Question

(c) In menstrual cycle which reproductive organs undergo changes? 
 

Hint:

The ovary and uterus work closely during the menstrual cycle. The ovary releases eggs, while the uterus prepares its lining (endometrium) for a potential pregnancy. If no fertilization occurs, the endometrial lining sheds during menstruation, and the cycle starts again!

Answer 1

Ovary and uterus (endometrium).
The ovary and uterus play crucial roles in the menstrual cycle, fertility, and pregnancy. Here's an explanation of each structure and its function:
- Ovary: The ovaries are two small, almond-shaped organs located on either side of the uterus. Their primary function is to produce eggs (oocytes) and secrete hormones such as estrogen and progesterone.
- Follicular Phase: During the follicular phase of the cycle, which begins at menstruation and ends at ovulation, several follicles in the ovaries begin to mature. One of these follicles becomes dominant and prepares to release an egg during ovulation.
- Ovulation: At around day 14 of a typical 28-day cycle, a mature egg is released from the dominant follicle and enters the fallopian tube, ready for possible fertilization. The ovary also produces estrogen, which helps thicken the uterine lining in preparation for implantation.
- Luteal Phase: After ovulation, the ruptured follicle transforms into the corpus luteum, which produces progesterone. This hormone supports the endometrial lining for a potential pregnancy. If fertilization does not occur, the corpus luteum degenerates, leading to a drop in progesterone levels and the start of menstruation.
- Uterus (Endometrium): The uterus is a hollow, muscular organ where a fertilized egg implants and develops during pregnancy. The inner lining of the uterus, called the endometrium, undergoes cyclical changes in response to hormonal signals from the ovaries.
- Menstrual Phase: If pregnancy does not occur, the levels of estrogen and progesterone drop, leading to the shedding of the endometrial lining. This results in menstruation, or the period.
- Proliferative Phase: Following menstruation, the endometrium thickens under the influence of estrogen, preparing for potential embryo implantation.
- Secretory Phase: After ovulation, progesterone from the corpus luteum further thickens the endometrial lining, making it more receptive to an embryo. If fertilization occurs, the embryo implants in the endometrium. If not, the endometrial lining breaks down and is shed during the next menstrual cycle.
In summary, the ovaries and the uterus work together to regulate the menstrual cycle, facilitate fertilization, and support pregnancy when it occurs.