Describe in general terms the events that take place in each phase of the menstrual cycle (e.g., flow phase, follicular phase, ovulation, luteal phase).
Describe in general terms the events that take place in each phase of the menstrual cycle (e.g., flow phase, follicular phase, ovulation, luteal phase).
Menstruation can be described as a cyclic process during which the uterine lining and unfertilized egg sloughs off in response to multiple hormones released by the pituitary, hypothalamus ovaries of a female. The menstrual cycle is further divided into four subphases flow phase, follicular phase, ovulation, and luteal phase.
The phases of the menstrual cycle are described below
(a)Flow phase or menstrual phase: It is represented by the initial phase of menstruation during which the thickened endometrium prepared for implantation sheds off in the absence of pregnancy. During the menstrual phase, the uterus's unfertilized blood, mucus, and tissues shed off through the vagina. This phase continues for 5 days.
(b) Follicular phase: During the follicular phase, the hypothalamus stimulates the pituitary gland to release a follicle-stimulating hormone, which in turn stimulates the ovaries to produce follicles containing an immature egg. On maturation of the egg, each of the follicles releases an egg from one of the ovaries. On the other side, the lining of the uterus starts to thicken for preparing it for pregnancy by the action of estrogen.
(c) Ovulatory phase or ovulation: The estrogen hormones' levels keep on increasing, which triggers the pituitary gland to release LH hormone. The LH hormone initiates the process of ovulation. Ovulation can be defined as a process during which a mature egg is released from one of the ovaries and travels toward the fallopian tube for fertilization.
(d) Luteal Phase: After a mature egg is released from a follicle, the degenerated follicle is regenerated into corpus luteum, releasing hormones such as progesterone and estrogen. These pregnancy hormones are responsible for maintaining the lining of the uterus for pregnancy. If the egg's fertilization does not occur, the corpus luteum gets degenerated, decreasing the levels of pregnancy hormones, which leads to shedding of uterine lining and the cycle is repeated.
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