hormone levels increase hormone production, whereas negative feedback decreases hormone production when levels rise.
• 😀 Estrogen levels stimulate the production of LH, which triggers ovulation. High levels of progesterone, in turn, inhibit further LH production.
• 😀 During menstruation, abdominal cramps are caused by uterine contractions that help expel menstrual fluid from the body.
• 😀 Hormonal changes throughout the menstrual cycle can influence mood and behavior, leading to symptoms such as irritability, sadness, and increased crying, especially in the days leading to and during menstruation.

Q & A

What is the menstrual cycle?

The menstrual cycle is the monthly cycle of changes that happens in the female reproductive system. It lasts roughly 28 days and includes four main phases: the menstrual phase, follicular phase, ovulation phase, and luteal phase.

What happens during the menstrual phase?

The menstrual phase is the first stage of the menstrual cycle. It starts when an egg from the previous cycle is not fertilized. The uterus sheds its inner lining of soft tissues and blood vessels, resulting in menstruation or the period.

How long does the menstrual phase last?

The menstrual phase typically lasts for about 3 to 7 days, though this can vary from person to person.

What is the follicular phase, and when does it occur?

The follicular phase begins on the first day of menstruation and lasts until around day 13 of the cycle. During this phase, the egg cells in the ovaries begin to mature, and the uterus starts developing the endometrium in preparation for a potential pregnancy.

What triggers ovulation, and what happens during it?

Ovulation is triggered when estrogen levels rise, signaling the pituitary gland to release luteinizing hormone (LH). LH then stimulates the ovary to release a mature egg. This occurs around day 14 of a typical 28-day cycle.

How long does the egg remain viable after ovulation?

The egg remains viable for about 24 hours after ovulation. If it is not fertilized by sperm within this time, it will disintegrate or dissolve.

What happens during the luteal phase?

The luteal phase begins on day 15 of the menstrual cycle and lasts until the end of the cycle. During this phase, the egg cell released during ovulation either gets fertilized and implanted in the uterus or, if fertilization does not occur, the endometrium disintegrates, leading to menstruation.

What is the role of hormones like estrogen and progesterone in the menstrual cycle?

Estrogen and progesterone play crucial roles in regulating the menstrual cycle. Estrogen helps build the uterine lining during the follicular phase, while progesterone supports the maintenance of the endometrium during the luteal phase. If pregnancy doesn't occur, both hormone levels drop, initiating menstruation.

What is negative feedback in the context of hormone regulation during the menstrual cycle?

Negative feedback occurs when rising levels of hormones, like estrogen or progesterone, signal the hypothalamus and pituitary gland to decrease the production of those hormones. For example, high levels of estrogen inhibit the further production of follicle-stimulating hormone (FSH).

Can hormonal changes affect mood and behavior during the menstrual cycle?

Yes, hormonal changes throughout the menstrual cycle can significantly impact mood and behavior. For instance, many people experience mood swings, irritability, or increased emotional sensitivity, especially in the days leading up to menstruation (PMS).

Why do some people experience more bowel movements or diarrhea during their period?

Hormones like prostaglandins, released just before menstruation, can cause the uterus to contract. These contractions also affect the intestines, leading to more frequent bowel movements or diarrhea due to muscle contractions and reduced water absorption.

What is the average amount of blood loss during menstruation, and is it normal to experience cramps?

Normal menstrual blood loss ranges from 10 to 80 milliliters. Menstrual cramps, which are caused by the contraction of the uterine muscles to expel the menstrual fluid, are also common and can vary in intensity.