Menstrual Cycle Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which phases are included in the ovarian cycle?

Ovulatory and Follicular

Secretory and Menstrual

Follicular and Luteal (correct)

Menstrual and Proliferative

What occurs during the menstrual phase of the cycle?

Luteinization of ovarian follicles

Ovulation of the oocyte

Shedding of the endometrium and thinning (correct)

Endometrial thickening due to progesterone

During which phase does the endometrium thicken in preparation for possible implantation?

Menstrual phase

Luteal phase

Follicular phase

Proliferative phase (correct)

What hormone influences the regeneration of the endometrium after menstruation?

Estrogen Signup and view all the answers

Which of the following accurately describes the phases of the menstrual cycle?

The ovarian cycle corresponds with the endometrial cycle. Signup and view all the answers

What occurs in the ovaries during the luteal phase?

Formation of the corpus luteum Signup and view all the answers

Which cycle phase corresponds to the follicular phase of the ovarian cycle?

Proliferative phase Signup and view all the answers

Which statement is true about the endometrial and ovarian cycles?

The proliferative phase occurs during the follicular phase. Signup and view all the answers

What role does estrogen play in the menstrual cycle?

It stimulates the thickening and regeneration of the endometrial lining. Signup and view all the answers

What initiates the menstrual cycle and is considered the first day of the cycle?

The first day of menstruation (bleeding). Signup and view all the answers

Which hormone is primarily responsible for signaling the anterior pituitary to secrete gonadotropins?

Gonadotropin-releasing hormone (GnRH) Signup and view all the answers

What event occurs during the proliferative phase of the menstrual cycle?

Follicles are recruited, and one mature follicle prepares to ovulate. Signup and view all the answers

What is the role of granulosa cells in early pregnancy?

Secreting estrogen to aid in the maintenance of the oocyte. Signup and view all the answers

How long does a typical menstrual cycle last?

28 to 35 days Signup and view all the answers

What is the function of angiogenesis during the menstrual cycle?

To ensure successful implantation of the embryo by vascularizing the endometrium. Signup and view all the answers

What happens to the corpus luteum if fertilization does not occur?

It undergoes apoptosis 9-11 days after ovulation. Signup and view all the answers

What is the role of follicle stimulating hormone (FSH) in the menstrual cycle?

It stimulates the ovaries for certain mechanisms including follicle development. Signup and view all the answers

Why is the corpus luteum important during early pregnancy?

It produces hormones that support the pregnancy until the placenta forms. Signup and view all the answers

Where does fertilization typically occur?

In the ampulla of the fallopian tube. Signup and view all the answers

Which component of the reproductive system is involved in regulating the menstrual cycle?

The hypothalamic-pituitary-ovarian axis (HPO axis) Signup and view all the answers

What is the consequence of decreased levels of progesterone and estrogen?

Termination of early pregnancy support. Signup and view all the answers

What role does the fimbriae of the fallopian tube play?

They assist in collecting the egg released from the ovary. Signup and view all the answers

What is the primary role of CSF-1 in the implantation process?

To promote differentiation in the endometrial epithelium and stroma Signup and view all the answers

What is the role of theca cells during early pregnancy?

They secrete estrogen alongside granulosa cells. Signup and view all the answers

What occurs during the initial stage of implantation, known as apposition?

The blastocyst makes initial contact with the uterine wall Signup and view all the answers

Which of the following describes the hormone secretion prior to pregnancy confirmation?

Progesterone secretion is crucial for maintaining pregnancy support. Signup and view all the answers

What is the fate of the embryo if implantation does not occur within the uterus?

It may result in an ectopic pregnancy Signup and view all the answers

Which structure is primarily responsible for embedding into the endometrium during invasion?

The syncytiotrophoblast Signup and view all the answers

After how many days following fertilization does the blastocyst typically implant into the uterine wall?

6 to 7 days Signup and view all the answers

During what stage does the blastocyst experience increased physical contact with the uterine epithelium?

Adherence Signup and view all the answers

Which hormone is primarily involved in making the uterine environment receptive for implantation?

Progesterone Signup and view all the answers

What is the role of interleukins released by the blastocyst during the implantation process?

To facilitate communication with maternal tissues Signup and view all the answers

What initiates the secretion of FSH in the ovarian cycle?

GnRH from the hypothalamus Signup and view all the answers

Which phase of the ovarian cycle involves the maturation of the Graafian follicle?

Follicular Phase Signup and view all the answers

What is the role of progesterone in early pregnancy?

Stimulates the thickening of the endometrium Signup and view all the answers

What occurs due to hormonal withdrawal in the endometrial cycle?

Menstruation of the endometrial lining Signup and view all the answers

What hormone does the corpus luteum continue to secrete after fertilization occurs?

hCG Signup and view all the answers

Which of the following is NOT a function of estrogen in the endometrial cycle?

Enhances menstrual shedding of the lining Signup and view all the answers

What triggers the release of LH from the anterior pituitary?

Rising levels of GnRH Signup and view all the answers

What is the primary purpose of the thickening of the endometrial lining?

To create a suitable environment for implantation Signup and view all the answers

Study Notes

HPO Axis and Menstrual Cycle

The Hypothalamic-Pituitary-Ovarian (HPO) axis regulates the menstrual cycle.
The hypothalamus secretes gonadotropin-releasing hormone (GnRH) to stimulate the anterior pituitary, leading to the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
The menstrual cycle includes both an endometrial cycle (proliferative and secretory phases) and an ovarian cycle (follicular and luteal phases).
A typical menstrual cycle lasts 28 to 35 days, starting on the first day of menstruation and concluding just before the next period.

Endometrial Cycle

The endometrial cycle has three phases: menstruation, proliferative, and secretory.
During menstruation, the endometrium sheds due to a drop in hormone levels, leading to menstrual bleeding.
The proliferative phase correlates with the follicular phase of the ovarian cycle, where estrogen promotes thickening of the endometrial lining to prepare for possible implantation.

Ovarian Cycle

The ovarian cycle consists of the follicular phase and the luteal phase.
In the follicular phase, multiple follicles mature, but one becomes dominant (Graafian follicle) and prepares for ovulation.
Estrogen from the dominant follicle triggers the thickening of the endometrium, ensuring it is well-vascularized for potential implantation.
The luteal phase follows and is characterized by the formation of the corpus luteum, which secretes progesterone to maintain the endometrial lining.

Hormonal Changes and Fertilization

If fertilization does not occur, the corpus luteum degenerates 9-11 days post-ovulation, causing decreased progesterone and estrogen levels, leading to menstruation.
If fertilization occurs, the corpus luteum produces hCG to sustain the pregnancy until the placenta develops.
Fertilization usually occurs in the ampulla of the fallopian tube, where sperm meets the egg.

Implantation Process

After fertilization, the embryo (blastocyst) travels to the uterus for implantation, typically occurring 6-7 days post-fertilization.
Implantation involves three stages:
- Apposition: Initial contact with the uterine wall.
- Adherence: Increased physical interaction with uterine epithelium.
- Invasion: Trophoblasts penetrate the endometrium, reaching the myometrium.
Syncytiotrophoblasts, derived from the outer layer of the blastocyst, play a vital role in establishing the placenta.

Key Terminology

Primary Oocyte: The initial stage of the egg.
Colony-Stimulating Factor 1 (CSF-1): Hormone crucial for implantation by promoting endometrial receptiveness.
Decidua: The name for the endometrium during pregnancy; an essential site for implantation.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the intricacies of the menstrual cycle, including the HPO axis and its relation to the endometrial and ovarian cycles. This quiz covers distinct phases such as the menstrual and proliferative phases, along with their physiological significance.