234. Cardiovascular System Flashcards
What is the first functional organ of the embryo?
The heart
The heart forms between the second and eighth weeks of life.
During which day does cardiac looping occur?
Day 23
What are the four initial heart structures formed from the straight heart tube?
- Truncus arteriosus
- Bulbus cordis
- Ventricle
- Atrium
What is fetal circulation compared to maternal circulation?
Relatively hypoxic
What are the three fetal shunts?
- Foramen ovale
- Ductus arteriosus
- Ductus venosus
What triggers the transition to neonatal circulation at birth?
Clamping of the umbilical cord and inflation of the lungs
What happens to pulmonary vascular resistance (PVR) at birth?
Decreases
What is the patent foramen ovale (PFO) closure dependent on?
Left atrial pressure becoming higher than right atrial pressure
What factors keep the ductus arteriosus patent in utero?
- Hypoxia
- Mild acidosis
- Placental prostaglandins
What conditions can increase pulmonary pressures and revert to fetal circulation?
- Hypothermia
- Hypercarbia
- Acidosis
- Hypoxia
- Sepsis
What is a significant characteristic of the neonatal myocardium?
Less contractile elements and more connective tissue than adults
How does the neonatal heart’s cardiac output depend on heart rate?
It is dependent on heart rate due to fixed stroke volume
What is the oxygen consumption comparison between neonates and adults?
6 mL/kg in neonates vs. 3 mL/kg in adults
What effect do anesthetics have on myocardial oxygen consumption in neonates?
Most anesthetics cause an overall reduction in heart rate and cardiac output
What role does the parasympathetic system play in heart innervation early in life?
It plays a major role as the sympathetic nervous system is still developing
