Physiology of Pregnancy

Question 1

T/F the fetus is susceptible to teratogens in the first 1-2 weeks of pregnancy

Answer 1

False; the first ‘2 weeks of pregnancy’ are days 1-14 (ovulation) and actually before conception; during days 14-28 (4 weeks pregnant) teratogens are not thought to have effects because the organ systems don’t start developing until 4 weeks

Question 2

Early pregnancy is considered to be

Answer 2

weeks 3-4, ie after conception (4 weeks from LMP)

Question 3

Embryonic phase is from week

Answer 3

3-8 (5-10 from LMP)

Question 4

Fetal phase is from week

Answer 4

9-38 (term; 11-40 from LMP)

Question 5

Congenital malformations to organ systems are programmed during what phase of development?

Answer 5

Embryonic phase - weeks 3-8 from conception

Question 6

The fetus is considered to be fully functioning at the end of week

Answer 6

8 (10 since LMP)

Question 7

The foetal period is characterized by

Answer 7

exponential growth and maturation of the organ systems

Question 8

Issues that face growth and development during the fetal period result in

Answer 8

functional deficits in the organ systems; can be some minor morphological abnormalities

Question 9

Human chorionic gonadotropin is produced by

Answer 9

the trophoblast (becomes placenta)

Question 10

The membranes surrounding the fetus are

Answer 10

amnion (inner) and chorion (outer)

Question 11

The role of the fetal membranes is

Answer 11

protect fetus and allow fluid transfer (but mainly goes through umbilical cord)

Question 12

The umbilical vein carries __________ blood and the umbilical arteries (2) carry ________ blood

Answer 12

vein carries the oxygenated blood; 2 arteries carry deoxygenated blood (and waste products)

Question 13

The placenta is formed from

Answer 13

trophoblast cells that invade the endometrium

Question 14

What are blood lakes within the placenta?

Answer 14

invasion of trophoblast cells into the endometrium breaks down uterine blood vessels and arterioles forming lakes; chorionic vili contain embryonic blood vessels (foetal capillaries) extending into the lakes

Question 15

What is the purpose of formation of blood lakes?

Answer 15

These regions are safe from vasoactive/vasoconstrictive agents affecting the mother (eg stress, exercise, increased BP) tf the fetal blood supply is not affected by them (exception is pre-eclampsia)

Question 16

Amniotic fluid is composed of

Answer 16

urine, liquid from lungs

Question 17

T/F the gut is inactive during development

Answer 17

False; it is fully functioning though nutrition comes via teh umbilical vein; the foetus swallows amniotic fluid which helps with development

Question 18

T/F the kidneys are functional during development

Answer 18

True; they are producing urine that goes into the amniotic sac; waste products still exit via umbilical arteries

Question 19

Amniotic fluid functions

Answer 19

as a buffer; allows foetal movements and growth; development of GI

Question 20

Oligohydramnios

Answer 20

low amniotic fluid volume; can be detrimental to foetal growth, lung growth, and movements

Question 21

Placental function surmises which organ systems?

Answer 21

Lungs, kidneys, GIT

Question 22

T/F exercise is dangerous in pregnancy

Answer 22

False; as long as uteroplacental blood flow is regulated and maintained and blood flow is not shunted excessively to muscles

Question 23

Which hormones are produced by the placenta?

Answer 23

hCG, human placental lactogen (hPL), estrogen and progesterone

Question 24

hCG from the placenta functions to

Answer 24

rescue the corpus luteum so it can take over for LH and FSH which have declined

Question 25

human placental lactogen (hPL) from the placenta functions

Answer 25

in breast development and maternal metabolic effects

Question 26

Estrogen and progesterone from the placenta function

Answer 26

essentially for almost all of the pregnancy adaptations and maintenance; major role in breast development

Question 27

Other hormones produced by the placenta include

Answer 27

growth factors, CRH, ACTH

Question 28

Monozygotic twins arise from

Answer 28

one zygote that splits and forms 2 embryos; tf they are genetically identical and the same sex because they come from a single fertilized ovum

Question 29

Dizygotic (fraternal) twins arise from

Answer 29

2 oocytes ovulated and fertilized by 2 separate sperm; tf they are non genetically identical and can be the same or different sex

Question 30

Development and maturation of organ systems through the foetal period is largely driven by

Answer 30

cortisol

Question 31

What must occur prior to labour?

Answer 31

Maturation of the fetal organs and softening of the cervix

Question 32

What must occur during labour?

Answer 32

dilation of cervix (1ocm); rhythmic uterine contractions of the myometrium (outer muscle layer); once initiated maintained by positive feedback - eg oxytocin

Question 33

Parturition is triggered by

Answer 33

CRH, ACTH cascade, hormones from placenta and fetus, cervical stretch as the baby drops lower in the uterus, oxytocin from the posterior pituitary (uterine contraction and lactation), prostaglandins from the uterine wall stimulate contractions

Question 34

What is the role of cervical stretch in parturition?

Answer 34

As the fetus drops lower in the uterus, the cervix stretches, upregulating oxytocin release from the posterior pituitary and triggering uterine contraction that furthers cervical stretch

Question 35

What is the role of oxytocin in parturition?

Answer 35

Triggers uterine contractions and prostaglandin release from the uterine wall in response to stretch of the cervix; contraction to deliver the placenta

Question 36

What is the role of prostaglandins in parturition?

Answer 36

Stimulated release from uterine wall by oxytocin, facilitate uterine contraction

Question 37

During pregnancy, ___________ stimulate development of mammary glands

Answer 37

estrogen, GH, cortisol

Question 38

Late in pregnancy, ________ stimulates conversion of mammary ducts to _____________

Answer 38

progesterone; secretory epithelia capable of producing milk

Question 39

Before birth, lactation

Answer 39

is suppressed by prolactin-inhibiting hormone (PIH); milk production is inhibited by high estrogen and progesterone

Question 40

After birth, lactation

Answer 40

is stimulated by high levels of prolactin and low levels of estrogen

Question 41

What is the benefit of breast milk?

Answer 41

It contains all the nutrients and immunity needed specifically by the infant to survive

Question 42

Suckling inhibits

Answer 42

PIH

Question 43

Prolactin stimulates

Answer 43

production of milk

Question 44

Oxytocin in lactation stimulates

Answer 44

milk ejection in response to suckling

Question 45

Lactation inhibits ______ which inhibits _________

Answer 45

GnRH - the ovarian cycle and ovulation to prevent another pregnancy - natural birth spacing

Question 46

Suckling stimulates

Answer 46

inhibition of PIH/production of prolactin to stimulate milk production (next feed) and oxytocin for milk ejection (current feed)