Scientifically, a man’s reproductive age starts from puberty till death. Which means, a man can reproduce throughout his life starting from puberty. Contrary to this, a woman’s reproductive age is much shorter. They can only reproduce for a period between their puberty and menopause. The phase-in between, when a woman is in her reproductive stage of life is also called the menstrual age. A menstrual cycle is the process of ovulation or egg production and menstruation in women. It is a natural change that regularly occurs in a female reproductive system, which also is the basis of pregnancy.
During this phase, a woman’s body goes through a variety of changes. The menstrual cycle ensures the production of oocytes and prepares the uterus for pregnancy. When an ovum is not fertilized in the absence of the sperm, the lining of the uterus sheds and leads to hemorrhage, called menstruation. The menstrual age starts from the age of 10 to 15 when a girl attains puberty and this beginning is known as menarche. The cessation of menstruation is called menopause which usually takes place at the age of 50.
The menstrual cycle begins with the first day of bleeding and the cycle repeats itself every 28 to 33 days depending on the individual menstrual cycle. Let’s quickly understand a female reproductive organ in short first before moving on to the menstrual cycle.
A Female Reproductive System Consists of the Following-
• A pair of ovaries- It releases the ovum or the egg.
• A uterus or womb- It’s where a fertilized egg gets implanted and the fetal development occurs.
• A pair of Fallopian Tubes- These tubes connect the ovaries to the uterus.
A girl is born with a pre-decided number of ovaries that she will produce in her reproductive stage. During puberty, various hormones trigger the production and release of eggs.
Phases of Menstruation Cycle
Each cycle of menstruation occurs in four different phases-
1. Menstrual Phase
It’s the phase when the uterus lining or the endometrial lining is shed off from the body. It’s marked as the day1 of periods which normally lasts for 3 to 7 days. The endometrial fluid is composed of the blood, cells from the lining of the uterus (endometrial cells) and mucus.
2. Follicular Phase
Followed by hormonal stimulation, the ovary produces around 5 to 20 follicles (tiny nodules or cysts), which bead on the surface. Each follicle consists of an immature egg. Out of these, only one follicle matures into an egg. Finally, a mature egg follicle releases an egg from one of the two ovaries. The follicular growth also stimulates the lining of the uterus to thicken in preparation for a possible pregnancy.
3. Ovulatory Phase
This is also known as the Mid-cycle phase. It is marked by the release of a mature egg from the surface of the ovary. Day 13-17 is mostly the period of ovulation. Various hormones trigger the ovulation and simultaneously release the egg into the fallopian tubes. The egg swiftly moves through the fallopian tubes towards the uterus. If fertilization occurs within 24 hours, the egg turns into an embryo. If not, it dies and disintegrates.
4. Luteal Phase
The ruptured follicle that had stayed behind on the surface of the ovary during the ovulatory phase starts to develop into a structure called corpus luteum. This layer releases hormones to thicken the uterine lining for any possible implantation of a fertilized egg. Corpus luteum is maintained if pregnancy establishes. If pregnancy doesn’t occur, it disintegrates. This usually occurs at 22-28 days. Another set of hormonal changes cause the uterine lining to fall away, thus causing menstruation. The next cycle starts with this.
Menstrual Cycle Diagram
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Hormonal Control of Menstrual Cycle
Hormones are chemical messengers in the body, directing the body what to do when. They are produced and released by endocrine organs. The menstrual cycle is also a process controlled by hormones in the female body. Some exclusive female hormones are released to bring about every cycle of menstruation. Varying levels of hormones- Estrogen, Progesterone, Luteinizing Hormone (LH), and Follicle Stimulating Hormone (FSH) direct different phases of the menstrual cycle.
It is released by the pituitary gland on signaling from the hypothalamus. It stimulates the ovary to produce egg follicles.
Rising levels of LH which are also prompted by the hypothalamus and released by the pituitary gland trigger the ovulation and lead to the release of the egg in fallopian tubes.
It is the hormone that prompts the growth of the uterine lining or the endometrial lining.
The corpus luteum releases some amounts of progesterone to maintain the thick lining of the uterus for a possible healthy pregnancy.
Thus, various female hormones do their part in keeping the menstrual cycle regular and making the ovaries release one egg every month for fertilization.
Menstruation is a biofeedback system. Each structure and gland involved are affected by the activity of others. And malfunctioning of any leads to an onset of menstrual problems and diseases. Various female hormones regulate the menstrual cycle along with leading some other chemical and physical changes in the female body.