In this class we explain the hormonal regulation of ovarian cycle by the hypothalamic-pituitary-gonad. It also explains the changes undergone by the endometrium throughout the cycle and development.
Interactive images embedded in the text will help you gain a better understanding of it. Each image is accompanied by an interactive explanation of the cycle characteristics, as well as the characteristics of the image itself.
The ovarian cycle is regulated by the interaction of hormones produced by the hypothalamic-pituitary-gonad. There are five main hormones involved in this process: GnRH, FSH, LH, estradiol and progesterone.
The cycle is divided into three phases: follicular, ovulation, luteal phase.
Describe the cycle, day 1 designating the first day of bleeding. Throughout the cycle will produce a series of changes in levels of gonadotropins and ovarian hormones 1 . Each hormone has a different function.
- The FSH is the hormone that makes the recruitment and growth of ovarian follicles and the willLesson of the dominant follicle. Acts on the granulosa cells and has a half life of 4 hours.
- The LH acts on interstitial cells and stromal way that induces the production of steroids and triggers ovulation. It has a half-hour half-life.
The steroids synthesized by the action of gonadotropins are estradiol and progesterone. Occur at the level of hair and body lúteo. 3
During the first week of the cycle begins recruitment of the cohort of follicles. FSH in the first week gradually increases, the follicles are growing at the same time that increase the number of receptors on the granulosa to this hormone, the same is true for the LH receptor level teca. 2 cells The follicles produce estradiol at this time in small quantities.
In the second week all of the cohort follicles continue to grow, the FSH receptors of granulosa increase so that the granulosa is transforming androgens into estradiol resulting in a significant increase this. This increase produces a negative feedback onFSH decreased significantly. Thus the dominant follicle is selected. The remaining follicles will degenerate by a process called atresia.
After selecting the dominant follicle, the concentration of Estradiol is increasing, so that is a peak 72 hours before the ovulación. 1 This high concentration of estradiol produces a positive feed back which leads to the occurrence of increased production of FSH and LH leading to a peak of both hormones.
36 hours after the LH peak occurs ruptured Graafian follicle releases the oocyte and resulting in ovulation.
Produced once ovulation the granulosa cells are arranged to form a new gland the corpus luteum. The corpus luteum will 3 different ways depending on whether or not fertilization occurs.
While the stages are produced ovary, the endometrium undergoes cyclic changes in thickness and texture, related to levels of estrogen and progesterone. 5
Cyclical changes of the endometrium during the menstrual cycle result in several phases: proliferative, secretory andmenstrual. These stages are developed continuously, so that no sudden change between ellas 6 . Explain in detail each of these phases helping us Wesapiens images.
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