THE MENSTRUAL CYCLE

Summary

In this 9th-grade science lesson, Mrs. Suryati explains the human menstrual cycle, detailing its phases: the menstrual phase, proliferative phase, and secretory phase. The lesson highlights menstruation as the shedding of the uterine lining when an egg is not fertilized, typically occurring every 28 days, though it can vary among women. Key hormones like FSH, estrogen, and progesterone play vital roles in regulating these phases, preparing the uterus for potential pregnancy. If fertilization does not occur, the cycle culminates in menstruation, characterized by the discharge of blood, mucus, and epithelial cells. This informative session aims to enhance students' understanding of human reproductive biology.

Takeaways

• 😀 menstruation is the monthly discharge of blood, mucus, and epithelial cells from the uterus when an egg is not fertilized.
• 😀 the menstrual cycle typically lasts about 28 days but can vary from 18 to 40 days depending on the individual.
• 😀 the cycle consists of three main phases: the menstrual phase, proliferative phase, and secretory phase.
• 😀 during the menstrual phase, the uterine lining sheds, resulting in menstruation that lasts several days.
• 😀 the proliferative phase involves the production of estrogen and progesterone, which thickens the uterine wall in preparation for a potential pregnancy.
• 😀 FSH (Follicle-Stimulating Hormone) stimulates the development of follicles in the ovaries.
• 😀 LH (Luteinizing Hormone) triggers ovulation, leading to the release of a mature egg from the follicle.
• 😀 in the secretory phase, if fertilization does not occur, the corpus luteum degenerates, causing hormone levels to drop.
• 😀 low levels of estrogen and progesterone lead to menstruation, indicating that the unfertilized egg and uterine lining are expelled.
• 😀 if fertilization occurs, it results in pregnancy; otherwise, menstruation is a natural process marking the end of the cycle.

Q & A

What is menstruation?

Menstruation is the discharge of blood, mucus, and epithelial cells from the uterine wall through the vagina, typically occurring once a month in females who have entered puberty.

How long does a typical menstrual cycle last?

A typical menstrual cycle lasts about 28 days, but it can vary; some women may have cycles as short as 18 days or as long as 40 days.

What are the three phases of the menstrual cycle?

The three phases of the menstrual cycle are the menstrual phase, the proliferative phase, and the secretory phase.

What happens during the menstrual phase?

During the menstrual phase, the uterine lining sheds, resulting in the discharge of blood, mucus, and epithelial cells.

What role does the FSH hormone play during the menstrual cycle?

The FSH hormone triggers the development of follicles in the ovaries during the menstrual phase.

What occurs in the proliferative phase?

In the proliferative phase, estrogen and progesterone are produced by developing follicles, leading to the thickening of the uterine wall in preparation for a possible embryo.

What triggers ovulation?

The increase in LH hormone levels during the menstrual cycle triggers ovulation, which is the release of an egg from mature follicles.

What happens during the secretory phase?

During the secretory phase, the follicle that released the egg transforms into the corpus luteum, which produces hormones. If the egg is not fertilized, hormone levels drop, leading to menstruation.

What are the consequences if an egg is fertilized?

If the egg is fertilized by a sperm cell, it can result in pregnancy, as the thickened uterine wall is prepared to support the embryo.

What is the significance of menstruation for women?

Menstruation signifies that a woman has an egg available each month. If the egg is not fertilized, it is expelled from the body along with the uterine lining.