Exam 4 | Reproductive pt. 2

Question 1

How can the female reproductive system be divided into?

Answer 1

Into internal and external structures

Question 2

What are the external structures in the female reproductive system?

Answer 2

clitoris, labia majora & minora, vaginal opening, and hymen

Question 3

What are the internal structures in the female reproductive system?

Answer 3

Ovaries, fallopian tubes, uterus, cervix, and vagina

Question 4

How many layers make up the uterine lining?

Answer 4

2 layers; the endometrium and myometrium

Question 5

Describe the endometrium.

Answer 5

It is the innermost layer of the uterus which thickens in preparation of implantation of an egg which happens during menstrual cycle and pregnancy

Question 6

Describe the myometrium.

Answer 6

The myometrium is the muscle layer of the uterus; smooth muscle and involuntary control; contributes to uterine contractions necessary for labor and contributes to menstrual cycle as well

Question 7

What’s another name for eggs?

Answer 7

Oocytes

Question 8

Do biological females actively make eggs?

Answer 8

Biological females are born with all the eggs they’re going to have, they do not produce any more new oocytes after birth

Question 9

Where are these eggs found?

Answer 9

While the oocytes (eggs) have already been produced in utero (i.e. prior to birth), the structures that contain these eggs, known as follicles, develop on a continuous basis once a female reaches puberty.

Question 10

What does the release of FSH do?

Answer 10

Follicles develop in response to the release of FSH, and by the time ovulation occurs in the menstrual cycle (typically around Day 14), the level of LH peaks, triggering the expulsion of the egg from the follicle.

Question 11

What’s the corpus luteum? What hormone does it produce?

Answer 11

It’s the remnants of the follicle after it ruptures to release an egg; secretes progesterone which acts directly on the myometrial lining to temporarily inhibit muscle contractions in preparation for the implantation of the egg released from its follicle.

Question 12

How long does the female Hypothalamic-Pituitary-Gonad axis last for?

Answer 12

A course of a 28 day menstrual cycle roughly

Question 13

What’s the first half of the menstrual cycle known as?

Answer 13

The follicular phase

Question 14

What happens during the follicular phase?

Answer 14

During this phase, the Hypothalamic-Pituitary-Gonad (HPG) Axis is primarily triggering the release of Follicle Stimulating Hormone (FSH), which rises gradually over the course of 10-14 days to stimulate the production and release of estrogen; days 1-13

Question 15

Midway through the menstrual cycle, what happens?

Answer 15

Mid-way through the menstrual cycle, ovulation occurs, at which point the level of Luteinizing Hormone (LH) secreted from the anterior pituitary increases dramatically, triggering the release of an egg from its follicle inside one of the ovaries; approximately day 14

Question 16

What’s the second half of the menstrual cycle known as?

Answer 16

The luteal phase

Question 17

What happens in the luteal phase?

Answer 17

During this phase, the Hypothalamic-Pituitary-Gonad (HPG) Axis is largely inhibited, and the production/ secretion of both FSH and LH gradually decreases. At the same time, the corpus luteum in the ovary from which the egg was secreted produces progesterone to relax the uterus in preparation for implantation of the egg; day 15-28

Question 18

What’s oogenesis?

Answer 18

The process of producing new egg cells which takes place in the ovaries during fetal development. This process is nearly identical to spermatogenesis.

Question 19

Describe the process for oogenesis.

Answer 19

1) The first cell to be produced (or rather, copied) is the oogonium, which is an undifferentiated diploid (2n) cell. These oogonia undergo a single round of mitosis to produce the primary oocyte.

2) After the primary oocyte is produced, this cell undergoes Meiosis I to produce two haploid (1n) cells, one of which will become a functional cell (the secondary oocyte) while the other is not considered to be a “functional” cell (known as a primary polar body).

3) The secondary oocyte and primary polar body will each further divide in Meiosis II to produce four haploid (1n) cells, three of which are secondary polar bodies and one of which is a functional cell known as the ovum (mature egg cell).

Question 20

What’s menses?

Answer 20

The last 3-5 days of the menstrual cycle which results in bleeding due to loss of endometrial lining.

Question 21

What causes menses?

Answer 21

When fertilization of the egg does not occur, no implantation occurs in the lining which causes it to shed since it got thick in preparation.

Question 22

What is fertilization and where does it occur?

Answer 22

When a sperm and egg meet, fertilization occurs, and this process typically takes place in the upper third (ampulla) of the fallopian tube.

Question 23

How does an egg travel through the fallopian tube?

Answer 23

During ovulation, a single ovum (egg) is expelled from a follicle in one of the two ovaries, and the egg is then propelled to the uterus via cilia lining the internal wall of the fallopian tube. The egg is initially picked up by “fingers”, known as fimbriae, at the “entrance” of the fallopian tube.

Question 24

How many sperms fertilize an egg?

Answer 24

Only 1

Question 25

Upon meeting the egg, what physical barriers must the sperm pass thorugh in order to penetrate the egg?

Answer 25

The follicle cells that surround the egg; The jelly coat of the egg itself; Receptor proteins expressed on the Vitelline membrane; The actual plasma membrane of the egg

Question 26

Once a single sperm cell penetrates the egg, what happens next?

Answer 26

After binding to species-specific receptors, an intracellular cascade within the egg takes place to prevent multiploidy

Question 27

What happens inside the egg that prevents multiploidy?

Answer 27

Rapid depolarization of the egg (becomes more positively-charged)

The chemical IP3 is formed, triggering release of Calcium (Ca2+) from the endoplasmic reticulum

Vesicles are released from the egg which harden the jelly coat to prevent additional sperm from entering the egg at this point (would lead to multiploidy, which typically results in non-viable zygote).

Vitelline layer also shifts position so that no additional sperm can enter the egg.

Question 28

After fertilization occurs, the egg is now referred to as…

Answer 28

A zygote

Question 29

During the first four days after fertilization, the zygote undergoes…

Answer 29

rapid cell divisions (mitosis), known as cleavages

Question 30

What happens on day 1 of zygote cell division?

Answer 30

On Day 1, the zygote has divided once, forming two cells; known as the two-cell stage

Question 31

What happens on day 2 of zygote cell division?

Answer 31

On Day 2, the zygote has entered the four cell stage

Question 32

What happens on day 4 of zygote cell division?

Answer 32

By Day 4, the zygote has entered the morula stage

Question 33

What happens on day 5 of zygote cell division?

Answer 33

By Day 5, the zygote has entered the blastula stage

Question 34

What happens to the zygote during the four cleavages?

Answer 34

The overall size of the zygote does not change throughout these divisions, and it continues to migrate towards the uterine lining for implantation.

Question 35

During weeks 5-8 of gestation, the zygote is now referred to as…

Answer 35

A fetus

Question 36

What happens during weeks 5-8 of gestation?

Answer 36

The presence or absence of sex hormones will determine the direction in which sex differentiation (or development of the primary sex organs, including the gonads) will proceed.

Question 37

What will cause the development of female organs?

Answer 37

Generally-speaking, the female reproductive organs, collectively referred to as the Müllerian Duct, are considered to be the “default” state of sex differentiation (i.e. these structures will form when no other chemical cues/ hormones are present).

Question 38

What will cause the development of male organs?

Answer 38

If androgens (male sex hormones) such as testosterone are present, the non-specified sex organs will differentiate into the male reproductive organs, collectively known as the Wolffian Duct.

Question 39

What happens if there’s in imbalance of sex hormones in the uterus?

Answer 39

Abnormal levels of sex hormones present in utero can lead to incomplete or improper formation of the primary sex organs, leading to rare conditions such as intersex development.

Question 40

What happens during childbirth/ labor?

Answer 40

The release of the posterior pituitary hormone oxytocin in response to dilation of the cervix during labor follows a positive feedback loop.

Question 41

How does the body know when to produce oxytocin?

Answer 41

Ascending (afferent) neural projections from the cervix that detect the dilation (widening) of this structure stimulate the secretion of oxytocin from the posterior pituitary gland, which then travels via the bloodstream to reach the myometrium to stimulate contractions that will push the baby’s head towards the cervix. This causes the cervix to further dilate, and thus, a spiral occurs that continuously results in oxytocin secretion throughout the labor process.

Question 42

After 3-4 weeks of labor, what hormone is prevalent in the body?

Answer 42

The anterior pituitary hormone prolactin will be secreted in high concentrations in order to promote the production of breast milk in the mammary glands, as well as inhibit the release of Gonadotropin-releasing Hormone (GnRH) from the hypothalamus to temporarily “shut off” the HPG axis, thus preventing a woman from becoming pregnant again for a short period of time.

Question 43

Along with prolactin, what’s the other hormone that works alongside it? Why is it important?

Answer 43

Oxytocin plays a role in milk “let down” (release of breast milk) in response to suckling from the nursing infant. This cycle of oxytocin secretion for milk “let down” also follows a positive feedback loop, in that increased suckling stimulation results in increased oxytocin release, which in turn causes more milk to be released.

Question 44

What’s a prenatal diagnostic procedure commonly recommended to women with high-risk pregnancies, as well as women who are pregnant after the age of 35?

Answer 44

Amniocentesis is a procedure which involves collecting a small sample of the amniotic fluid, in order to analyze the genetic material that can be extracted from this fluid.

Question 45

What do pathologists look for during the amniocentesis procedure?

Answer 45

Pathologists will check the physical structure of the chromosomes of the fetus to ensure that there are no significant genetic or chromosomal abnormalities that may result in a genetic/ chromosomal disease (such as Trisomy 21, more commonly known as Downs Syndrome, among others).

Question 46

Why are women over the age of 35 recommended amniocentesis?

Answer 46

The reason why this procedure is strongly recommended for pregnant women over the age of 35 is that they typically have a greater risk of having a fetus with a genetic abnormality due to the higher rates of abnormal cell division that occur in older women.