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Reproductive System > Physiology of Pregnancy, Parturition and Lactation > Flashcards

Physiology of Pregnancy, Parturition and Lactation Flashcards

1
Q

What is the name of the membrane that is broken upon labor?

A

Amniochorionic Membrane

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2
Q

Describe the three major structures of the Mature Placenta.

A
  1. Chorionic Villi: Functional UNIT of the placenta, its extensive branching will increase the surface area for EXCHANGE between mother and fetus
  2. Intervillous Space: Spiral Arteries from the mother are going to empty into here
  3. Decidua Basalis
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3
Q

What are some of the functions that the Placenta will provide for the baby?

A

Fetal “gut”: Supplying Nutrients

Fetal “lung”: Exchanging O2 and CO2

Fetal “kidney”: Regulates fluid volumes and disposing of waste metabolites

Endocrine Gland: Synthesizes steroid and proteins (Syncytiotrophoblasts)

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4
Q

Which structures act as the functional capillaries between the mother and fetus?

A

Intervillous Space! (There are NO anastamoses between mom and baby)

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5
Q

What is a factor that will regulate maternal blood flow?

A

Uterine Contractions: ATTENUATE arterial inflow and completely INTERRUPT venous drainage

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6
Q

What are two important functions of the amniotic fluid?

A
  1. Serves as a mechanical buffer protectinf the fetus from the external environment
  2. Fetus excretes waste products through it
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7
Q

Describe how gases move across the placenta.

A

Diffusion of O2 from the maternal blood into the Chorionic Villi of the fetus causes the PO2 of blood in the Intervillous space to fall

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8
Q

Which has a high affinity for O2, Maternal or Fetal Hb?

A

FETAL!

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9
Q

Which structures are going to use Passive, Simple Diffusion, Facilitated Diffusion, Secondary Active, Primary Active transport, and Receptor-Mediated endocytosis?

A

Passive: Waste Products Urea and Creatinine

Simple Diffusion: Lipid-Soluble Steroid Hormones

Facilitated Diffusion: Glucose

Secondary Active: Amino Acids

Primary Active: Vitamins and Minerals

Receptor-Mediated Endocytosis: LDL, Transferrin, insulin (hormones), IgG (Antibodies)

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10
Q

List the four hormones that are made by the placenta. Describe their secretion patterns in relation to weeks of gestation and their function.

A
  1. hCG: Peak is going to be around 10 weeks and then starts to decrease
  2. Progesterone: Starts being formed around 8 weeks gestation and will increase until birth. Important for maintaining the MYOMETRIUM
  3. Human Placental Lactogen Hormone: Developed from the Syncytiotrophoblast and is important for Diabetogenic State of Pregnancy
  4. Estriol: Predominant form during pregancy
    Estradiol: Predominant form during “baby-making” years
    Estrone: Predominant form during menopause
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11
Q

Does hCG bind with low or high affinity to LH receptors?

A

HIGH AFFINITY

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12
Q

What is responsible for the nausea of morning sickness?

A

Rapid increase in hCG!

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13
Q

What is the function of Human Placental Lactogen?

A
  • ANTAGONISTIC action to INSULIN, contributing to the diabetogenicity of pregnancy (inhibits Maternal uptake of glucose so the Baby can have more glucose
  • Helps the mother to shift to the use of free fatty acids for energy
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14
Q

Which hormone can help you to determine the well-being of the fetus?

A

Estriol

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15
Q

List the functions of Estrogen in pregnancy.

A
  • Increase uteroplacental blood flow
  • Enhance LDL expression in Syncytiotrophoblasts
  • Induce Prostaglandins and Oxytocin Receptors which are involved in parturition
  • Increase growth and development of MAMMARY glands
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16
Q

Where does the Placenta (Syncytiotrophoblast) get the Cholesterol that is used to make Progesterone?

A

LDL from Maternal Liver

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17
Q

When does Implantation usually occur in the Menstruation cycle?

A

Day 21

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18
Q

List three functions of Progesterone.

A
  1. Stimulates secretion from Uterine GLANDS, which provide nutrients to the embryo (HISTOTROPHIC nutrition)
  2. Inhibits MYOMETRIAL contraction and prevents the release of paracrine factors that leads to MENSTRUATION
  3. Induces “Window of Receptivity”: When the Blastocyst needs to be implanted into the Endometrium
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19
Q

What is the type of nutrition that occurs in the first trimester of Pregnancy? What does it change to after the 1st trimester?

A

1st Trimester: HISTOTROPHIC nutrition

Rest: HEMOTROPHIC nutrition

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20
Q

Which Enzyme in the Placenta is responsible for converting Pregnenlone to Progesterone?

A

3B-Hydroxysteroid Dehydrogenase

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21
Q

Which enzyme is responsible for removing the Sulfate group from DHEA-S so that the placenta can use DHEA?

A

Sulfatase (From the Placenta)

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22
Q

Where is Aromatase located?

A

PLACENTA!

23
Q

Explain how Estriol is created.

A
  • Fetus will convert DHEA-S to 16a-OH DHEA-S (16a-Hydroxylase) in the liver
  • Sulfatase (in placenta) will take off the Sulfate group from 16a-OH DHEA-S
  • 16a-OH DHEA is converted to ESTRIOL (Aromatase) in the placenta and then sent over to the MOM
24
Q

How is DHEA-S made?

A

17a-Hydroxylase and 17,20-Desmolase activity is in the ADRENAL glands of the FETUS!

25
Q

How does the Maternal-Placental-Fetal unit overcome the placental limitations?

A
  1. Mother supplies most of the cholesterol to make Progesterone via LDL particles
  2. Fetal Adrenal Glands (17a-Hydroxylase and 17, 20 Desmolase) and Liver (16a-Hydroxylase) are going to supply the three enzymes the placenta is lacking
26
Q

Describe the 3B-HSD BLOCK in the Fetus.

A
  • Fetus cannot make Estrogens on its own because it lacks the enzymes 3B-HSD and AROMATASE
  • If the fetus were able to make its own estrogens, it would expose itself to dangerously HIGH levels of hormones
27
Q

What is the purpose of Sulfinating Products in the Fetus?

A

Decreases the activity of certain substrates so they do not overproduce androgens (estrogen)

28
Q

How does the mother increase the blood volume during pregnancy? When does the increase start? What is responsible for the increase in blood volume?

A

Mostly by an increase in blood plasma

Starts in the 1st Trimester and continues to increase throughout the pregnancy

Renin-Angiotensin-Aldosterone Axis

29
Q

Describe the changes in Mean Arterial Pressure throughout pregnancy. What hormones are responsible for this change?

A

Mean Arterial Pressure (MAP) will decrease during mid-pregnancy and then rises during the 3rd trimester

Decrease in peripheral resistance due to the vasodilating effects of Progesterone and Estradiol.

30
Q

Which hormones are going to be responsible to keep the uterus quiescent throughout pregnancy?

A
  1. Progesterone

2. Relaxin

31
Q

When does the birth process typically occur? (in weeks)

A

38 weeks after fertilization

40 weeks after last menstrual period

32
Q

Which two hormones are responsible for maintaining labor?

A
  1. Oxytocin

2. Prostaglandins

33
Q

When does the active labor stage (2nd) of pregnancy occur?

A

@ 10cm Dilation of the Cervix

34
Q

What is the final (Stage 3) stage of labor?

A

Delivery of the PLACENTA

35
Q

What is the narrowest part of the Mother’s Pelvis?

A

Ischial Spine

36
Q

Describe the Fetal Stations in relation to the Ischial Spine with Positive and Negative numbers.

A

Ischial Spine = 0

ABOVE Spine = Negative

BELOW Spine = Positive

37
Q

Describe the HPA axis that is involved in Parturition.

A
  • Placenta produces CRH
  • CRH stimulates fetal production of ACTH and fetal adrenals produce CORTISOL and FETOPLACENTAL ESTROGEN
  • Cortisol provides POSITIVE feedback to increase placental CRH production
  • CRH promotes contractions by SENSITIZING uterus to PROSTAGLANDINS and OXYTOCIN
  • Estrogens also STIMULATE contractions
38
Q

Describe the effects of Estrogen in initiating Parturition.

A
  • INCREASE the degree of Uterine Contractility

- Stimulates the synthesis of OXYTOCIN receptors

39
Q

Describe the effects of Prostaglandins in initiating Parturition.

A
  • Believed to INITIATE LABOR
  • Uterine Stretch is going to stimulate prostaglandin production
  • PGF 2a and PGE 2 are the main prostaglandins that are involved in INCREASING uterine motility (can be used to INDUCE labor)
40
Q

What are the two stimuli for the release of Oxytocin? When is the uterus sensitive to Oxytocin?

A
  1. Stretch of the Cervix: Release of Oxytocin
  2. Estrogen: Increases Oxytocin Receptors!

Uterus is sensitive to Oxytocin ONLY at the END of pregnancy

41
Q

What is the Ferguson reflex?

A
  • Stretch of the cervix will STIMULATE the release of Oxytocin
  • Oxytocin will STIMULATE powerful uterine contractions that will SUSTAIN Labor
42
Q

What is the function of Oxytocin during the 3rd stage of Labor?

A

Causes Uterus to CONTRACT after the fetus is expelled and that will LIMIT blood flow / blood loss

43
Q

Describe the function of Relaxin.

A
  • Keeps uterus quiescent during pregnancy

- Dilates the cervix during Labor

44
Q

Describe the effect of the FETAL hormones on the Uterus.

A

Fetal Pituitary: Increase OXYTOCIN

Fetal Adrenals: Increase CORTISOL

Fetal Placental Membranes: Increase levels of PROGESTERONE

45
Q

Describe the mechanical changes during parturition.

A

Stretching the smooth muscle organs will INCREASE the amount of Uterine Contractions (POSITIVE FEEDBACK)

46
Q

Differentiate between Braxton Hicks and Labor Contractions.

A

Braxton Hicks: Occur during most of pregnancy; Uterus undergoes periodic episodes of WEAK and SLOW rhythmic contractions

LABOR: Contractions start stretching the CERVIX and later force the baby through the birth canal

47
Q

List the two Positive Feedback Mechanisms that are involved in Labor.

A
  1. Uterine Contractions stimulate prostaglandin release, which will INTENSIFY the uterine contractions
  2. Uterine Activity stretched the Cervix, which will stimulate the Release of OXYTOCIN to cause further dilation of the Cervix (Ferguson Reflex)
48
Q

What is considered a Pre-Term baby?

A

Labor BEFORE 37th Week

49
Q

Describe the pathophysiology and clinical presentation of preeclampsia.

A
  • HIGH blood pressure, Increase Excretion of PROTEINS in the urine (damage to another organ), and GENERALIZED edema
  • No definitive cause but it may be involved with Disease of the PLACENTA
  • DEFICIENT TROPHOBLAST invasion of the SPIRAL arteries which can lead to placental ISCHEMIA
  • Decrease in NO and Prostaglandins
  • AT1 AutoAntibodies is going to enter the vasculature and INCREASE the Total Peripheral Resistance
50
Q

What important lactation hormone ENHANCES contraception and INHIBITS ovulation?

A

Prolactin

51
Q

Describe the five major pathways of secretion of milk components by alveolar cells.

A
  1. Secretory Pathway: Milk Proteins Lactalbumin and Casein are synthesized in the ER and are sorted to the Golgi; LACTOSE SYNTHETASE in the lumen of the GOLGI will make Lactose
  2. Transcellular Endocytosis and Exocytosis: Maternal Immunoglobulins (Primarily IgA) are taken up by endocytosis through the Basolateral Membrane
  3. Lipid Pathway: Secretes Fatty acids from the lipid droplets
  4. Transcellular Salt and Water Transport: Water will follow an osmotic gradient generated primarily by LACTOSE
  5. Paracellular Pathway: Salt, Water and LEUKOCYTES can move through tight junctions between CELLS
52
Q

Explain the effects of suckling on hormone release during lactation.

A
  • Suckling will travel to the hypothalamus and inhibit the release of DOPAMINE and GnRH (Decrease levels of FSH and LH which will inhibit the Ovarian Cycle)
  • STIMULATES release of Oxytocin
53
Q

What is going to inhibit the action of Prolactin during pregnancy?

A

HIGH estrogen and Progesterone Levels

54
Q

What is Colostrum?

A

Thin, yellowish milk-like substance that is secreted the first few days after parturition, contains a high concentration of IMMUNOGLOBULINS

Reproductive System (20 decks)

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