Integrative Physiology: Pregnancy & Birth

Front 1

What are the lifespans (in hours) of the ovum and sperm in the reproductive tract?

Which is more viable?

Back 1

Ovum = 72 hours

Sperm = 120 hours

*Viability of sperm stays more constant than ovum during its respective lifespan in the female reproductive tract.

Front 2

During ovulation, how does the egg pass from the ovary to Fallopian tube?

Back 2

Chemotaxis: 'guiding' of the egg through chemical signals.

Front 3

When is the most optimal time for fertilization?

Back 3

Day 1 of ovulation, when egg is still in the Fallopian tube.

Front 4

What is a fertilized ovum called?

Back 4

A zygote

Front 5

The spherical mass of dividing cells at the 3-4 day mark after fertilization is called?

Back 5

A morula

Front 6

A Blastocyst is formed after how many days?

Back 6

4-5 days

Front 7

The Blastocyst implants into the body of the uterus after how many days?

Back 7

5-9 days

Front 8

What are the 2 major component parts of the Blastocyst?

*Bonus: What do each of these parts eventually become?

Back 8

Trophoblast cells: encapsulate the sphere, and eventually become the placenta.

Inner cell mass: eventually becomes the embryo, then fetus.

Front 9

Proliferation & thickening of the endometrium happens when in the cycle?

Back 9

Follicular Phase, Proliferative Phase

Front 10

The glands secrete a clear fluid into the uterus during which phase?

Back 10

Secretory Phase

Front 11

Implantation of the zygote is possible during which phase?

Back 11

Secretory Phase

Front 12

Which part of the Blastocyst is the first point of contact with the surface of the uterus during implantation?

Back 12

The Trophoblast cells: they 'invade' the endometrium.

Front 13

T/F: Trophoblast cells produce enzymes that digest protein, further facilitating invasion process into the endometrium.

Back 13

True

Front 14

What are Cytotrophoblasts & Syncitiotrophoblast cells?

Back 14

The 2 cell types that Trophoblast cells differentiate into following implantation.

Front 15

Where are the Cytotrophoblast and Syncitiotrophoblast cells geographically located?

Back 15

Cytotrophoblasts: remain close to inner cell mass - very organized.

Syncitiotrophoblasts: continue aggressively invading into the endometrium - more 'spread out'.

Front 16

The point where implantation occurs in the endometrium is called the...

Back 16

Decidua

Front 17

What hormone acts locally to increase vascularization and cause edema?

*Bonus: What is the purpose of edema?

Back 17

Prostaglandins

Edema further facilitates the invasion process

Front 18

T/F: Implantation in humans & primates is eccentric.

Back 18

False: implantation is complete in human & primates.

This is called Interstitial Implantation.

Front 19

T/F: Maternal immunosuppression helps in ensuring the mother does not reject the embryo/fetus?

Back 19

True

Front 20

How long do fetal trophoblasts & stem cells prevail in the mother?

Back 20

Many years

Front 21

We refer to an embryo for the first ______ weeks, after which we refer to the _______.

Back 21

8 weeks, fetus

Front 22

Features such as the head & limbs are discernible by ______ weeks.

Back 22

5 weeks

Front 23

What is the amnion? When does it form?

Back 23

A clear membrane that forms around the fetus at the 5 week mark.

Front 24

What fills the amnion? Give an example of the purpose of this.

Back 24

Amniotic fluid, cushions the fetus from physical movements of the mother.

Front 25

About when does the placenta begin to develop?

Back 25

5 week mark

Front 26

When is the placenta well formed?

Back 26

By 8 weeks

Front 27

When does the fetus take on a more discernibly human shape?

Back 27

By 8 weeks

Front 28

In the absence of the placenta, how does the embryo exchange nutrients & waste material?

Back 28

By diffusion

Front 29

How does the mother's body know it is pregnant?

Back 29

Conceptus produces important factors that signal to the mother that she is pregnant; this prevents further reproductive cycles.

Front 30

At the 6 week mark, the primary exchange interface between the mother and the fetus is...

Back 30

The placenta

Front 31

What does the Discoid Haemomonochorial Placentation mean?

Back 31

Discoid: refers to the disk shape of the placenta.

Hemomonochorial: refers to the single layer of trophoblast cells between the maternal & fetal blood.

Front 32

Do maternal and fetal blood mix? Why or why not?

Back 32

No.

Maternal & fetal blood do not mix because of the single layer of trophoblast cells called the hemomonochorial

Front 33

Is the placenta of maternal or fetal origin, and why?

Back 33

Fetal origin, due to the trophoblast cells having invaded the endometrium.

Front 34

How many Chorionic Villi are there in the placenta?

Back 34

Approximately 200

Front 35

The fetus is attached to the placenta by what physical structure?

Back 35

An umbilical cord

Front 36

Which hormone is responsible for maintaining the Corpus Luteum (CL) in the 1st trimester?

Back 36

hCG (Human Chorionic Gonadotrophin)

Front 37

What are 2 sources of hCG?

Back 37

1. Blastocyst

2. Early placenta

Front 38

What are the 2 sources of estrogen during pregnancy?

Hint: (1 in very early pregnancy, 1 later on)

Back 38

1. Produced initially by CL (Corpus Luteum)

2. Placenta once it is sufficiently developed

Front 39

What are 3 important functions of estrogen?

Back 39

1. Stimulates growth of myometrium (muscle layer of uterus).

2. Breast & mammary gland development

3. Fetal development

Front 40

What are the 2 sources of progesterone?

Back 40

1. Placenta

2. Small amounts from the CL (Corpus Luteum)

Front 41

Why is progesterone important in preserving a pregnancy? (2 reasons)

Back 41

1. Inhibits spontaneous uterine contractions.

2. Inhibits follicular developement so body does not go through the process of fertilizing another ovum.

Front 42

The placenta is a source of 4 hormones; what are they?

Back 42

1. Estrogen

2. Progesterone

3. Human Placental Lactogen (hPL)

4. Relaxin

Front 43

What function does hPL serve? (2 functions)

Back 43

1. Prepares mammary gland for lactation.

2. Reduces maternal utilization of glucose - glucose sparing.

Front 44

The hormone relaxin has 2 main functions; what are they?

Back 44

1. Soften cervix to facilitate delivery.

2. Loosens connective tissue between pelvic bones to facilitate birth.

Front 45

Pregnancy is approximately how many days? This translates to _______ months.

Back 45

280 days, 9 months.

Front 46

___________ is the most predominant form of estrogen with respect to pregnancy:

(a) Estrone

(b) Estrodiol

(c) Estriol

Back 46

(c) Estriol

Front 47

T/F: Estrogen is the hormone that reaches the highest profile during pregnancy?

Back 47

False: It is progesterone

Front 48

When the placenta is discharged from the uterus, which hormones drop off really rapidly?

Back 48

1. Progesterone

2. Estrogen (Estriol)

3. Human Placental Lactagen (hPL)

Front 49

T/F: hCG (Human Chorionic Gonadotrophin) has a similar structure & activity to LH (Lutenizing Hormone)?

Back 49

True

Front 50

What is the main source of progesterone and estrogen for the 1st 6 weeks of pregnancy?

*Bonus: After 6 weeks of pregnancy, what is the main source of both of these hormones?

Back 50

1. Corpus Luteum - 1st 6 weeks

2. Placenta - 6 weeks and onwards

Front 51

T/F: After 6 weeks of pregnancy, human pregnancy can proceed without the ovary?

Back 51

True: the Corpus Luteum (CL) is sustained by the ovary until the 6 week mark.

Front 52

What is the clinical significance of an ovarian malignancy at the 6 week mark of pregnancy?

Hint: Corpus Luteum

Back 52

Since the CL is no longer needed and it was the ovary that supported the development & maintenance of the CL, if there is an ovarian malignancy discovered at this point (6+ weeks) you can remove the ovaries with minimal effect on the pregnancy.

Front 53

Why is hCG used as an accurate pregnancy test?

Back 53

It is secreted in the maternal urine.

Front 54

What hormone decreases maternal glucose utilization?

*Bonus: When does it rapidly increase?

Back 54

1. Human Placental Lactagen (hPL)

2. Increases dramatically during late gestation.

Front 55

Is hPL a steroid-type, or peptide-like hormone?

What is significant about this?

Back 55

1. It is peptide-like.

2. Produced by the placenta, and secreted in maternal circulation but doesn't easily cross the placenta to the fetus so it maintains a hPL gradient.

Front 56

What hormone increases maternal lipolysis?

Back 56

hPL - mother can use free fatty acids as an energy source, instead of glucose.

Front 57

T/F: hPL increases retention of Na+, K+, Ca2+?

Back 57

True

Front 58

What 2 things does steroid production in human pregnancy require?

What is this unit called?

Back 58

1. Placenta

2. The fetus

3. The Fetoplacental Unit

Front 59

After 6 weeks, the placenta contains all the enzymes that allow for conversion of _____________ --> progesterone.

Back 59

Cholesterol

Front 60

The placenta does NOT contain the enzymes to convert progesterone --> ______________.

Back 60

Androgens

Front 61

Conversion of progesterone --> androgens is a critical step in the production of __________.

Back 61

Estrogens

Front 62

Why does progesterone pass easily across the membrane from maternal circulation to fetal circulation?

Back 62

Because it is a steroid hormone (lipophillic, hydrophobic)

Front 63

Progesterone passes from the maternal circulation to the fetal circulation where it is converted to ____________ in the fetal _________.

Back 63

Androgens, adrenal.

Front 64

T/F: The primary androgen produced by the fetus is testosterone?

Back 64

False: It is DHEA

Front 65

What is the significance of the 'S' in DHEAS?

Back 65

The S represents 'sulfoconjugation' whereby sulfoconjugation decreases/dampens androgenic potency of DHEA in fetal circulation.

Prevents masculinization effects during critical window of fetal development.

Front 66

Where is DHEAS converted into 16a-DHEAS?

Back 66

In the fetal liver.

Front 67

What estrogen does 16a-DHEAS yield?

Back 67

Estriol, in the placenta

Front 68

If DHEAS does *not* pass to the fetal liver, what estrogens are produced, and where?

Back 68

Estradiol & Estrone

In the placenta

Front 69

The production of ___________ requires action of the fetal liver.

Back 69

Estriol

Front 70

For delivery to occur, the cervix which is usually _________ must _________.

Back 70

Closed/tightly closed, dilate

Front 71

Cervical ripening requires these 2 hormones.

Back 71

Prostaglandin, Relaxin

Front 72

The 2 distinct processes of parturition are:

Back 72

1. The Trigger

2. Process of Fetal Expulsion

Front 73

What are some potential mechanisms for pre-term labour?

Do we know what the *ultimate* trigger is; which is it?

Back 73

1. Increased expression in oxytocin receptors in the uterus.

2. Dramatic increase in fetal cortisol concentrations.

3. Dramatic increase in Placental CRH. High levels of CRH secreted by placenta pass into fetal circulation which activates fetal pituitary to produce ACTH; leads to increased fetal cortisol.

4. Increased prostaglandins

NO. We do not know if it is a single trigger or integrated trigger.

Front 74

About what % of pregnancies in the US are pre-term?

How costly is this?

Back 74

1. 7-10%

2. US $8 billion/year

Front 75

T/F: Administering oxytocin receptor antagonist can stop the birth process.

Back 75

False: it can only slow it down

Front 76

What reflex is responsible for the massive increase in oxytocin secretion?

Back 76

The Neuroendocrine Reflex. Massive increase in oxytocin secretion from Maternal pituitary passes to uterus --> causes further uterine contractions.

Front 77

Almost _____% of births are induced today.

Back 77

20%

Front 78

Inductions involves 2 hormones in sequence.

1. What are the hormones?

2. How and where are they administered?

Back 78

Question 1

1. Prostaglandins

2. Oxytocin

Question 2

1. Directly to cervix to help in cervical ripening & softening.

2. Through IV drip (intravenously) to induce uterine contractions.

Front 79

Maternal, oxygenated & nutrient-rich blood flows into the ______ through the maternal ______.

Back 79

sinus, artery

Front 80

Maternal, de-oxygenated blood carrying waste products ________ the sinus through the maternal _________.

Back 80

leaves, venules

Front 81

Blood carrying CO2 & waste products is pumped _____ of the fetal ______ to the placenta via the fetal umbilical ________.

Back 81

out, heart, artery

Front 82

Re-oxygenated & nutrient-rich blood passes back to the ______ via the __________ umbilical ______.

Back 82

fetus, fetal, vein

Front 83

Within the human breast, there are many _____-producing alveoli.

Back 83

milk

Front 84

The cells that secrete milk are called the _____ __________cells and the contraction of the __________ cells causes the milk to move from the central region of the alveoli to the _____ duct.

Back 84

epithelial milk secreting cells, myoepithelial cells, milk.

Front 85

Why is no milk produced during pregnancy?

Hint: Hormones that inhibit prolactin

Back 85

High levels estrogen & progesterone inhibit action of prolactin on the milk-secreting cells.

Front 86

__________ can act to initiate milk production once the hormonal influence of the placenta has been removed.

Back 86

Prolactin

Front 87

Which hormone acts on the myoepithelial cells to cause the muscular contraction which propels milk forward?

Back 87

Oxytocin

Front 88

The process of milk production is known as...

Back 88

Galactotopoeisis

Front 89

What 2 things can galactopoesis be initiated by?

Back 89

1. The baby suckling.

2. The baby crying.

Front 90

Mechanoreceptors in the nipple activate the ________________ response reflex.

Back 90

neuroendocrine

Front 91

When a baby cries, it activates lactation via what mechanism?

Back 91

Higher brain centres

Front 92

What hormone usually inhibits prolactin secretion in the pituitary?

Back 92

Dopamine

Front 93

T/F: Pregnancy is a requirement for lactation.

Back 93

False

Front 94

The milk ejection reflex is controlled by the secretion of what hormone in the maternal pituitary?

Back 94

Oxytocin

Front 95

Why is the milk ejection reflex considered a conditioned response?

Back 95

The baby's smell or cry can activate the process of the milk ejection reflex.

Front 96

Why is it important to provide a relaxing, stress-free environment for new nursing mothers?

Back 96

Milk ejection reflex is *potently* inhibited by psychological stress.

Front 97

Individuals with _______ birth weights were at much higher/lower risk for developing cardiovascular diseases later in life, as observed in David Barker's work in the 1980s.

Back 97

low, higher

Front 98

T/F: The highest birth weight (9.5 lbs+) represented the highest risk group for development of cardiovascular disease?

Back 98

False: It was the low weight births between 5.5 - 6.0 lbs at birth.

Front 99

T/F: Male babies were generally proportionately *more* at risk at developing cardiovascular diseases than female babies?

Back 99

True

Front 100

Metabolic syndrome involves these 3 features:

Back 100

1. Hypertension

2. Insulin insensitivity/diabetes

3. Obesity

Front 101

T/F: The lower the birth weight, the higher the risk of developing metabolic syndrome?

Back 101

True

Front 102

David Phillips took the same longitudinal data set from David Barker's studies and plotted birthweight against plasma cortisol levels.

What did he discover with respect to low birth weights?

Back 102

The lower the birth weight, the higher the plasma concentration of circulating cortisol.

Front 103

Increased cortisol levels is associated with ________ blood pressure.

Back 103

higher or increased

Front 104

The result of these longitudinal studies on birth weights and disease outcome in adulthood, suggest that regulating ________ secretion by the ________ glands may be the link between low birth weight & adult disease.

Back 104

cortisol, adrenal