Part 2: Physiology Of Pregnancy, Parturition, And Lactation Flashcards
When does human birth occur?
40 weeks of gestation
What is involved in parturition?
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
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?
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
What are the characteristics of the stages of parturition?
0:
1:
2:
3:
Uterine tranquility and refractoriness to contraction
Uterine awakening, initiation of parturition extending to complete cervical dilation: increase number of gap junctions
Stages of parturition:
_____ is relaxed, quiescen, relatively insensitive to hormones that stimulate ____
Uterus; contractions
When is uterine excitability increased?
Towards the end of pregnancy
Prior to labor, _____ transforms to a more contractile state
What stage is this?
What is produced?
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
What state is active labor induced?
What three major factors induce contractions?
Stage 2
Increased levels of prostaglandins, increased myometrium cell interconnectivity, increased myometrium responsiveness to PG and oxytocin
Contractions forces ____ again the cervix. It becomes more compliant as the _____ remodels.
____ dilates enough to allow fetus through the birth canal.
Fetal head; extracellular matrix
Cervix
Reciprocal changes in uterin progesterone and estrogen receptors
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What is the fx of prostaglandins?
Synthesis of prostaglandins are stimulated by ______, _____, and _____.
Increase in
Estrogen in fetal membranes
Oxytocin in uterine cells
Uterine stretch
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Uterus is insensitive to oxytocin until ____ weeks. ____ increases oxytocin receptors. These receptors increase 80x higher than baseline by ___ weeks. Increase ____x by early labor.
20
Estrogen
36
200
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.
Oxytocin
PGF 2alpha
Cervix; Ferguson
What is relaxin>
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What are the mechanical changes of the uterus during labor>
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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.
CRH
Later pregnancy and labor
Promotes myometrial contractions -> sensitizing uterus to prostaglandins and oxytocin
Yes; ACTH
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Most of pregnancy uterus undergoes periodic episodes of ____ called ____.
They become strong during ____ of pregnancy into active labor.
What is their fx?
Weak and slow contractions; Braxton hicks contractions
Last hours
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Fetal station
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Dilation and effacement
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Dilation and eff
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Descent and expulsion
Cervix fully dilated
Contractions are stongest at top pushing fetus down
Expulsion of placenta
Uterus contracts refusing area of attachment
Separation of placenta results in bleeding and clotting
What is prolonged labor?
What is the cause?
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
What is obstructed labor or labor dystocia?
What is the causes?
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
What is a breech presentation?
What are the types?
What are the causes?
What are the risks of labor?
Non-vertex presenting part (buttocks)
Complete, footling, frank breech
Large baby, no fluid, birth defects, uterine anomalies
Fetal injury, cord prolapse, entrapment, maternal injury
When the integrity of the myometrial wall is breached, this causes _____.
When can this occur?
What are the risks?
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
What is considered preterm labor?
Early uterine contractions cause what?
Before 37th week
Cervix to open earlier than normal
When does preeclampsia occur?
What is it characterized by?
After week 20 of pregnancy
High BP and signs of damage to another organ system (kidneys)
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.
Preeclampsia
Uterine arteries
Trophoblastic invasion
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 ____.
15-20
Glandular and fibrous and adipose tissue
Alveoli; lactiferous ducts
What are the two types of epithelium in mammary glands?
Alveolar epithelium
Myoepithelial cells
The breast consists of a serious of _____ the empty into ductules.
Secretory lobues
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
Lactiferous ducts
Puberty
Estrogens
As menstrual cycle is established, mammary tissue is exposed to ____ and ____ inducing additional _____ growth.
Cyclic changes to breast occurs such as what?
Estrogen and progesterone; ductal-lobular-alveolar growth
Increase in breast volume, breast tenderness, secretory activity, involution
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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
Duct and lobule proliferation complete; differentiation of alveolar cells
Estrogen and progesterone
Colostrum
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.
Steroid
3-4 weeks
Neuroendocrine reflex
Prolactin
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What is the fx of oxytocin in milk lactation?
Enhances milk ejection by stimulating the contraction of the network of myoepithelial cells surrounding the alveoli and ducts of the breast (galactokinetic effect)
What are the five pathways that alveolar epithelial cells secrete milk components?
Secretory pathway
Trans cellular endocytosis and exocytosis
Lipid pathway
Transcellular salt and water transport
Paracellular pathway
Describe the secretory pathway of milk production
Lactalbumin and casein synthesized in the ER
Ca and Pi added to lumen of golgi
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What are the four effects of sucking on hormone release?
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
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
Accumulates
Epithelial structures; alveolar; capillaries; alveolar hypoxia
Phagocytosed
Smaller
Ductal
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