Pregnancy

Question 1

When and where is the usual site of fertilization?

Answer 1

usually occurs in upper ⅓ of oviduct, typically within 24 hours after ovulation (sperm cells can actually survive up to five days in female reproductive tract)

Question 2

What is a zygote?

Answer 2

fertilized ovum

Question 3

What do zygotes undergo?

Answer 3

rapid mitotic divisions

• after 3 days, morula (solid ball of cells) is formed
• morula reaches uterus on day 4
• over the next two days, morula develops into blastocyst (hollow ball with inner cavity known as blastocoel) that is ready to be implanted in uterine wall

Question 4

What is a trophoblast?

Answer 4

outer layer of blastocyst cells responsible for providing nutrients to developing embryo

Question 5

What is the inner cell mass?

Answer 5

cluster of cells at one end of blastocyst that will form the embryo itself

Question 6

What does the trophoblast secrete?

Answer 6

• enzymes involved in implantation

- hormone hCG that maintains CL

Question 7

Why does trophoblast secrete enzymes?

Answer 7

enzymes digest proteins on uterine lining – which carves hole in endometrium for implantation

Question 8

Why does trophoblast secrete human chorionic gonadotropin (hCG)?

Answer 8

absolutely essential for success of pregnancy as it maintains functional CL in ovary until placenta takes over steroid hormone production at end of first trimester

Question 9

What do pregnancy tests detect?

Answer 9

presence of hCG in urine

Question 10

What does high concentration of progesterone produced by CL do?

Answer 10

prevents myometrial (uterine muscle) contractions that would expel the newly implanted blastocyst

Question 11

What does high concentration of estrogen produced by CL do?

Answer 11

maintains functional uterine lining, which is critically important for successful implantation

Question 12

How is trophoblast involved with placenta?

Answer 12

trophoblast constitutes fetal part in developing placenta

Question 13

What does placenta allow?

Answer 13

exchange of nutrients and metabolic wastes between maternal and fetal blood

Question 14

What is the placenta formed by?

Answer 14

interlocking maternal and fetal structures

Question 15

What are the fetal structures involved in forming placenta?

Answer 15

• placental villi
• finger-like projections that protrude into pools of maternal blood within intervillus spaces that are supplied by maternal arterioles

Question 16

How does fetal blood continuously flow between placental villi and fetal circulation?

Answer 16

by means of umbilical artery and vein found within umbilical cord

Question 17

What occurs as maternal blood percolates through intervillus spaces?

Answer 17

it exchanges oxygen, nutrients and fetal metabolic wastes with fetal blood in villi, and then exits through uterine vein

Question 18

What are hormones secreted by the placenta important for?

Answer 18

maintenance of pregnancy

Question 19

What are the hormones secreted by placenta? (5)

Answer 19

• hCG
• E
• P
• human placental lactogen (hPL)
• relaxin

Question 20

What does hCG do?

Answer 20

maintains CL of pregnancy until end of first trimester

Question 21

What does estrogen (E) do?

Answer 21

stimulates growth of myometrium, strengthening it for parturition

Question 22

What does progesterone (P) do?

Answer 22

suppresses uterine contractions

Question 23

What does human placental lactogen (hPL) do?

Answer 23

affects maternal metabolism to make more glucose and fatty acids available for fetus

Question 24

Which hormones are involved in maturation of mammary glands?

Answer 24

E, P, and hPL

Question 25

What does relaxin do?

Answer 25

softens cervix and loosens pubic symphysis between pelvic bones in preparation for parturition

Question 26

Hormones of Pregnancy: Brief Review

REVIEW LECTURE VIDEO

Answer 26

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Question 27

Maternal-Placental-Fetal Unit

REVIEW LECTURE VIDEO

Answer 27

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