Pregnancy and Lactation Flashcards - Guyton Physiology Chapter 82

If the ovum becomes fertilized, a new sequenceof events called <?> takes place.

gestation orpregnancy

In the ovary, the ovum is in whatstage? primary oocyte

When does the next division takeplace?

shortly beforeovulation

What type of division does theprimary oocyte undergo? mieosis

What does the primary oocyteturn into? secondary oocyte

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What is expelled from the nucleusof the primary oocyte? First polar body

What is the amount of geneticcontent in a primary oocyte?

23 pairedchromosomes

What is the amount of genetic content in asecondary oocyte?

23 unpairedchromosomes

Where does the ovum enter thesecondary oocyte stage?

In the ovary. Expelled shortlyafter.

Secondary oocyte is expelled fromthe ovary into? abdominal cavity


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granulosa cells around the ovumare called corona radiata

The inner surfaces of the fimbriated tentacles ofthe fallopian tubes are are lined with ciliated epithelium

cilia of the fallopian tubes areactivated by estrogen from the ovaries

openning of the fallopian tubealso called ostium

Percentage of ovum that fail to make it intofallopian tubes 2%


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After male ejaculation, how long does it take forsperm to reach ampullae? 5-10 min

Transport of the sperm is aided by contractionsof the uterus and fallopian tubes stimulated by:

(1) Prostaglandins in the male seminal fluid and(2) Oxytocin released from the posterior pituitary

gland of the female during her orgasm"

Fertilization of the ovumnormally takes place where? ampulla

Upon fertilizing the cell, the head of the malesperm becomes what structure? Male pronucleus

When is the second polar bodyexpelled?

Once a sperm has entered the ovum and theoocyte divides again to form the mature ovum.


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blastocyst # of cells fertilized ovum of about 100 cells

days normally required for transport of thefertilized ovum through the remainder of the

fallopian tube into the cavity of the uterus 3 to 5

define: isthmus last two cm before the tube entersthe uterus

when is the isthmus is spasticallycontracted? first 3 days after ovulation

Why does the isthmus eventuallyrelax?

the rapidly increasing progesterone secreted bythe ovarian corpus luteum first promotesincreasing progesterone receptors on the

fallopian tube smooth muscle cells; then theprogesterone activates the receptors, exerting a

tubular relaxing effect


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Dividing ovum is at what stagewhen entering the uterus? blastocyst

How many days is blastocyst in the uterine cavitybefore implantation? 1-3 days

blastocyst obtains its nutritionfrom?

the uterine endometrial secretions, called"uterine milk."

cells that develop over the surfaceof the blastocyst trophoblast cells

function of trophoblast cells

(1) Promote implantation - Secrete proteolyticenzymes that digest and liquefy the adjacent cells

of the uterine endometrium

(2) Nutrition transportation


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What determines the sex of thefetus

Presence of X or Y chromosomein sperm

During the latter half of each monthly sexualcycle, which cells turn into large swollen cells

con- taining extra quantities of glycogen,proteins, lipids, and even some minerals

necessary for development of the conceptus?

endometrial stromal cells

When the conceptus implants in theendometrium, the endometrial cells turn into decidual cells

Difference between decidual cellsand endometrial cells

decidual cells contain morenutrients and are more swollen.

What hormone induces thedevelopment decidual cells?

continued secretion ofprogesterone


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Source of nutrients during firstweek Decidua

Source of nutrients switches completely toplacenta after how many days about 16

Blood begins to be pumped by the embyo's hearthow many days after fert.? 16

Projections sent out by thetrophoblast are called placental villi

what grows in placental villi? fetal capillaries


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How many arteries/veins are inthe fetal umbilical cord?

2 fetal umbilical arteries, 1 fetalumbilical vein

What is the name of the structure providingoxygenated blood from the placenta to the fetus? Umbilical vein

pockets of blood surrounding villiin the placenta maternal sinuses

provide oxygenated blood to theplacenta uterine arteries

eliminate deoxygenated bloodfrom the placenta uterine veins


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In the early months of pregnancy, the placentalmembrane has a high/low permeability?

Low permeability - due tounderdeveloped and thick

placenta

The dissolved oxygen in the blood of the largematernal sinuses passes into the fetal blood by:active transport / facilitated diffusion / simple

diffusion?simple diffusion

Occasionally, "breaks" occur in the placentalmembrane and cause?

fetal blood cells to pass into the mother or, evenless commonly, the mother's cells to pass into the

fetus

Near the end of pregnancy, the mean PO2 of themother's blood in the placental sinuses is?

about 50 mmHg

the mean PO2 in the fetal blood after it becomesoxygenated in the placenta is 30 mm Hg


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the mean pressure gradient for diffusion ofoxygen through the placental membrane is 20 mm Hg

How is 20 mm Hg enough forfetal blood oxygenation?

(1) Fetal Hb greater affinity for O2(2) [Hb] 50% greater in fetus than mother

(3) Double Bohr effect - hemoglobin can carrymore O2 at a low PCO2 than it can at a high

PCO2. Fetal blood dumps large amounts of CO2into maternal circulation [causing high PCO2 in

mother, low PCO2 in fetus].

Compare PCO2 of fetal blood tomaternal blood

PCO2 of the fetal blood is 2 to 3 mm Hg higherthan that of the maternal blood

Compare CO2 solubility to O2solubility

Extreme solubility of carbon dioxide in theplacental membrane allows carbon dioxide todiffuse about 20 times as rapidly as oxygen.

In the later stages of pregnancy, what kind oftransport is employed to meet the fetus's higher

demands for glucose?Facilitated diffusion


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What other substances diffuse with relative easefrom maternal blood to fetal blood?

Substances as ketone bodies and potassium,sodium, and chloride ions diffuse with relative

ease from the maternal blood into the fetal blood.

Which of the three high concentration wasteproducts (urea, uric acid, and creatinine) are

significantly higher in the fetus than in maternalblood?

creatinine (does not diffuse through the placentalmembrane easily)

Hormones at high levels during apregnancy

(1) human chorionic gonadotropin(2) estrogens

(3) progesterone(4) human chorionic somatomammotropin

Menstruation normally occurs in a nonpregnantwoman about how many days after ovulation? 14 days

Menstruation is prevented by theproduction of HCG


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Which cells secreteHCG?

syncytial trophoblast cells

When can HCG be detected? 8 to 9 days after ovulation, shortly after theblastocyst implants in the endometrium

Function of HCGPrevents involution of the corpus luteum at theend of the monthly female sexual cycle. Causes

the corpus luteum to secrete even largerquantities of its sex hormones—progesterone

and estrogens

If the corpus luteum is removed beforeapproximately the 7th week of pregnancy, what is

the result?

Spontaneousabortion

When does the corpus luteuminvolute during pregnancy?

The corpus luteum involutes slowly after the 13thto 17th week of gestation.


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Effect of Human ChorionicGonadotropin on the Fetal

Testes.

interstitial cell-stimulating effect on the testes,resulting in the production of testosterone in the

male fetus

Placenta secretes whathormones? Estrogen and progesterone

Which cells of the placentaproduce hormones? syncytial trophoblast cells

How are hormones produced bythe placenta?

from dehydroepiandrosterone and 16-hydroxydehydroepiandrosterone, which are

formed both in the mother's adrenal glands andin the adrenal glands of the fetus

Fuctions of estrogen duringpregnancy

(1) enlargement of the mother's uterus, (2)enlargement of the mother's breasts and growth

of the breast ductal structure, and (3)enlargement of the mother's female external

genitalia (4) relax the pelvic ligaments


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Functions of progesterone duringpregnancy

"(1) development of decidual cells in the uterineendometrium

(2) decreases the contractility of the pregnantuterus

(3) contributes to the development of theconceptus even before implantation

(4) helps the estrogen prepare the mother'sbreasts for lactation"

human chorionic somatomammotropin begins tobe secreted how many weeks into the pregnancy? 5 weeks

Pituitary gland during pregnancyenlarges at least 50 per cent during pregnancy

and increases its production of corticotropin, thy-rotropin, and prolactin

Reason for increased water/salt retention andpregnancy-induced hypertension aldosterone

hormone released for Calcium recapturing frommother's bones to provide fetus (and new born

baby) with Ca++ for bone growthparathyroid hormone


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affect of pregnancy onmetabolism increase

average lbs gained by pregnantwoman 24 lbs

Vitamin that assists in Ca++absorbtion in the GI tract vitamin D

Shortly before birth of the baby, which vitamin isoften added to the mother's diet so that the baby

will have sufficient prothrombin to preventhemorrhage, particularly brain hemorrhage,

caused by the birth process.

Vitamin K

at the time of birth of the baby, the mother hashow many liters of extra blood in her circulatory

system? 1-2 L


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Mother's cardiac output during pregnancy is howmuch above normal?

30 to 40 % above normal by the27th week of pregnancy

Maternal respiration shortly before birth is howmuch above normal? 20% above normal

volume of amnioticfluid

between 500 milliliters and 1 liter

water in amniotic fluid isreplaced how often?

once every 3 hours, and the electrolytes sodiumand potassium are replaced an average of once

every 15 hours.

rapid rise in arterial blood pressure tohypertensive levels during the last few months of

pregnancy associated with leakage of largeamounts of protein into the urine is called?

preeclampsia or toxemia ofpregnancy


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Birth of the baby is also called: Parturition

What are two major categories of effects that leadup to the intense contractions responsible for

parturition

(1) progressive hormonal changes that causeincreased excitability of the uterine musculature,

and (2) progressive mechanical changes.

Hormonal Factors That IncreaseUterine Contractility

(1) Increased Ratio of Estrogens to Progesterone.(2) Effect of Oxytocin on the Uterus.

(3) Effect of Fetal Hormones on the Uterus.

Mechanical Factors That IncreaseUterine Contractility

(1) Stretch of the Uterine Musculature.(2) Stretch or Irritation of the Cervix.

Twins are born (on average) how many daysearlier than a single child? 19 days earlier


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Periodic episodes of weak and slow rhythmicalcontractions during most months of pregnancy

are called?Braxton Hicks contractions


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Pregnancy and Lactation Flashcards - Guyton Physiology Chapter 82