Physiology of Human Reproduction: The Menstrual Cycle

Introduction

The menstrual cycle is a complex physiological process essential for female reproductive health. It is regulated by intricate hormonal interactions and involves cyclical changes in the endometrium.

Phases of the Menstrual Cycle

1. Follicular Phase

Starts on the first day of menstruation and continues until ovulation. Estrogen levels rise, stimulating endometrial proliferation.

2. Ovulation

Triggered by a surge in luteinizing hormone (LH), releasing a mature ovum from the ovarian follicle.

3. Luteal Phase

Post-ovulation phase where progesterone levels rise, stabilizing the endometrial lining for potential implantation.

4. Menstruation

If fertilization does not occur, progesterone levels drop, leading to the shedding of the endometrial lining.

Hormonal Control

• Estrogen: Stimulates endometrial growth.
• Progesterone: Prepares the uterus for potential pregnancy.
• Luteinizing Hormone (LH): Induces ovulation.
• Follicle-Stimulating Hormone (FSH): Stimulates follicle development.

Endometrial Changes

The endometrium undergoes cyclical changes, responding to hormonal fluctuations:

• Proliferative phase: Growth under estrogen influence.
• Secretory phase: Maturation under progesterone influence.
• Menstrual phase: Shedding of the lining if pregnancy does not occur.

Conclusion

Understanding the menstrual cycle is crucial for reproductive health management. Awareness of hormonal and endometrial changes aids in diagnosing and treating menstrual disorders.