Pregnancy and Human Development

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Which of the following is not a correct matching of a fetal structure with what it becomes at birth?

DUCTUS ARTERIOSUS-LIGAMENTUM TERES
foramen ovale-fossa ovalis
umbilical arteries-medial umbilical ligament
ductus venosus-ligamentum venosum

What does the foramen ovale become at birth?

fossa ovalis

T OR F: An episiotomy is an incision made to widen the vaginal orifice, aiding fetal expulsion.

TRUE

Onset of labor may be a result of all of the following factors except ________.

ASPIRIN AND SIMILAR DRUGS
secretion of oxytocin
contraction-related increased emotional and physical stress
high estrogen levelS

Relaxin is a hormone produced by the placenta and ovaries. The function of this hormone is to ________.

relax the pubic symphysis

Derivatives of the mesoderm include ________.

endothelium of blood and lymph vessels

Derivatives of the endoderm include ________.

epithelium of the respiratory tract

Derivatives of the ectoderm include ________.

epithelium of the pituitary and pineal glands

Which of the following is true in reference to what may pass through the placental barriers?

nutrients, respiratory gases, wastes, and alcohol

Which hormone is not produced by the placenta?

human placental lactogen
human chorionic thyrotropin
INHIBIN
relaxin

The placenta is formed by ________.

maternal and fetal tissues

This cord attaches the embryo to the placenta.

umbilical cord

During the process of implantation, the inner cell mass (ICM) gives rise to three embryonic membranes. Which of the following is not one of these membranes?

amnion
yolk sac
allantois
CHORION

All exchanges between mother and embryo occur ________.

across the chorionic membrane

In the human, this germ cell layer gives rise to many of the organ systems, including the skeleton, skeletal muscles, walls of GI organs, urinary system, and circulatory system.

mesoderm

The three primary germ layers develop during this stage of human fetal development.

gastrula

The blastocyst, or ________, consists of two distinct populations of cells.

chorionic vesicle

Once fertilization has occurred, the activities of development begin. The first such activity is ________.

an increase in cell number

Name the blood vessel that carries oxygen-rich blood to the fetus.

umbilical vein

In what region of the uterus does implantation usually occur (as indicated by the position of the placenta)?

in the upper part of the uterus

During the ________ stage of development, the human embryo implants in the uterine wall.

blastula

The blastocyst, or ________, consists of two distinct populations of cells.

chorionic vesicle

The function of cleavage is to ________.

increase the number of cells forming the blastocyst

The human blastocyst consists of two populations of cells with different functions. Select the correct match between population and its function.

inner cell mass (ICM); forms the embryo and three of the four extraembryonic membranes

Implantation of the blastocyst in the uterine wall is complete by day ________ after ovulation.

14

The trophoblast cells of the blastocyst form the ________, which extends elaborate villi into the blood-filled sinusoids of the uterine wall.

chorion

Chorionic villi look like ________.

feathery extensions of the chorion in the uterine wall

What organs appear very early in development?

brain and heart

Development progresses ________.

in rostral to caudal and proximal to distal directions

What is true of the structure of the human placenta?

It is disc-shaped.

A 30-year-old woman is admitted to the emergency room. Her husband, who rode in the ambulance with her, said that she had suddenly complained of severe pain in the right iliac region of her abdomen and then had collapsed. Upon examination, she was shown to have signs of internal hemorrhage and her abdominal muscles were rigid. Her menstrual history revealed that she had missed her last menstrual period. A diagnosis of ruptured tubal, or ectopic, pregnancy was made and surgery scheduled. What is an ectopic pregnancy, and why is it problematic?

In an ectopic pregnancy, the embryo implants in any site other than the uterus. It is problematic because it is unable to establish a placenta or accommodate growth, and could cause the uterine tube to rupture.

Mrs. Phang, eight months pregnant with her first child, makes an appointment with her obstetrician to investigate the cause of vaginal bleeding. Because it is actually more "spotting" than frank bleeding, and painless, she is becoming worried. Ultrasound visualization of her abdomen shows that the placenta is formed across the internal os of the cervix, and she is ordered to her bed for the remainder of the pregnancy. What name is given to Mrs. Phang's condition? Why is it an extremely serious condition?

The condition is called placenta previa. It is an extremely serious condition because stretching of the uterus and cervix could cause tearing of the placenta.

T OR F: Conceptus is a term used to describe the developing human offspring.

TRUE

T OR F: The period from fertilization through week eight is called the embryonic period.

TRUE

T OR F: Fertilization occurs while the egg is still in the ovarian follicle.

FALSE

T OR F: Freshly deposited sperm are not capable of penetrating an oocyte.

TRUE

T OR F: The embryonic stage lasts until the end of the eighth week.

TRUE

T OR F: A zygote is usually formed within the uterus.

FALSE

The result of polyspermy in humans is ________.

a nonfunctional zygote

It is impossible for sperm to be functional (able to fertilize the egg) until after ________.

they undergo capacitation

Proteases and acrosin are enzymes. How do they function in reproduction?

They act to break down the protective barriers around the egg, allowing the sperm to penetrate.

They act to break down the protective barriers around the egg, allowing the sperm to penetrate.

zygote, morula, blastocyst

Select the correct statement about fertilization.

Millions of sperm cells are destroyed by the vagina's acidic environment.

Sperm move to the uterine tube through uterine contractions and the energy of their own flagella. What other factor is involved in sperm movement?

reverse peristalsis of the uterus and uterine tubes

Cleavage as part of embryonic development is distinctive because it involves ________.

cell division by mitosis with little or no growth between successive divisions

Which of the following statements about the events of fertilization is not true?

The secondary oocyte completes the second meiotic division.
THE TWO PRONUCLEI DIVIDE.
The head of the sperm forms the male pronucleus.
Proteases and acrosin proteinases of the sperm disperse the cells of the corona radiata of the oocyte.

Describe the events of the oocyte from sperm penetration to first cleavage.

After sperm penetration, the oocyte completes meiosis II and releases the second polar body. The two nuclei swell into pronuclei and join each other to form a zygote. The cell then undergoes its first mitosis and cell division to form two daughter cells.

Describe the events allowing monospermy.

A sperm entering the oocyte causes ionic calcium to be released into the oocyte cytoplasm, activating the oocyte and preparing it for cell division. This also causes the cortical granules to spill their contents into the extracellular space beneath the zona pellucida. Enzymes from the cortical granulus destroy sperm receptors, preventing further sperm entry. This spilled material binds with water, and as it swells, detaches all sperm still in contact with the oocyte membrane.

When do we begin to call the developing individual a fetus rather than an embryo?

We begin to call the developing individual a fetus at the beginning of the ninth week.

After the egg is fertilized, it is called a(n) ________.

zygote

_____________ extends from the last menstrual period until birth, approximately 280 days.

A gestation period

The fertilized egg is known as the ____________.

zygote

Which of the following is not an extraembryonic membrane that forms during the first two to three weeks of development?

Amnion
Allantois
Yolk sac
GASTRULA

Sperm freshly deposited in the female vagina are incapable of fertilizing an egg. What must happen first?

capacitation

T OR F: By 72 hours after fertilization, the egg has divided into more than 160 cells and is called the morula.

FALSE

T OR F: Implantation begins six to seven days after ovulation.

TRUE

T OR F: A pregnancy test involves antibodies that detect GH levels in a woman's blood or urine.

FALSE

T OR F: The "fluid-filled, hollow ball of cells" stage of development is the blastocyst.

TRUE

T OR F: A blastocyst is a hollow ball of cells, while the morula is a solid ball of cells.

TRUE

Estrogen and progesterone maintain the integrity of the uterine lining and prepare the mammary glands to secrete milk. Which of the following structures makes this possible during the first three months of pregnancy?

corpus luteum

The placenta, a vitally important metabolic organ, is made up of a contribution from mother and fetus. Which portion is from the fetus?

chorion

Which hormone maintains the viability of the corpus luteum?

human chorionic gonadotropin

Implantation involves ________.

embedding of the blastocyst in the uterine wall

Initially, the implanted embryo obtains its nutrition by ________.

digestion of endometrial cells

Shortly after implantation ________.

the trophoblast forms two distict layers

The trophoblast is mostly responsible for forming the ________.

placental tissue

Which hormone is not produced by the placenta?

human placental lactogen
relaxin
human chorionic thyrotropin
INHIBIN

Implantation of the blastocyst is the result of all of the following except ________.

PHAGOCYTOSIS BY THE TROPHOBLAST CELLS
adherence of the trophoblast cells to the endometrium
proteolytic enzymes produced by the trophoblast cells
settling of the blastocyst onto the prepared uterine lining

Which of the choices below occurs if fertilization of the ovum occurs and implantation takes place?

The corpus luteum is maintained until the placenta takes over its hormone-producing functions.

The decidua basalis is ________.

located between the developing embryo and the myometrium

At what time in the pregnancy is the placenta fully prepared to fulfill the needs of the developing fetus?

The placenta is fully formed and functional as a nutritive, respiratory, excretory, and endocrine organ by the end of the third month of pregnancy.

Briefly describe the events leading to the implantation of the blastocyst in the uterus, including how it is nourished.

The blastocyst floats freely in the uterine cavity for three or four days, during which time it is nourished by uterine secretions. Six days after ovulation, implantation begins. The trophoblast determines the readiness of the endometrium for implantation. If the mucosa is prepared for implantation, the blastocyst becomes embedded high in the uterus.

The ________ cells of the blastocyst will take part in placental formation.

trophoblast

Which cells invade the endometrium, digesting the uterine cells they contact, so that implantation of the blastocyst can occur?

syncytial trophoblast cells

Which of the following is not a primary germ layer?

Endoderm
GASTRODERM
Ectoderm
Mesoderm

Which of the following is the primary germ layer that forms the basis for the digestive, respiratory, and urogenital systems, and associated glands?

endoderm

Which of the following is the correct sequence of development from zygote to embryo?

cleavage, morula, blastocyst, gastrula

What structure(s) ultimately form(s) the placenta?

decidua basalis and chorionic villi

T OR F: Of the three germ layers, the mesoderm forms the most body parts.

TRUE

T OR F: The embryo is directly enclosed in and protected by the amnion.

TRUE

T OR F: In fetal circulation, one way in which blood bypasses the nonaerated lungs is by way of the foramen ovale.

TRUE

Cells on the dorsal surface of the two-layered embryonic disc migrate to form a raised groove known as the ________.

primitive streak

Which of the following is not a germ layer?

EPIDERM
mesoderm
endoderm
ectoderm

The formation of endodermal and ectodermal germ layers occurs at ________.

gastrulation

The umbilical arteries carry ________.

waste products to the placenta

The dorsal surface cells of the inner cell mass form ________.

the primitive streak

Muscle tissue is formed by the ________.

mesoderm

Neural tissue is formed by the ________.

ectoderm

Which of the following is not usually considered a teratogen?

ASPIRIN
wine
German measles
thalidomide

Derivatives of the ectoderm include ________.

epithelium of the pineal and pituitary glands

Derivatives of the mesoderm include ________.

endothelium of blood and lymph vessels

Derivatives of the endoderm include ________.

epithelium of the respiratory tract

Select the correct statement about the special fetal blood vessels.

The umbilical vein becomes the ligamentum teres.

How are the metabolic needs of the implanted embryo provided for?

Initially, the implanted embryo obtains nutrition by digesting the endometrial cells, but by the second month, the placenta is providing all the nourishment and oxygen the embryo requires. The placenta is also responsible for disposing of embryonic metabolic wastes.

The ________ stage of development is the first in which all three germ layers of tissue are evident.

gastrula

________ is a tissue with star-shaped cells that are free to migrate widely throughout the embryo.

Mesenchyme

Neural tissue develops from the ________.

ectoderm

What embryonic structure is the structural base for the umbilical cord?

allantois

The first axial support for the embryo is called the ________.

notochord

The foramen ovale and the ductus arteriosus are both examples of:

pulmonary bypass shunts, which serve to bypass the lungs.

Which of the following occurs 21-30 weeks into pregnancy, during the fetal period?

The eyes are open.

Which of the following occurs 9-12 weeks into pregnancy, during the fetal period:

Sex is readily detected by observing the genitals.

A dangerous complication of pregnancy called ____________ results in an insufficient placental blood supply, which can starve a fetus of oxygen. The pregnant woman becomes edematous and hypertensive, and proteinuria occurs.

preeclampsia

Which of the following is the longest stage of labor, lasting 6-12 hours or more?

dilation stage

Which of the following INCORRECTLY matches an embryonic structure with its function?

allantois/serves as the structural basis for the umbilical cord
YOLK SAC/PROVIDES NUTRIENTS TO DEVELOPING EMBRYO
chorion/forms baby's part of placenta
amnion/protects embryo against physical trauma and helps maintain homeostatic temperature

Which of the following is NOT a primary germ layer from which all body organs derive?

ectoderm
MESENCHYME
endoderm
mesoderm

Which of the following structures is derived from the ectoderm?

brain and spinal cord

_____ is protective water-filled sac surrouding the embryo.

Amnion

_____ is extraembryonic membrane that develops from the trophoblast and some extraembryonic mesoderm, and forms part of the placenta.

Chorionic villus

_____ is site of early blood cell production and forms part of the gut (digestive tube).

Yolk sac

____ is part of the endometrium that destined to be a part of the placenta.

Decidua basalis

____ is part of the endometrium that surrounds the uterine cavity face of the implanted embryo.

Decidua capsularis

T OR F: The body systems of the developing embryo are present in at least rudimentary form at eight weeks.

TRUE

Developmental events during weeks 9-12 include ________.

sex readily detected from the genitals

T OR F: In humans, zonal inhibiting proteins destroy sperm receptors, preventing polyspermy.

TRUE

T OR F: While human chorionic gonadotropin levels spike and sharply decline to reach a low value by 4 months, estrogen and progesterone levels steadily increase over the course of the pregnancy.

TRUE

At what period of fetal development are all body systems present in at least rudimentary form?

8 weeks post fertilization

T OR F: A pregnant woman urinates more often than usual because the uterus compresses the bladder, and she must also dispose of fetal metabolic wastes.

TRUE

Relaxin is a hormone produced by the placenta and ovaries. The function of this hormone is to ________.

relax the pubic symphysis

Briefly describe the physiological changes occurring in the mother during pregnancy.

Many women suffer nausea until their systems become adjusted to elevated levels of estrogen and progesterone. Heartburn is common due to displacement of the esophagus and crowding of the stomach by the growing fetus in the uterus. Additional wastes from fetal metabolism cause the production of more urine. Due to pressure on the bladder by the uterus, urination is more frequent. Tidal volume increases during pregnancy, as does respiratory rate. Residual volume decreases and many women exhibit dyspnea. Total body water rises, acting as a safeguard against blood loss during birth. Blood volume increases, blood pressure and pulse rise, and cardiac output increases.

T OR F: The sole responsibility of the placenta is to supply the fetus with oxygen and nutrients.

FALSE

Which body system of a pregnant woman shows the most dramatic physiological changes during pregnancy?

Cardiovascular system

A 19-year-old, single, sexually active college student, who has not used birth control on a regular basis, is in her first trimester of pregnancy. She is at the OB/GYN clinic for her first prenatal visit. In assessing her nutrition, the nurse discovers that the patient drinks heavily on a regular basis, and also states that she does not like milk. What information should the nurse give the patient regarding nutrition?

ALL OF THESE ANSWERS ARE CORRECT.
The nurse should inform the patient to take multivitamins containing folic acid to reduce the risk of birth defects.
The patient should increase her daily calorie intake by 300 calories to sustain proper fetal growth.
The nurse should warn the patient that alcohol can cause serious permanent damage to the fetus.

The patient is in her first trimester of pregnancy. She complains of feeling nauseated and has vomited on occasion. She tells the nurse that she did not have this with her first pregnancy. She asks the nurse, "What is causing this and when will it end?" How should the nurse respond?

The nausea is caused by elevated levels of progesterone and estrogen, and the nausea should end once her body adjusts to the increased hormone levels.

T OR F: An episiotomy is an incision made to widen the vaginal orifice, aiding fetal expulsion.

TRUE

T OR F: The placenta and its attached fetal membranes are collectively called the afterbirth.

TRUE

T OR F: Human placental lactogen initiates labor.

FALSE

Onset of labor may be a result of all of the following factors except ________.

high estrogen levels
ASPIRIN AND SIMILAR DRUGS
contraction-related increased emotional and physical stress
secretion of oxytocin

At which stage of labor is the "afterbirth" expelled?

placental

During which stage of labor is the fetus delivered?

expulsion

Define Braxton-Hicks contractions.

Braxton-Hicks contractions are the weak, irregular uterine contractions resulting from the increase in estrogen production. Estrogen causes oxytocin receptors to form on the myometrial cells of the uterus and antagonizes progesterone's quieting influence on the uterine muscle. As a result, the myometrium becomes increasingly irritable, resulting in weak, irregular contractions.

List four factors that help to precipitate parturition.

Four factors that help to precipitate parturition include: (1) estrogen peaks to its highest levels in the mother's blood, causing irregular uterine contractions due to oxytocin and negation of progesterone's influence on the uterine muscle; (2) prostaglandins are stimulated by the increase in oxytocin to act as uterine muscle stimulants; (3) increasing emotional and physical stressors activate the mother's hypothalamus, which signals oxytocin release; and (4) certain cells of the fetus begin to produce oxytocin, which in turn acts on the placenta, stimulating production and release of prostaglandins.

The act of giving birth is called ________.

parturition

T OR F: The first major event in organogenesis is neurulation.

TRUE

In which stage of labor does crowning occur?

expulsion

A 28-year-old woman has been in the first stage of labor for several hours. Her uterine contractions are weak, and her labor is not progressing normally. Because the woman insists upon a vaginal delivery, the physician orders that pitocin (a synthetic oxytocin) be infused. What will be the effect of pitocin?

Pitocin will act on the placenta to release prostaglandins and will also act directly on the uterine wall to cause muscle contractions.

T OR F: Surfactant production in premature infants is rarely a factor in providing normal respiratory activity.

FALSE

Which of the following is not a correct matching of a fetal structure with what it becomes at birth?

foramen ovale-fossa ovalis
DUCTUS ARTERIOSUS-LIGAMENTUM TERES
ductus venosus-ligamentum venosum
umbilical arteries-medial umbilical ligament

Which of the following is not assessed as part of the Apgar score?

muscle tone
heart rate
TEMPERATURE
respiration

The cardiovascular system of a newborn must be adjusted after the infant takes its first breath. Which of the following is also true?

The ductus arteriosus constricts and is converted to the ligamentum arteriosum.

Explain what triggers a baby's first breath.

A buildup of carbon dioxide in the baby's blood once the carbon dioxide is not being removed by the placenta causes acidosis. This excites respiratory control centers in the baby's brain and triggers the first inspiration.

What does the foramen ovale become at birth?

Fossa ovalis

Milk ejection or letdown reflex is stimulated by which of the following hormones associated with pregnancy?

oxytocin

Hormones concerned with events of lactation include ________.

oxytocin

The first "milk" the mother produces is called ________.

colostrum

As the newborn suckles, the mother's pituitary produces ________ to assist in producing milk.

prolactin

A mother who has been nursing her infant for over seven months is beginning to have problems throughout the day with nausea. What might explain the nausea?

The mother was not taking birth control pills because she assumed that she could not get pregnant while nursing. This mother is probably pregnant again.

The lactation nurse visits a first-time mother six hours after her delivery of a healthy 8-pound boy. The patient is giving the baby boy a bottle of sugar water. She tells the lactation nurse that she does not seem to be producing milk. What should the nurse say to the patient?

True milk production will not start until two to three days after birth. During this delay, colostrum is produced. Continual milk production depends on mechanical stimulation of the nipples, normally provided by the suckling infant.

Which of the following is a highly unlikely method of producing a child?

embryo transfer
in vitro fertilization
ECTOPIC IMPLANTATION
gamete intrafallopian transfer

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