Menstrual Cycle Overview

Questions and Answers

What is primarily produced by the corpus luteum after ovulation?

Estrogen

Progesterone (correct)

Luteinizing hormone

Testosterone

What happens to the levels of estrogen after the follicle transforms into the corpus luteum?

Estrogen levels increase significantly

Estrogen levels remain constant

Estrogen levels fluctuate unpredictably

Estrogen levels decrease greatly (correct)

What structure forms from the remnants of the follicle after ovulation?

Endometrium

Corpus luteum (correct)

Ovarian stroma

Graafian follicle

What is the role of progesterone after ovulation?

To prepare the uterine lining for implantation Signup and view all the answers

What is the name of the hormone that is primarily responsible for inducing the follicle to become the corpus luteum?

Luteinizing hormone (LH) Signup and view all the answers

What phase follows ovulation in the menstrual cycle?

Luteal phase Signup and view all the answers

What is the egg called at the stage of implantation?

Blastocyst Signup and view all the answers

Which hormone is involved in decreasing after ovulation?

Estrogen Signup and view all the answers

What role does progesterone play during the secretory phase of the menstrual cycle?

Stimulates the uterine lining to prepare for implantation Signup and view all the answers

Which structure produces a large amount of progesterone during the luteal phase?

Corpus luteum Signup and view all the answers

What effect does progesterone have on uterine muscle contractility?

Reduces it to prevent embryo expulsion Signup and view all the answers

What happens when the corpus luteum begins to atrophy?

Menstruation is triggered Signup and view all the answers

What hormone actively inhibits FSH release from the anterior pituitary?

Inhibin Signup and view all the answers

What physiological change signals the beginning of menstruation?

Decreased levels of progesterone and estrogen Signup and view all the answers

What is the primary function of spiral arteries in the endometrium?

To facilitate nutrient exchange for the embryo Signup and view all the answers

What effect does negative feedback from progesterone and estrogen have on FSH and LH production?

Inhibits their production Signup and view all the answers

What hormone is produced by the embryo that helps maintain the corpus luteum during pregnancy?

Human chorionic gonadotropin Signup and view all the answers

What is a common sign that pregnancy has not occurred?

Menstruation Signup and view all the answers

How long does menstruation typically last?

2 to 7 days Signup and view all the answers

What happens to the corpus luteum if pregnancy does not occur?

It withers away and the cycle repeats Signup and view all the answers

For how long does the corpus luteum primarily produce progesterone during pregnancy?

2 to 3 months Signup and view all the answers

Why does menstruation not occur during pregnancy?

The corpus luteum is maintained and continues hormone release Signup and view all the answers

What role does the placenta play in pregnancy in relation to progesterone?

It takes over as the major producer of progesterone after a few months Signup and view all the answers

What effect does HCG have on the corpus luteum?

It rescues the corpus luteum from atrophy Signup and view all the answers

Which hormone is structurally similar to HCG and necessary for corpus luteum survival?

Luteinizing hormone Signup and view all the answers

How do pregnancy tests typically work?

By checking for HCG presence in blood or urine Signup and view all the answers

Study Notes

Follicular and Luteal Phases

The follicular phase focuses on stimulating growth of ovarian follicles, leading to ovulation.
Key hormones involved in this phase include FSH (Follicle Stimulating Hormone), LH (Luteinizing Hormone), and estrogen.
The luteal phase occurs post-ovulation; the remaining follicle transforms into the corpus luteum, a yellow structure.

Corpus Luteum and Hormonal Changes

After ovulation, LH levels rise significantly, facilitating the formation of the corpus luteum.
The corpus luteum produces progesterone in high quantities, although it also secretes some estrogen.
Progesterone is essential for preparing the uterine lining (endometrium) for potential implantation of a fertilized egg.

Role of Progesterone

Progesterone enhances blood flow to the endometrium through the development of spiral arteries, ensuring nutrient access for the embryo.
It stimulates uterine secretions from glands that nourish the embryo.
Progesterone decreases uterine muscle contractility to protect the embryo from expulsion during early development.

Feedback Mechanisms

The corpus luteum's production of progesterone and estrogen suppresses FSH and LH secretion via negative feedback.
Inhibin, produced by the corpus luteum, further inhibits FSH release.

Luteal Phase End and Menstruation

When the corpus luteum atrophies due to decreased FSH and LH levels, progesterone and estrogen levels also fall.
This drop triggers menstruation and shedding of the endometrial lining, marking the end of the luteal phase and the beginning of a new follicular phase.
Average blood loss during menstruation is around 40 milliliters over two to seven days.

Pregnancy Implications

If fertilization occurs, the embryo produces human chorionic gonadotropin (HCG), which mimics LH and sustains the corpus luteum.
The corpus luteum continues to release estrogen and progesterone, maintaining the endometrial lining to support the pregnancy.
Most pregnancy tests detect HCG levels to confirm pregnancy.

Transition to Placenta

The corpus luteum is the primary source of progesterone for the first two to three months of pregnancy.
After this period, the placenta takes over progesterone production, ensuring continued support for the developing fetus.

Summary of Outcomes

If no pregnancy occurs, the corpus luteum deteriorates, restarting the reproductive cycle approximately every 28 days.
If pregnancy occurs, the corpus luteum is preserved, preventing menstruation and allowing for the continued maintenance of the endometrial lining.

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Description

Explore the phases of the menstrual cycle, focusing on the follicular and luteal phases. Learn how hormonal changes, including FSH, LH, and estrogen, regulate ovarian function and ovulation. This quiz is perfect for understanding female reproductive biology.