Parturition, Lactation, and Neonatal Physiology Flashcards

1
Q

Reciprocal changes between what two hormones are necessary for the onset of labor?

A

Progesterone and estrogen

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2
Q

Progesterone blocks contractions normally. So to give birth, how does this change?

How does estrogen help the labor process?

A

Progesterone receptors on the uterus become desenstized to the hormone

this leads to an increase in estrogen receptor expression

More estrogen binds and allows for an increase in myometrial contraction and cervical dilation

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3
Q

How do prostaglandins help with labor?

A
  • stimulate strong myometrial contractions, cervical effacement, and initiates labor
  • PGF2a potentiates oxytocin induced contractions by increasing gap junction formation
  • synthesis of prostaglanins is stimulated by estrogen in fetus, oxytocin in uterus, uterine stretch
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4
Q

How does oxytocin help with labor?

A
  • UTerus is insensitive to oxytocin until 20wks
  • estrogen receptors increase oxytocin receptors
  • help the myometrium contract and stimulates decidual tissue to produce PGF2a
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5
Q

What is the Ferguson Reflex?

A

during active labor, Oxytocin stimulates uterine contractions

this stimulates PGF2a production

This stimulus for this is cervical distension and these produce further cervical distension/dilation which drives the Ferguson Reflex (positive feeback loop to enhnace labor)

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6
Q

How does Relaxin help with labor?

A
  • cytokine similar to insulin
  • may help keep the uterus quiet during prengnacy and help to soften/dilate cervix toward end of pregnancy
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7
Q

What are the mechanical changes of labor?

A
  • uterine size

stretch of Sm. M increases Ferguson reflex and furthers contractions and stimulates prostaglandin production

  • Cervical remodeling

structural changes resulting in change from fetal support to birth canal

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8
Q

How is labor initiated?

A

Stress.

Placental produces CRH which increases contractions and accumulates in fetus

Fetus makes ACTH which increases fetal cortisol and placental CRH release

Fetal placental estrogen increases to enhance myometrial contractility

so stress causes labor. don’t be stressed.

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9
Q

What are the changes of the uterus and cervix during contractions?`

A

fully dilated cervix is drawn up just below the pelvic inlet

subsequent uterine contractions push fetus downward through the pelvis

first stage is longest, second stage usually less than an hour followed by placental delivery

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10
Q

How is the placenta delivered?

A

uterus contractions reducing area of attachement

sepration of uterus and placenta causes bleeding and clotting

oxytocin helps constrict blood vessels (synthetic given, or nipple stimulation can cause release of oxytocin-nursing)

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11
Q

What is the fetal stimuli for breathing after birth?

A

asphyxiation during birth

sudden drop in temperature/cooling

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12
Q

What are the causes for delayed breathing upon birth?

A

use of general anesthesia during delivery

prolonged labor

head trauma

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13
Q

Describe the baby’s first breath after birth?

A

alveoli are collpased and filled with fluid

more than 25mmHg negative inspr. pressure needed to overcome surface tension and open alveoli

first breath infant capable of -60mmHg and brings in about 40ml of air

deflation of lungs requires strong positive pressure to ovecome viscous resistance of fluid in bronchioles

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14
Q

Blood flow to the placenta shunts blood away from where?

How so?

A

blood is shunted away from the lower trunk in order to reach placenta

Umbilical arteries with lots of branches, capillary network returns deoxygenated blood.

Legs blood flow is connected to IVC

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15
Q

What does the umbilical vein do>

A

returns oxygenated blood to fetus from placenta

blood enters via ductus venosus

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16
Q

What organ is bypassed in the ductus venosus?

A

liver

liver is largely nonfunctional

direct route from umbilical vein to IVC via ductus venosus

17
Q

How does the foramen ovale play a role in fetal blood flow?

A

hole in septum dividing atria, posterior aspect of the right atrium

RtL atrial shunt

bypasses right ventricle

18
Q

How does the ductus arteriosus play a role in fetal blood flow?

A

RtL shunt between pulmonary artery to aorta

19
Q

What is the overall effect of all of the shunts in neonatal blood flow?

A

the total blood flow pumped by the heart passes through different vascular circuits

20
Q

What are the results of the patent foramen ovale?

A

20% of people by age 2yrs, FO doesn’t close

increased right atrial pressure can push open flap

can cause pulmonary hypertension or transient increase in pressure during BM, coughing/sneezing etc.

21
Q

What is the result of a patent ductus arteriosus?

A

heart problem occuring shortly after birth

can be heard as a heart murmur

oxygenated blood in aorta mixes with deoxygenated blood in pulmonary artery

puts strain on heart and increases pulmonary blood pressure

22
Q

When does the kidney begin development?

When is urine produced?

How much of the amniotic fluid is fetal urine?

A

develope at 8wks, done by 36wks

urine production begins between 10-20wks

70-80% of amniotic fluid is urine

23
Q

Renal function matures rapidly during what trimester?

Functional development of the kidney completes closer to what age?

A

Third Trimester

1 month

24
Q

What is the role of the fetal liver?

A
  • poor conjugation of bilirubi, deficient plasma proteins and coagulation factor, poor gluconeogenesis
  • infants use liver’s stored fats and proteins for metabolism until mother’s milk can be provided
25
Q

What is the main form of hemeglobin in the fetus

When are normal adult levels of hemeglobin achieved?

A

Fetal form is HbF (A2Y2) with a higher O2 binding capacity

HbA2 is the adult form and normal levels are reached by 12th week of life

26
Q

What are the main nutrients required by the neonate?

A

Ca and Vit. D for bone development (mother’s milk)

Iron (enough in liver, low in milk but with high bioavailability)

Vit. C (via milk)

27
Q

What are the changes of the neonatal immune system?

A
  • neonate inheritsimmunity from mother but does not make Ab for a while after birth
  • most Ab from mother protect infant for about 6 months
  • baby will make own Ab and gamma globulin around 12-20months
28
Q

What is the anatomy of the mammary gland at birth and at puberty ?

A

At birth, the mammary gland is mainly a lacteriferous duct with few alveoli and will stay in this stage until puberty with minimal branching

At puberty, estrogen will cause lactiferous ducts to sprout and branch and develop alveoli

29
Q

What is the funciton of the alveolar epithelium

What is the function of the myoepithelial cells?

A

luminal epithelium responsible for milk synthesis and secretion

sit between epithelial and basement membrane and contract to move milk from alveoli into ducts

30
Q

How does the mammary gland change during the menstural cycle?

A
  • mammary tissue is exposed to estrogen and progesterone
  • breasts increase in size with adipose and CT deposition
  • can become enlarged, tender, or secrete fluid and then undergo involution at the end of the cycle
31
Q

Define:

Mammogenic

Lactogenic

Galactokinetic

Galactopioetic

A

promote porloferation of alveolar/ductal cells

promote milk produciton by alveolar cells

promote contraction/milk ejection

maintain milk production after it’s been established

32
Q

What are the five ways of milk secretion?

A

secretory pathways

transcellular endocytosis and exocytosis

lipid pathways

transcellular salt and water transport

paracellular pathway

33
Q

How does suckling stimuli (sight or sound of child) effect hormone release?

What happens next?

A

activates afferent neural pathway from breast to spinal cord and then to hypothalamus

Dopamine release is inhibited which results in prolactin release and milk production

34
Q

While suckling increase prolactin and milk production, what is the effect of oxytocin release from the posteiror pituitary?

HOw does inhibition of GnRH play a role in this?

A

interacts with myoepithelial cell resulting in let-down

Inhibition of GnRH production decreases the release of LH and FSH and inhibits the ovarian cycle to prevent another pregnancy

35
Q

How is lactation stopped?

A

when suckling stimulus is discontinued, milk accumulates, causes tissue damage

cell debris is phagocytized

lobular/acinar structures hypotrophy

ductal system predominates

full involution process can take 3 months