Reproductive System- Processes

Question 1

How long can an egg survive after it is released in ovulation?

Answer 1

24 hours

Question 2

What is the source of a positive home pregnancy test?

Answer 2

human chorionic gonadotropin (HCG)
This is secreted by the blastocyst to stimulate the corpus luteum to secrete progesterone, which increases the blood supply to the endometrium. The endometrium secretes glycogen to sustain the blastocyst before implantation.

Question 3

What are the three layers developed by the blastocyst upon implantation in the endometrium?

Answer 3

The ectoderm is the outer layer
The mesoderm is the middle layer
The endoderm is the inner layer

Question 4

What body parts develop from each layer?

Answer 4

Ectoderm- skin and nervous tissue
Endoderm- Glands (thyroid, parathyroid, thymus glands), several solid organs (liver and pancreas) and the lining of the hollow organs of digestive and respiratory systems
Mesoderm- all other tissues, including the cardiovascular system, red blood cells and muscle

Question 5

What is the function of the placenta?

Answer 5

To provide the embryo and fetus in the uterus with nutrition. It is a temporary organ that carries out nutritive,excretory, endocrine and respiratory functions for the embyro. The placenta is attached to the embryo by the umbilical cord.

Question 6

How many trimesters are there a pregnancy?

Answer 6

1st, 2nd and 3rd Trimesters

Question 7

What is the length of each trimester?

Answer 7

1st Trimester (0-12 weeks,) 
2nd Trimester (13-28 weeks)
3rd Trimester (29-40 weeks)

Question 8

Highlights from the 1st Trimester

Answer 8

The head is formed but is disproportionately large for the majority of the first trimester. The brain, spinal cord and limbs begin to form. The eyes, ears, and nose begin to form but are not necessarily in their correct location yet. The heart forms and begins pumping blood. By the end of week eight the embryo is now considered a fetus and begins to move, but movement is not yet felt by the mother. Finally, the genitals begin to form.

Question 9

Highlights from the 2nd Trimester

Answer 9

The eyes, ears, and nose move to the correct position on the face and head and the body is growing to its proper proportion. The fetus begins to suck and blink and fetus’ fingerprints develop. The mother begins to feel the fetus move in the womb. Lanugo or hair develops on the fetus’ body to keep it warm. The fetus develops sleep/wake cycles and the heart beats at a regular pattern.

Question 10

Highlights from the 3rd Trimester

Answer 10

The third trimester is characterized by continued development of the systems in place. For boys, the testes descend into the scrotum. The baby increases in weight and begins to develop fat under the skin. The lungs continue to develop and the baby begins to regulate its own temperature.

Question 11

How does the mother’s body adapt to pregnancy?

Answer 11

As the baby is growing during pregnancy and changing, so is the mother’s body. The uterus enlarges significantly and fills up the abdominal cavity by the end of pregnancy. The female’s breasts grow and prepare to produce milk for the new baby. The cardiovascular system increases blood volume and the respiratory system increases the respiratory rate. The kidneys increase urine output because of the fetal waste. As the female’s abdomen expands to accommodate the uterus, her center of gravity shifts and causes an increase in lumbar curvature. The pubic symphysis expands and the pelvis ligaments relax and become more flexible to allow room for the baby at delivery. Other common changes during pregnancy are heartburn, morning sickness, and constipation.

Question 12

1st stage of Delivery

Answer 12

The first stage, dilation of the cervix, is the time it takes for the woman’s cervix to dilate to ten centimeters. During this stage the uterus contracts, which pushes the baby’s head against the cervix causing it to dilate. This stage of labor is the longest, lasting, on average 6-10 hours.

Question 13

2nd stage of Delivery

Answer 13

The second stage, delivery of the baby, is the time it takes for the baby to be pushed out of the birth canal after full dilation has been accomplished. During this stage a woman uses her abdominal muscles to push the baby, with the help of the uterus contracting, through the cervix and out the vagina. This stage is much shorter, lasting, on average, 50 minutes in a first delivery and 20 minutes in later ones. After the child is born the umbilical cord is tied and cut. Babies are typically born head first but if the baby is in a different position such as a buttock-first (breech), it can cause complications for the mother and child. In breech and other especially long and difficult deliveries, a cesarean section is performed, in which the baby is delivered through a surgical incision made through the abdominal and uterine walls.

Question 14

3rd Delivery

Answer 14

Delivery of the Placenta- when the placenta is pushed out of the birth canal. This occurs within 15 minutes of the birth of the child and is the shortest part of labor. The entire placenta needs to be removed after birth or uterine bleeding will continue. The placenta is referred to as the afterbirth.

Question 15

What is oogenesis?

Answer 15

Oogenesis is the production of eggs in the ovaries which occurs during development of the fetus in the womb and is complete by the time of birth. Therefore, at birth a female has all of the immature eggs that she can later ovulate during her reproductive lifetime which extends from puberty to about her 50th year of life. The end of the female reproductive lifetime is known as menopause.

Question 16

What are the stem cells that become eggs known as? What are the daughter cells called after undergoing mitotic division?

Answer 16

Stem cells, known as oogonia, undergo mitotic division into two daughter cells known as primary oocytes. These primary oocytes are covered by follicles, known as primary follicles. This process is completed by birth.

Question 17

Primary oocytes are covered by what structures? What are these known by?

Answer 17

Primary oocytes are covered by follicles, known as primary follicles.

Question 18

What effect does Follicle stimulating hormone have?

Answer 18

In puberty, FSH begins to be secreted by the anterior pituitary gland which causes a few follicles to mature each month.

Question 19

What happens once FSH is secreted in puberty?

Answer 19

This hormone causes a few follicles to mature each month. The primary oocyte in the follicle undergoes its first meiotic division into two daughter cells: the secondary oocyte and the first polar body.

Question 20

What happens if the secondary oocyte is united with a sperm after ovulation ?

Answer 20

If the secondary oocyte is united with a sperm after ovulation the second meiotic division occurs which produces a second polar body and an ovum with 23 chromosomes. The ovum and the sperm combine their chromosomes to form a fertilized egg with 46 chromosomes.

Question 21

What happens to the first polar body produced in the 1st meiotic division?

Answer 21

It may or may not undergo a second meiotic division. Therefore females produce two to three polar bodies and one viable gamete or ovum with 23 chromosomes.

Question 22

What happens if the secondary oocyte does not combine with a sperm ?

Answer 22

It dies and menstruation occurs.

Question 23

What action does the Luteinizing hormone perform? What gland is it secreted by ?

Answer 23

Around the time of ovulation the anterior pituitary secretes a second hormone called luteinizing hormone (LH). This causes the follicle to become the corpus luteum which is necessary for maintaining pregnancy.

Question 24

What is menstruation ?

Answer 24

The shedding of the inner endometrium layer of the uterus if a zygote is not implanted.

Question 25

How are the ovarian cycle and the menstrual cycle integrated ?

Answer 25

Every month the ovaries release hormones (estrogen and progesterone) that cause changes to the endometrium, the innermost layer of the uterus, which provides the site for implantation if fertilization occurs and if not it is shed (every 28 days).

Question 26

What are the 3 phases of the menstrual cycle?

Answer 26

the menstrual phase, the proliferative phase, and the secretory phase.

Question 27

What happens in the menstrual phase of the menstrual cycle?

Answer 27

The menstrual phase begins on day 1 when all but the innermost basal layer of the endometrium is shed and continues through day five. The detached tissue and blood flow from the uterus into the vagina and exit the body via the vaginal orifice as the menstrual flow.

Question 28

What happens in the proliferative phase of the menstrual cycle?

Answer 28

The proliferative phase occurs during days 6-14 as the endometrium rebuilds in response to increasing estrogen levels. Ovulation of an egg typically occurs in the ovaries on day 14. This is a result of the anterior pituitary release of luteinizing hormone as a response to high levels of estrogen.

Question 29

What happens in the secretory phase of the menstrual cycle?

Answer 29

The final phase of the cycle is the secretory phase which occurs during days 15-28. During this phase the corpus luteum begins to secrete progesterone. Progesterone causes an increased blood supply in the uterus and secretion of nutrients glycoproteins. This prepares the uterus for implantation if an egg has been fertilized

Question 30

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

Answer 30

the corpus luteum dies and the endometrium’s blood supply decreases as a result of decreased progesterone which begins the menstrual phase again.

Question 31

Name the hormones that the ovaries produce

Answer 31

Estrogen and Progesterone

Question 32

What is the function of estrogen?

Answer 32

Significant in the production of eggs and the menstrual cycle. It is also responsible for secondary sex characteristics. These characteristics include enlarged breasts, widening of the pelvis, and a curvier figure as a result of fat deposits in the breast, hips, and buttocks.

Question 33

What does progesterone do?

Answer 33

It is necessary for the maintenance of pregnancy, but does not promote secondary sexual characteristics.

Question 34

What is the structure of the female breast?

Answer 34

it contains one to two dozen lobules, each with its own mammary duct which begins at the nipple and divides into numerous other ducts ending in blind sacs called alveoli. In a non-lactating breast, the ducts far outnumber the alveoli since alveoli are made up of cells that can produce milk.

Question 35

Is milk produced during pregnancy?

Answer 35

No it is not because the the hormone prolactin neededed for milk production is suppressed by estrogen and progesterone.

Question 36

When does milk production begin? What do the breasts produce prior to this ?

Answer 36

A few days after delivery, milk production begins prior to which the breasts produce a watery, yellowish-white fluid called colostrum, which has a similar composition to milk but contains more protein and less fat.

Question 37

What do the breasts produce prior to milk production after pregnancy?

Answer 37

Colustrum is a watery, yellowish-white fluid which has a similar composition to milk but contains more protein and less fat.

Question 38

When does pregnancy begin?

Answer 38

Pregnancy begins with fertilization of an egg by a sperm forming a zygote.

Question 39

How long are sperm viable for after ejaculation ?

How long can an egg survive after ovulation ?

Answer 39

Sperm are viable for 3-5 days after ejaculation, depending on the environment, and an egg can survive for up to 24 hours after ovulation.

Question 40

Based on sperm and egg viability after ejaculation and ovulation, respectively, when must copulation take place in order for fertilization to occur?

Answer 40

This means copulation must take place by one day after ovulation and can occur as early as two days before ovulation for fertilization to take place.

Question 41

Where does fertilization typically occur?

Answer 41

In the oviducts/fallopian tubes/uterine tubes.

Question 42

How does an egg in the fallopian tube attract sperm ?

Answer 42

The egg releases chemicals that attract the sperm

Question 43

What action does the sperm take upon reaching the egg?

Answer 43

When sperm reach the egg they release enzymes that break apart the corona radiate, follicle cells surrounding the egg. Once this is accomplished, more sperm release acrosomal enzymes that make a hole in the membrane of the egg, allowing the sperm to combine with the egg. When this union of egg and sperm occurs, the membrane of the egg changes chemically, preventing other sperm from penetrating the egg.

Question 44

Describe what happens after fertilization as the zygote travels to the uterus?

Answer 44

Frequent mitotic divisions occur on its way to the uterus.
The zygote spends about three to four days undergoing mitosis in the oviducts forming the morula and another three to four days undergoing mitosis while unattached in the uterus, forming the blastocyst as the endometrium prepares for implantation

Question 45

Why does the endometrium increase its blood supply and secrete glycogen during the menstrual cycle? What hormone causes this to occur?

Answer 45

To prepare for the implantation of the blastocyst and to sustain the blastocyst before it implants in the endometrium. Progesterone release from the corpus luteum causes this.

Question 46

Human Chorionic Gonadotropin - what is it ?

Answer 46

A hormone that is secreted by the blastocyst to stimulate the corpus luteum to secrete progesterone.

Question 47

How many days after fertiization does the blastocyst implant into the endometrium ?

Answer 47

The blastocyst implants into the endometrium of the uterus on day 7 at which time it begins to develop three layers: the ectoderm, the mesoderm, and the endoderm.

Question 48

What is the largest human cell in the body and the smallest ?

Answer 48

The largest is the female egg and the smallest is the male sperm.