Ch. 23- Prep for Exam

Select the structures that secrete hormones important in the maintenance of pregnancy.

-corpus luteum -placenta -trophoblast cells

How many chromosomes are contained in a secondary oocyte prior to fertilization?

23

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

6-7 days

What three fetal structures are no longer needed once the baby is born and breathing?

As soon as the baby is born, the foramen ovale, ductus arteriosus, ductus venosus, and umbilical vessels are no longer needed.

A secondary oocyte survives for about 24 hours after ovulation. Sperm cells are best able to fertilize an oocyte within 24-48 hours of ejaculation into the woman's body. Based on these timeframes, when would sexual intercourse have to take place in order for fertilization to occur?

Between 48 hours before and 24 hours after ovulation

What is the time frame of the neonatal period?

Birth to four weeks

At what stage of development does implantation occur?

Blastocyst

In what stage of postnatal development does a human take its first steps?

Childhood

Which of the embryonic membranes develops into the fetal portion of the placenta?

Chorion

What is the name of the thin, watery fluid secretion from the mammary glands that is rich in antibodies and is produced during the first days after birth?

Colostrum

Which of the following describes senescence?

Degenerative changes that occur with age

What term refers to the continuous process of change during the life of an individual?

Development

What fetal structure shunts blood between the pulmonary artery and aorta?

Ductus arteriosus

Match the fetal circulatory structure with its role in the fetal circulation.

Ductus arteriosus: Shunts blood from the pulmonary trunk to the aorta. Foramen ovale: Shunts blood from the right atrium into the left atrium. Ductus venosus: Carries oxygen- and nutrient-rich blood to the inferior vena cava, bypassing the liver. Umbilical vein: Carries oxygen- and nutrient-rich blood from placenta to fetus. Umbilical artery: Carries oxygen-poor blood from fetus to placenta.

Secretion of human chorionic gonadotropin (hCG) occurs during what time frame during pregnancy?

During early pregnancy, through the fourth month

Which primary germ layer gives rise to many of the mucous membranes, including those of the digestive tract, respiratory tract, and urethra?

Endoderm

Name the hormone secreted during pregnancy that, when at high levels, causes the ducts of the mammary glands to grow and branch.

Estrogen

Name the process that is illustrated in this figure.

Fertilization

What term describes the union of a sperm cell with a secondary oocyte?

Fertilization

What term describes an increase in the size of a structure due to increase in the number and size of cells?

Growth

Complete the sentences describing different types of twins.

If two secondary oocytes are ovulated during one cycle and both are fertilized, the resulting offspring are called fraternal twins. Another term is dizygotic twins, in reference to the number of zygotes formed. If two inner cell masses form within a single blastocyst, each producing an embryo, the resulting offspring are identical twins. Since they arise from one zygote, they are also referred to as monozygotic twins.

What is the name of the stage of development that occurs from four weeks to one year old?

Infancy

What developmental structure forms the primary germ layers during the embryonic stage?

Inner cell mass

What is the placental membrane and what is its role?

Layer through which nutrients and gases are exchanged between embryonic and maternal blood

What percentage of sperm deposited in the vagina reach the secondary oocyte?

Less than 1%

What is the last primary germ layer to form?

Mesoderm

What is the most immediate need of a newborn?

Obtain oxygen

What hormone stimulates uterine contractions during labor?

Oxytocin

Oxytocin is a hormone involved in labor and delivery and the functioning of the mammary glands. What endocrine gland secretes oxytocin?

Posterior pituitary

What is the function of hCG (human chorionic gonadotropin)?

Prevents the corpus luteum from degenerating

What hormone stimulates the production of milk in the mammary glands?

Prolactin

What chemical stimulates the sperm's tail movement for propulsion through the uterus and uterine tube?

Prostaglandin

Which hormone could be used to induce labor?

Prostaglandin

What hormone is released from the corpus luteum that allows greater movement at the pubic symphysis and sacroiliac joints as the time of birth approaches?

Relaxin

Fetal hemoglobin has greater attraction (affinity) for oxygen than does adult hemoglobin.

TRUE

Complete the sentences describing the time frame that fetal structures are at high risk for birth defects.

The embyro first becomes susceptible to nutitional inadequacies at the third week. The CNS is at high risk from the 3rd to the 16th week. The eye is at high risk from 4th to the 8th week. The heart is at high risk from the 3rd to the 6th week. The palate is at high risk from the 6th to 9th week.

Why is a newborn at risk for dehydration and electrolyte imbalance?

The kidneys are unable to concentrate urine.

What is the amniochorionic membrane?

The membrane formed by the fusion of the chorion and amnion

Why does the first breath of a newborn need to be a forceful breath?

The newborn's lungs are collapsed.

Complete the following sentences describing the transport of sperm in the female reproductive tract prior to fertilization.

The sperm must travel to the uterine tubes where fertilization will take place. The journey is aided by several factors. The uterus and cervix contain a thin, watery secretion that promotes sperm transport. This secretion is produced in response to the hormone(s) estrogens. Lashing of the sperm tails is stimulated by prostaglandins in the semen. This chemical also stimulates contractions in the uterus anduterine tubes. Against all odds, out of the 200-600 million sperm initially deposited, only a few hundred sperm make it to the oocyte.

Fill in the Blank

The time from fertilization to birth is called the prenatal period and the time after birth is called the postnatal period.

Complete the sentences about fetal circulation. Then arrange the sentences in logical order, following the flow of blood from the placenta, through the circulation, and back to the placenta.

The umbilical vein transports oxygen-rich blood to the liver and the ductus venosus, a vessel that bypasses the liver. The bypass drains into the inferior vena cava where it mixes with oxygen-poor blood, before entering the heart. Most blood from the right atrium is shunted into the left atrium through the foramen ovale. If blood does travel into the right ventricle, the blood can be shunted from the pulmonary trunk to the aorta through the ductus arteriosus. Blood then travels through the aorta to the umbilical artery which brings the blood to the placenta for oxygenation.

Complete the sentences describing growth and development.

The uniting of an egg and sperm is known as fertilization. The process of growth involves an increase in the number and size of cells. During the process of development, the organism changes in appearance as it moves through the phases of life. Both of these processes are prominent from the time of fertilization to birth, known as the prenatal period, and in the postnatal period, which begins with birth and ends with death.

Which of the following are the extra-embryonic membranes?

They are the YOLK SAC, the ALLANTOIS, the AMNION, and the CHORION.

The figure shows an alveolar gland. What is the function of the pink cells indicated by the arrows?

To eject milk into ducts

What group of cells within a zygote are involved in the formation of the placenta?

Trophoblast

Which vessel carries oxygen-rich blood from the placenta to the fetus?

Umbilical vein

Which of the following describes the path of sperm cells, from ejaculation to the egg cell?

Vagina; cervix; uterus; uterine tube

What is the correct sequence of stages during the cleavage period?

Zygote, morula, blastocyst, embryo

Passive Aging

a breakdown of structures and slowing of functions.

At what point does an embryo become a fetus?

at about 8 weeks of development

The developing embryo goes through a stage in which it is a hollow ball of cells. This hollow ball of cells is called a(n) __________.

blastocyst

What maternal structure helps form the placenta?

decidua basalis

The process of __________ involves the movement of embryonic cells to form a mesoderm between the ectoderm and endoderm layers of cells.

gastrulation

The hormone __________ suppresses uterine contractions. The hormone __________ stimulates uterine contractions.

progesterone; prostaglandin

Active Aging

the appearance of new substances or new activities.

Life Span

the length of time that a human can theoretically live

Life Expectancy

the realistic projection of how long an individual will live

The product of fertilization is called a(n) __________.

zygote

Upon the mingling of the pronuclei in a fertilized oocyte, the cell is now called a(n) __________.

zygote