Endo-Repro L27 Fetal Organ System Flashcards
The intrauterine environment relieves foetal organs of the need to perform certain functions:
- Placenta
- Weightless state of foetus
- Isothermal environment
Foetus is not dormant →
→ Foetal systems must develop and mature to sustain life immediately after birth.
Adaptations of the fetal cardiovascular system: Ventricles
Two fetal ventricles pump in parallel, not series.
Adaptations of the fetal cardiovascular system: Four foetal shunts
- Placenta
- Ductus venosus - liver
- Foramen ovale
- Ductus arteriosus → pulmonary artery to aorta
Adaptations of the fetal cardiovascular system: Foetal shunts ensure
Optimal distribution of oxygenated blood to head and body
Changes in foetal circulation at birth:
At birth, the four fetal shunts close to replace the placental circulation with the pulmonary circulation:
- Placenta ceases to deliver oxygenated blood to newborn
- Pulmonary vascular resistance falls dramatically
- Pressure on the right side of the heart decreases
- Pressure on the left side of the heart increases
- Flap valve closes foramen ovale
- Ductus venosus ceases to carry blood to the heart
- Ductus arteriosus contracts and close
Respiratory System: fetal breathing
- Fetal breathing movements:
a. Are Rapid and irregular
b. Occur only during REM sleep
c. Are diaphragmatic
d. Move amniotic fluid in and out of the lungs
Functions of fetal breathingh
a. Practice
b. Distend the lungs and stimulate growth
Maturation of Lung function:
- Fetal lungs undergo major structural changes during pregnancy
- Near birth, the pressure required to expand the lung decreases
- Surfactant:
a. Phospholipid synthesized in lung
b. Defiency causes respiratory distress syndrome
- Water reabsorption: in fetus
a. Switch from Cl- secretion to Na+ absorption
Foetus salt and water reabsorption
CFTR-driven salt and water secretion.
Neonate salt and water reabsorption
Neonate:
Gastrointestinal activity during pregnancy
- The feotus swallows large volumes of amniotic fluid daily.
- Swallowed salt, water, and small molecules are absorbed in the small intestine
Meconium formed from
Swallowed debris and large molecules accumulate in the large intestine to form