fetal breathing-like movements (FBI) are practiced in utero by \____ weeks gestation
17
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why are fetal breathing movements necessary in utero?
for cell kinetic regulation (cell proliferation and death) via the expression of growth factors like insulin and thyroid transcription factor
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lack of fetal breathing movements can cause __1__, because __2__
1. pulmonary hypoplasia
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2. although type II pneumocytes can synthesize surfactant proteins, they can't store and release surfactant - this renders type I pneumocytes useless bc they can't flatten to allow gas exchange
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fetus obtains O2 from __1\__ via the __2\__ with a pressure gradient difference of __3\__ mmHg partial pressure of O2 in maternal blood and __4\__ mmHg in fetal blood
1. maternal circulation
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2. placenta
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3. 50
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4. 30
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fetal hemoglobin carries up to __1\__ more O2 than adult and makes up __2\__ of circulating hemoglobin in fetus and newborn
1. 30%
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2. 70-90%
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highest concentration of circulating O2 goes where in the fetus?
brain and heart
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2 important facts about fetal hemoglobin
1. it has a higher affinity for oxygen and improves oxygen intake from mother
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2. it decreases the unloading of oxygen at the tissue level (to overcome this and expedite oxygen release at tissue level, oxygen release is increased by fetal acidosis)
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normal fetal pH
-7.25-7.35
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-lower than adult pH to expedite oxygen release at the tissue level
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respiratory preparation for birth
-FBM and lung fluid production decrease 24-36 hours prior to onset of true birth
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-surfactant peaks at 28-32 weeks gestation
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-administration of steroids can stress surfactant production and increase oxygenation in preterm lungs (only between 24-34 weeks)
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-steroid admin. can help decrease bleeding in ventricles of the brain
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compression and recoil of thorax
a mechanical stimulus to initiate newborn respirations
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crying partially closes __1\__ and increases __2__
1. glottis
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2. positive intrathoracic pressure
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-mechanical stimulus to initiate newborn respirations
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movement of __1\__ down/flat increases __2__, which causes what?
1. diaphragm
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2. negative intrathoracic pressure
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-causes passive fluid absorption
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-mechanical stimulus to initiate newborn respirations
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alveoli in lungs __1__,which increases...
1. expand and are more permeable
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-increases O2 concentration
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-mechanical stimulus to initiate newborn respirations
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increase in what two things mechanically stimulate initiation of respirations in newborns?
-increase in functional residual capacity (FRC) of newborn lungs
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-increased absorption of lung fluid via the capillaries and lymphatic system
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what facilitates cessation of placental circulation?
umbilical cord clamping
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chemical stimuli that initiates respirations in newborns
-increase in CO2
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-decrease in O2 and pH
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-decrease in pulmonary vascular resistance increases gas exchange
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-dilation of pulmonary vessels increases pulmonary blood flow
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sensory stimuli that initiates respirations in newborns
-warm, dry, and stimulate
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-lights, temperature changes, noise
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cord clamping increases \____ in cardiovascular adaptation transition
systemic vascular resistance
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ductus arteriosus
-protects lungs against circulatory overload
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-blood flows across ductus and into the descending aorta
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Flashcard (63)