Female Reproductive Cycle | Menstrual Cycle

Summary

This video explains the female reproductive cycle, focusing on the menstrual phases. It details the roles of estrogen and progesterone in the cycle, including menstruation (shedding of the endometrial lining), the proliferative phase (regeneration of the endometrium and arteries), and the secretory phase (preparing the uterus for a potential pregnancy). The video covers the hormonal changes, uterine anatomy, and how these hormones affect the uterine lining, cervical mucus, and blood flow. It also discusses what happens if fertilization occurs, as well as the effects if it doesn’t, including the formation of the corpus albicans.

Takeaways

• 🔄 The menstrual cycle has three phases: menstruation, proliferative, and secretory.
• 🩸 Menstruation involves shedding the stratum functionalis, a layer of the endometrium, along with blood from the spiral arteries.
• 🌱 The proliferative phase, days 6-14, regenerates the stratum functionalis and spiral arteries, driven by estrogen.
• 🧬 Estrogen also leads to the creation of uterine glands and thin cervical mucus, aiding sperm movement toward the egg.
• 🚼 Around day 14, ovulation occurs, releasing an oocyte for potential fertilization.
• 🧪 The secretory phase (days 15-28) is driven by progesterone, which thickens the stratum functionalis and enhances blood supply via spiral arteries.
• 🥣 Progesterone stimulates uterine glands to secrete a nutrient-rich fluid to nourish a potential embryo.
• 🛑 If fertilization occurs, human chorionic gonadotropin (hCG) from the embryo maintains progesterone production.
• ⚠️ If no fertilization occurs, the corpus luteum dies, progesterone drops, spiral arteries weaken, and menstruation begins again.
• 🧫 The cycle restarts if no embryo forms, and the corpus luteum turns into scar tissue called the corpus albicans.

Q & A

What are the three phases of the menstrual cycle?

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

What happens during the menstruation phase?

During the menstruation phase, the stratum functionalis (the upper layer of the endometrium) is shed, resulting in blood loss from the spiral and coiled arteries.

What are the two layers of the endometrium and their functions?

The two layers of the endometrium are the stratum functionalis, which is shed during menstruation, and the stratum basalis, which remains and regenerates the stratum functionalis during the next cycle.

What role does estrogen play in the proliferative phase?

During the proliferative phase, estrogen helps regenerate the stratum functionalis, stimulates the growth of spiral and coiled arteries (angiogenesis), and starts the formation of uterine glands.

Why is thin cervical mucus important during the proliferative phase?

Thin cervical mucus is important because it allows sperm to pass more easily through the cervix, facilitating fertilization during ovulation.

What happens during the secretory phase?

In the secretory phase, progesterone thickens the stratum functionalis, promotes the growth of spiral and coiled arteries, stimulates uterine glands to produce nutrient-rich fluids, and forms a thick cervical mucus plug to protect the uterus.

What hormone drives the secretory phase, and where is it produced?

Progesterone drives the secretory phase, and it is produced by the corpus luteum in the ovary.

What happens if fertilization does not occur by the end of the secretory phase?

If fertilization does not occur, progesterone levels drop, the spiral arteries spasm and rupture, leading to the shedding of the stratum functionalis, which results in menstruation.

What is the corpus luteum, and what happens to it if fertilization does not occur?

The corpus luteum is a hormone-producing structure formed from the Graafian follicle after ovulation. If fertilization does not occur, it degenerates into the corpus albicans, a scar-like tissue, and stops producing progesterone.

What is the function of human chorionic gonadotropin (hCG) if fertilization occurs?

If fertilization occurs, the embryo releases hCG, which signals the corpus luteum to continue producing progesterone until the placenta is developed around the 12th week of pregnancy.