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Questions and Answers
What is the name of the hormone that is produced by the pituitary gland and stimulates egg production?
What is the name of the hormone that is produced by the pituitary gland and stimulates egg production?
FSH
What is the average length of a menstrual cycle?
What is the average length of a menstrual cycle?
28 days
What is the name of the structure that forms when a ruptured follicle fills with blood?
What is the name of the structure that forms when a ruptured follicle fills with blood?
Which of the following is NOT a phase of the ovarian cycle?
Which of the following is NOT a phase of the ovarian cycle?
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Which phase of the uterine cycle is characterized by the thickening of the uterine lining?
Which phase of the uterine cycle is characterized by the thickening of the uterine lining?
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The corpus luteum secretes estrogen and progesterone.
The corpus luteum secretes estrogen and progesterone.
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What is the main function of the hormone progesterone?
What is the main function of the hormone progesterone?
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What is the condition when a woman experiences painful menstruation due to the accumulation of prostaglandins in the uterus?
What is the condition when a woman experiences painful menstruation due to the accumulation of prostaglandins in the uterus?
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Which of these is NOT an indicator of ovulation?
Which of these is NOT an indicator of ovulation?
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The human chorionic gonadotropin (hCG) is produced by the embryo during pregnancy.
The human chorionic gonadotropin (hCG) is produced by the embryo during pregnancy.
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Study Notes
Menstruation Overview
- Menstruation is a cyclical process where the female reproductive system ripens and releases one mature egg
- The average cycle length is approximately 28 days, but it can range from 21 to 40 days.
- Menstruation involves the shedding of the endometrium, which then bleeds due to hormone fluctuations.
Physiology of the Female Reproductive System
- The hypothalamic-pituitary-ovarian axis controls the female reproductive system.
- GnRH from the hypothalamus stimulates the pituitary gland to release FSH and LH.
- FSH stimulates egg production in the ovaries
- LH also directs the production of progesterone in the ovaries
- Progesterone maintains the growth of the endometrium.
Physiological Stages
- Neonatal period: Birth to 4 weeks
- Childhood: 4 weeks to 12 years
- Puberty: 12 years to 18 years
- Sexual maturation: 18 years to 50 years
- Perimenopause: Decline in ovarian function (40 years to 1 year post-menopause)
The Menstrual Cycle
- The cycle begins with menstruation (day 1), the shedding of the endometrial lining
Menstruation Details
- Endometrium sheds and bleeds due to cyclic ovulation
- The non-clotting menstrual blood comes primarily from arteries (approximately 75%).
- Typical cycle interval is 21-40 days (average 28 days).
- Duration of bleeding is typically 1-7 days
- The first day of bleeding is considered day 1.
Changes in Pituitary Hormones (Days 1-14)
- During the first half of the cycle, the pituitary releases FSH to stimulate egg production.
- FSH also triggers the release of estrogen from the ovaries.
Changes in Pituitary Hormones (Days 14-28)
- On day 14, the pituitary releases LH, which triggers ovulation.
- LH also directs the production of progesterone.
- Progesterone maintains the growth of the endometrium
- If the egg is not fertilized, progesterone levels drop, causing estrogen levels to drop, leading to menstruation.
Ovarian Cycle
- The ovarian cycle is controlled by the hypothalamus-pituitary axis.
- The cycle is divided into follicular, ovulatory, and luteal phases.
- The follicular phase involves follicle growth, estrogen production, and preparation for ovulation.
- The ovulatory phase includes the release of the egg.
- The luteal phase involves corpus luteum formation, progesterone production, and maintenance of the uterine lining for possible pregnancy.
Changes in the Ovaries
- Stage 1: Ovum begins development
- Stage 2: The egg continues to ripen; follicle grows
- Stage 3: Ovulation (fully mature egg bursts out of follicle)
- Stage 4: The egg enters the fallopian tube; the follicle forms the corpus luteum
Follicular Phase
- Several follicles start to grow after puberty.
- Most follicles become atretic (degenerate), but one matures.
- Granulosa cells create estrogen and some progesterone, which are the principle sources of estrogen within the follicle fluid.
- Theca interna cells form additional estrogens.
- Estrogen and other hormones exert negative feedback on FSH and LH
Ovulatory Phase
- The rising estrogen towards the mid-cycle triggers positive feedback on FSH and LH, resulting in follicle rupture and egg release into the abdominal cavity
- The egg enters the fallopian tube to travel to the uterus.
Luteal Phase
- Following ovulation, the ruptured follicle transforms into the corpus luteum.
- Luteal cells produce primarily estrogen and progesterone.
- This phase results in negative feedback on FSH and LH.
- If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in estrogen and progesterone levels and subsequent menstruation.
- If fertilization occurs, HCG is produced to maintain corpus luteum and keep producing estrogen and progesterone.
Uterine Cycle
- The endometrial lining thickness increases during the proliferative phase in response to rising estrogen levels.
- The lining becomes thick and soft during the secretory phase as progesterone causes secretions of nutrients into the lining for a potential embryo.
- If no pregnancy occurs, the superficial layer of the uterus is shed during the menstrual phase.
Menstrual Phase
- The shedding of the stratum functionale (superficial layer of endometrium) occurs after 3-5 days because of the lack of estrogen and progesterone.
- The blood loss is generally arterial (30 mL).
- The lost blood is non-clotting due to fibrinolytic substances (fibrinolysin)
- Prostaglandins and cellular debris are also present.
Indicators of ovulation
- Rise in body temperature due to progesterone’s thermogenic effect
- LH surge (peak)
- Development of the secretory phase in endometrium
- Lower abdominal pain
Terms used to describe menstrual abnormalities
- Primary amenorrhea (absence of menstrual bleeding)
- Secondary amenorrhea (absence of menstrual bleeding after it began normally)
- Dysmenorrhea (painful menstruation)
- Hypomenorrhea (scant menstrual bleeding)
- Menorrhagia (excessive menstrual bleeding)
- Metrorrhagia (bleeding from the uterus between periods)
Additional notes on Anovulatory Cycle
- Some cycles may occur without ovulation.
- The bleeding in anovulatory cycles is caused by rising and falling estrogen levels.
- Anovulatory cycles can occur before menopause and following menarche
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Description
Explore the intricacies of menstruation and the female reproductive system in this quiz. The content covers the menstrual cycle, hormonal regulation, and physiological stages from birth to menopause. Test your understanding of these vital concepts in women's health.
