Part 2: Physiology Of Pregnancy, Parturition, And Lactation

Question 1

When does human birth occur?

Answer 1

40 weeks of gestation

Question 2

What is involved in parturition?

Answer 2

Transformation of the myometrium from quiescent to contractile

Remodeling of the uterine cervix; softens and dilates

Rupture of fetal membranes

Expulsion of uterine contents

Return of the uterus to its prepregnant state

Question 3

Labor is a series of regular, rhythmic, and forceful contractions that develop to facilitate _____.

How long do contractions last? What is the result?

What sustains labor?

Answer 3

Thinning and dilation of the cervix

Several hours, day, of longer; result is expulsions of the fetus, placenta, and membranes

Series of positive feedback mechanisms

Question 4

What are the characteristics of the stages of parturition?

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Answer 4

Uterine tranquility and refractoriness to contraction

Uterine awakening, initiation of parturition extending to complete cervical dilation: increase number of gap junctions

Question 5

Stages of parturition:

_____ is relaxed, quiescen, relatively insensitive to hormones that stimulate ____

Answer 5

Uterus; contractions

Question 6

When is uterine excitability increased?

Answer 6

Towards the end of pregnancy

Question 7

Prior to labor, _____ transforms to a more contractile state

What stage is this?

What is produced?

Answer 7

Myometrium

Stage 1: transformation/activation

Contraction-associated hormones and proteins:

Prostaglandins F2alpha receptors
Oxytocin receptors
Enzymes involved in prostaglandin synthesis
Enzymes that break down collagen matrix in cervix
Gap junctions complexes

Question 8

What state is active labor induced?

What three major factors induce contractions?

Answer 8

Stage 2

Increased levels of prostaglandins, increased myometrium cell interconnectivity, increased myometrium responsiveness to PG and oxytocin

Question 9

Contractions forces ____ again the cervix. It becomes more compliant as the _____ remodels.

____ dilates enough to allow fetus through the birth canal.

Answer 9

Fetal head; extracellular matrix

Cervix

Question 10

Reciprocal changes in uterin progesterone and estrogen receptors

Answer 10

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Question 11

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Answer 11

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Question 12

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Answer 12

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Question 13

What is the fx of prostaglandins?

Synthesis of prostaglandins are stimulated by ______, _____, and _____.

Answer 13

Increase in

Estrogen in fetal membranes

Oxytocin in uterine cells

Uterine stretch

Question 14

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Answer 14

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Question 15

Uterus is insensitive to oxytocin until ____ weeks. ____ increases oxytocin receptors. These receptors increase 80x higher than baseline by ___ weeks. Increase ____x by early labor.

Answer 15

20

Estrogen

36

200

Question 16

During active labor, _____ stimulates uterine contractions that sustain labor.

Stimulate ____ production in decidual cells.

This hormone is the primary stimulus for release of distention of the ____ known as the ____ reflex.

Answer 16

Oxytocin

PGF 2alpha

Cervix; Ferguson

Question 17

What is relaxin>

Answer 17

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Question 18

What are the mechanical changes of the uterus during labor>

Answer 18

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Question 19

What does the placenta produce during labor?

When do maternal levels rise of this hormone?

What is the fx?

Does it accumulate in fetal circulation? It stimulates fetal ____ secretion.

Answer 19

CRH

Later pregnancy and labor

Promotes myometrial contractions -> sensitizing uterus to prostaglandins and oxytocin

Yes; ACTH

Question 20

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Answer 20

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Question 21

Most of pregnancy uterus undergoes periodic episodes of ____ called ____.

They become strong during ____ of pregnancy into active labor.

What is their fx?

Answer 21

Weak and slow contractions; Braxton hicks contractions

Last hours

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Question 22

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Answer 22

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Question 23

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Answer 23

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Question 24

Fetal station

Answer 24

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Question 25

Dilation and effacement

Answer 25

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Question 26

Dilation and eff

Answer 26

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Question 27

Descent and expulsion

Answer 27

Cervix fully dilated Contractions are stongest at top pushing fetus down

Question 28

Expulsion of placenta

Answer 28

Uterus contracts refusing area of attachment Separation of placenta results in bleeding and clotting

Question 29

What is prolonged labor? What is the cause?

Answer 29

Labor lasting more than 18-24 hours Poor uterine contractions, baby’s position of size being abnormal or issues with the pelvis or birth canal

Question 30

What is obstructed labor or labor dystocia? What is the causes?

Answer 30

Uterus is contracting normally, but the baby does not exit the pelvis during childbirth due to being physically blocked Breech, macrosomia, occipital posterior, malpresentation, compound presentation, congenital abnormalities

Question 31

What is a breech presentation? What are the types? What are the causes? What are the risks of labor?

Answer 31

Non-vertex presenting part (buttocks) Complete, footling, frank breech Large baby, no fluid, birth defects, uterine anomalies Fetal injury, cord prolapse, entrapment, maternal injury

Question 32

When the integrity of the myometrial wall is breached, this causes _____. When can this occur? What are the risks?

Answer 32

Ruptured uterus Active labor, late pregnancy Uterine scar, Abdominal pain, vaginal bleeding, deterioration of fetal HR (sign), loss of fetal station on manual vagnial exam

Question 33

What is considered preterm labor? Early uterine contractions cause what?

Answer 33

Before 37th week Cervix to open earlier than normal

Question 34

When does preeclampsia occur? What is it characterized by?

Answer 34

After week 20 of pregnancy High BP and signs of damage to another organ system (kidneys)

Question 35

Disease of the placenta might be involved in ____. Associated with limited blood supply to ____ causing ischemia and endothelial damage with release of cytokines. The placenta is characterized by ____ invasion.

Answer 35

Preeclampsia Uterine arteries Trophoblastic invasion

Question 36

How many lobes are in mammary glands? What type of tissue do they consist of? Each lobe is made of lobules of ____, blood vessels, and ____.

Answer 36

15-20 Glandular and fibrous and adipose tissue Alveoli; lactiferous ducts

Question 37

What are the two types of epithelium in mammary glands?

Answer 37

Alveolar epithelium Myoepithelial cells

Question 38

The breast consists of a serious of _____ the empty into ductules.

Answer 38

Secretory lobues

Question 39

At birth, mammary gland almost entirely ______ with few alveoli. The breast remains in this state until ____. Under the actions of ____, lactiferous ducts sprout and branch

Answer 39

Lactiferous ducts Puberty Estrogens

Question 40

As menstrual cycle is established, mammary tissue is exposed to ____ and ____ inducing additional _____ growth. Cyclic changes to breast occurs such as what?

Answer 40

Estrogen and progesterone; ductal-lobular-alveolar growth Increase in breast volume, breast tenderness, secretory activity, involution

Question 41

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Answer 41

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Question 42

What is complete by mid pregnancy in the mammary glands? Inhibition of lactogenesis by ____ and ____ render mammary cells unresponsive to prolactin. Small amounts of ___ are produced late pregnancy containing high concentration of immunoglobulins

Answer 42

Duct and lobule proliferation complete; differentiation of alveolar cells Estrogen and progesterone Colostrum

Question 43

Following parturition there is a drop in ____ hormone levels. In the absence of sucking, milk secretion will last up to ____ weeks. Suckling stimulates prolactin secretion via a _____ reflex.

Answer 43

Steroid 3-4 weeks Neuroendocrine reflex

Question 44

Prolactin

Answer 44

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Question 45

What is the fx of oxytocin in milk lactation?

Answer 45

Enhances milk ejection by stimulating the contraction of the network of myoepithelial cells surrounding the alveoli and ducts of the breast (galactokinetic effect)

Question 46

What are the five pathways that alveolar epithelial cells secrete milk components?

Answer 46

Secretory pathway Trans cellular endocytosis and exocytosis Lipid pathway Transcellular salt and water transport Paracellular pathway

Question 47

Describe the secretory pathway of milk production

Answer 47

Lactalbumin and casein synthesized in the ER Ca and Pi added to lumen of golgi

Question 48

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Answer 48

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Question 49

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Answer 49

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Question 50

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Answer 50

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Question 51

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Answer 51

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Question 52

What are the four effects of sucking on hormone release?

Answer 52

Sucking stimuli (or sight of sound of child) Dopamine release is inhibited Spinal cord neurons stimulate production and release of oxytocin from posterior pituitary Spinal cord neurons inhibit the arcuate and preoptic area of the hypothalamus causing a fall in GnRH production

Question 53

When the sucking discontinues, the milk ____. There is distention and mechanical atrophy of ____, rupture of ____ walls, compression of ____ resulting in _____ _____. Cell and glandular debris are ____. Lobular-acinar structures become ____. ____ system predominates. Full involution can take ____ months

Answer 53

Accumulates Epithelial structures; alveolar; capillaries; alveolar hypoxia Phagocytosed Smaller Ductal 3