30 Questions
How many primary oocytes are approximately formed and stored in each ovary at birth?
One million
What is the approximate number of primary oocytes left in both ovaries by puberty?
300,000
How many oocytes are released during a woman’s lifetime?
400–500
What is the primary function of granulosa cells?
Nourish the primary oocyte
When does the menstrual cycle generally begin?
Puberty
What controls the menstrual cycle?
Hormones
What are the two linked cycles that make up a complete menstrual cycle?
Ovarian cycle and uterine cycle
What happens to the menstrual cycle during pregnancy?
It stops
How long does the menstrual cycle last on average?
28 days
What happens to the primary oocytes at birth?
Further development halts until after puberty
What stimulates the development of the oocyte and the secretion of estrogen?
FSH
What hormone triggers ovulation?
LH
What inhibits GnRH, FSH, and LH secretion during most of the cycle?
Increases in estrogen and progesterone
What hormone is secreted by the corpus luteum?
Progesterone
What event accounts for why the female hormonal pattern is cyclical?
A single positive feedback event just before the midpoint of the cycle
What prevents a second ovulation from taking place until the cycle is complete?
High but steady levels of estrogen and progesterone from the corpus luteum
What triggers ovulation at the precise moment that the follicle is ready?
High estrogen triggering the LH surge
What causes the LH surge to be short-lived during the second half of the menstrual cycle?
High but steady levels of estrogen and progesterone from the corpus luteum
What delays the start of another cycle until the body determines whether or not pregnancy has taken place?
High but steady levels of estrogen and progesterone from the corpus luteum
What hormone is responsible for preventing the next follicle from developing without LH and FSH?
Progesterone
What triggers ovulation in the ovarian cycle?
Surge in LH
What leads to the thickening of the endometrial lining during the uterine cycle?
Production of estrogen and progesterone by the corpus luteum
What happens to the corpus luteum if fertilization does not occur?
It degenerates
Which hormone is secreted by the corpus luteum in preparation for a potential fertilized egg?
Progesterone
What is the role of FSH in the ovarian cycle?
Stimulates granulosa cell division and glycoprotein secretion
What is the function of the chorion in the uterine cycle?
Secretes hCG
What causes the disintegration of the endometrial lining during the menstrual phase?
Declining estrogen and progesterone levels
What leads to the release of the secondary oocyte in the ovarian cycle?
Rupture of the follicle due to surge in LH
What hormone signals the corpus luteum to produce progesterone and estrogen if pregnancy occurs?
hCG
What are the symptoms associated with the menstrual cycle?
PMS, dysmenorrhea, hormonal and physical changes
Study Notes
The Ovarian and Uterine Cycles
- The ovarian cycle begins with the release of GnRH from the hypothalamus, stimulating the secretion of FSH and LH by the anterior pituitary, leading to follicle growth and estrogen secretion.
- FSH stimulates granulosa cell division and the secretion of glycoproteins around the oocyte, while the antrum develops within the follicle and estrogen levels increase.
- The primary oocyte completes stage I of meiosis, forming a secondary oocyte and a polar body within the mature Graafian follicle.
- Ovulation is triggered by a surge in LH, causing the follicle to rupture and release the secondary oocyte, polar body, and granulosa cells into the extracellular fluid.
- The remaining follicle becomes the corpus luteum, which secretes progesterone in preparation for a potential fertilized egg, and degenerates if fertilization does not occur.
- If pregnancy occurs, the chorion secretes hCG, signaling the corpus luteum to produce progesterone and estrogen, which is later taken over by the placenta.
- The uterine cycle is linked to the ovarian cycle and involves menstrual, proliferative, and secretory phases, preparing the endometrium for potential pregnancy.
- During the menstrual phase, declining estrogen and progesterone levels lead to the disintegration of the endometrial lining and the shedding of tissue and blood.
- The proliferative phase is characterized by the thickening of the endometrial lining and the production of watery cervical mucus to facilitate sperm passage, leading to ovulation.
- The secretory phase involves the production of estrogen and progesterone by the corpus luteum, causing further endometrial thickening and the preparation of the uterus for a developing embryo.
- If fertilization does not occur, the degeneration of the corpus luteum leads to declining hormone levels and the start of another menstrual cycle.
- The menstrual cycle may cause discomfort, including symptoms such as PMS, dysmenorrhea, and hormonal and physical changes, which can be managed with exercise and medications.
Test your knowledge of the ovarian and uterine cycles with this quiz. Explore the hormonal and physiological processes involved in follicle development, ovulation, corpus luteum function, and the stages of the uterine cycle. Gain insights into the interplay of hormones, the preparation of the endometrium for potential pregnancy, and the management of menstrual cycle discomfort.
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