Human Anatomy: Uterine Layers and Menstrual Cycle

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Questions and Answers

What are the layers of the endometrium?

Endometrium, myometrium, perimetrium

Fibrinogenic layer, epithelial layer, muscular layer

Basal layer, transitional layer, glandular layer

Stratum compactum, stratum spongiosum, stratum basale (correct)

During which phase of the menstrual cycle does ovulation occur?

Menstrual phase

Luteal phase (correct)

Proliferative phase

Follicular phase

What hormone predominantly influences the changes during the follicular phase?

Testosterone

Estrogens (correct)

Luteinizing hormone

Progesterone

What is the typical duration of the follicular phase?

14-21 days Signup and view all the answers

What initiates the onset of menstrual bleeding if pregnancy does not occur?

Degeneration of the corpus luteum Signup and view all the answers

Which phase is characterized by the highest level of fertility?

Follicular phase Signup and view all the answers

What happens to the spiral arteries during the menstrual phase?

They constrict and cut off blood supply Signup and view all the answers

What is the immediate effect of the rise in luteinizing hormone (LH) during the menstrual cycle?

Initiation of ovulation Signup and view all the answers

What happens to the cervical mucus just before ovulation?

It becomes profuse, thin, clear and viscid Signup and view all the answers

Which of the following layers constitutes the outer covering of the uterus?

Perimetrium Signup and view all the answers

What is the role of inhibin in the menstrual cycle if fertilization does not occur?

It inhibits gonadotropin secretion Signup and view all the answers

How does body temperature change around the time of ovulation?

There is a sudden fall followed by a rise Signup and view all the answers

What defines an anovulatory menstrual cycle?

No ovulation and absence of a luteal phase Signup and view all the answers

Which hormone is primarily responsible for the increase in body temperature after ovulation?

Progesterone Signup and view all the answers

What effect does the fall in estrogen and progesterone levels have during menstruation?

Constriction of spiral arteries Signup and view all the answers

Which symptom may indicate ovulation occurs in some women?

Slight uterine bleeding mid-cycle Signup and view all the answers

What components make up the composition of menstrual flow?

Degenerated endometrial layers and secretions of uterine glands Signup and view all the answers

Which phase of the menstrual cycle lasts for about 14 days and is under the influence of progesterone?

Luteal phase Signup and view all the answers

Which statement correctly describes the changes in the endometrium during the proliferative phase?

It increases in thickness and becomes more vascular. Signup and view all the answers

What triggers the surge in LH levels 24-36 hours before ovulation?

A peak in estrogen levels Signup and view all the answers

How does the endometrium appear at the beginning of the menstrual cycle?

Thin and sparsely vascular Signup and view all the answers

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

It degenerates and hormone levels fall Signup and view all the answers

During the luteal phase, which of the following changes occurs in the glands of the endometrium?

They become tortuous and distended with fluid rich in nutrients Signup and view all the answers

Which layer of the endometrium is not shed during menstruation?

Basal layer Signup and view all the answers

Study Notes

Uterine Structure

The uterus has three main layers:
- Endometrium: Inner mucosal lining.
- Myometrium: Thick layer of smooth muscle.
- Perimetrium: Serosa or peritoneal covering of the uterus.

Endometrium Composition

The endometrium consists of three layers:
- Stratum compactum: Compact layer.
- Stratum spongiosum: Spongy layer.
- Stratum basale: Basal layer.

Menstrual Cycle Phases

The menstrual cycle includes 3 or 4 overlapping phases:
- Menstrual phase
- Proliferative phase
- Secretory phase
- Ovulation is also considered a separate phase.

Follicular Phase

Lasts from the first day of menstruation until ovulation (14 to 21 days).
Characterized by the influence of estrogen from developing ovarian follicles.
Involves growth of ovarian follicles, leading to one mature ovum.
Most fertile period occurs at the end of this phase.

Luteal Phase

Begins after ovulation and lasts about 14 days, ending with menstrual flow.
Governed by progesterone secreted by the corpus luteum.
Progresses through an ischaemic phase if pregnancy does not occur.

Menstrual Phase Dynamics

Lasts for 3-7 days; marked by shedding of compact and spongy endometrial layers if pregnancy does not occur.
Degeneration of the corpus luteum leads to a drop in estrogen and progesterone, causing menstrual bleeding.
Menstrual flow consists of:
- Blood
- Degenerated endometrial tissue
- Secretions from uterine glands (rich in lipids and glycogen).
Average blood loss during menstruation is about 35-45 mL (range 5-80 mL).

Proliferative Phase

Lasts for about 6-14 days post-menstruation.
Coincides with ovarian follicle growth and increased estrogen production.
Endometrial thickness increases threefold, marking distinct endometrial layers.

Secretory Phase (Luteal Phase)

Constant duration of 14 days post-ovulation.
Endometrium reaches maximum thickness under progesterone influence.
Glands become tortuous, distended with fluid rich in glycogen and lipids.

Hormonal Fluctuations

Estrogen peaks two days before ovulation, triggering a surge in LH.
LH surge initiates ovulation; FSH peaks shortly before.
If fertilization does not occur, granulosa cells secrete inhibin, suppressing gonadotropin release and causing regression of the corpus luteum and shedding of the endometrium.

Signs of Ovulation

Body Temperature: Biphasic pattern with a drop followed by an increase post-ovulation.
Cervical Mucus: Becomes thin, clear, and profuse pre-ovulation; thickens post-ovulation.
Mittelschmerz Pains: Mild lower abdomen pain due to irritation from blood or fluid during ovulation.
Increased Ferning: Vaginal smears show epithelial cornification at ovulation.

Menstrual Cycle Regulation

Regulated by the hypothalamus, which secretes GnRH affecting the anterior pituitary to release FSH and LH for ovary cyclic changes.

Anovulatory Menstrual Cycle

Occurs without ovulation, leading to absence of the luteal phase.
Minimal changes happen in the endometrium.

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Description

This quiz covers the layers of the uterus, including the endometrium, myometrium, and perimetrium, as well as the structures within the endometrium. It also explores the phases of the menstrual cycle. Test your knowledge of female reproductive anatomy and physiology.