Menstrual Cycle Explained | MCAT Biology скачать в хорошем качестве

Menstrual Cycle Explained | MCAT Biology

This video talks about The menstrual cycle is an intricately regulated sequence of physiological changes that occur in the female reproductive system to prepare for potential pregnancy. The cycle averages 28 days but can vary between 21 and 35 days. It is divided into four phases: menstrual, follicular, ovulation, and luteal. The cycle begins with the menstrual phase (days 1-5), characterized by the shedding of the endometrial lining if fertilization has not occurred, resulting in menstrual bleeding. Concurrently, the follicular phase (days 1-13) is initiated, where the anterior pituitary gland secretes follicle-stimulating hormone (FSH), promoting the growth of ovarian follicles. As these follicles mature, they produce estrogen, which facilitates the regeneration of the endometrial lining. Ovulation (around day 14) is triggered by a surge in luteinizing hormone (LH), causing the release of a mature oocyte from the dominant follicle. The oocyte then travels through the fallopian tube, where fertilization by sperm may occur. Following ovulation, the luteal phase (days 15-28) ensues, during which the ruptured follicle transforms into the corpus luteum. The corpus luteum secretes progesterone and, to a lesser extent, estrogen, which further thicken and maintain the endometrial lining in preparation for a potential implantation of a fertilized egg. If fertilization and implantation do not occur, the corpus luteum degenerates, leading to a decline in progesterone and estrogen levels. This hormonal decrease causes the endometrial lining to break down and shed, marking the onset of a new menstrual cycle. This video will help you learn the basics and foundational knowledge needed to ace your exams! Timestamps 0:00 Intro 0:23 Intro to the menstrual cycle 1:05 Learning about the menstrual cycle 1:52 Hypothalamus Pituitary Gonadal Axis (HPG Axis) 2:41 Hormones of the menstrual cycle 2:42 Gonadotropin-releasing hormone (GnRH) 2:54 Follicular-stimulating hormone (FSH) 3:06 Leutanizing hormone (LH) 3:26 Estrogen 3:36 Progesterone 3:53 The menstrual phase 4:21 Hormones during the menstrual phase 5:53 The Follicular phase 6:22 Hormones during the follicular phase 8:38 Ovulation 9:37 Hormones during ovulation 10:47 The Luteal phase 11:00 Hormones during the Luteal phase 12:30 Interactions between the menstrual cycle and the HPG axis 15:36 Outro Thanks for watching! I hope this was helpful for you. ------------------------------------------------------------------------------------------------------------ **Subscribe for more free lessons:    / @themedtutor**   ------------------------------------------------------------------------------------------------------------ Check Out Some of Our Other Lessons Biochemistry Playlist:    • Biochemistry   Chemistry Playlist    • Chemistry   Anatomy Playlist    • Anatomy   Cell Biology Playlist    • Cell Biology   Amino Acids Playlist    • Amino Acids | MCAT Biochemistry