True about fetal circulation –

NEET SS
#1

True about fetal circulation –

  1. Blood in SVC has more oxygen saturation

  2. Pressure in left ventricle is more

  3. Brain receives blood with low oxygen saturation

  4. Heart receives blood with high oxygen saturation

Explanation:

  • Blood in IVC has more saturation than blood in SVC as IVC carries the oxygenated blood of umbilical vein.
  • The left ventricular blood has more oxygen saturation that right ventricular blood because it carries the blood of IVC, while blood in right ventricle is a mixture of blood from IVC and SVC.
  • So, the brain and coronary circulation receive blood with higher saturation (through ascending aorta) than the lower half of body.
  • The left ventricular output is approximately half of right ventricular output because volume of blood reaching in left atrium is considerably lower than volume of blood reaching in right atrium. Infact right atrium is the major source of blood to left atrium.
  • Aorta and pulmonary trunk are connected by ductus arteriosis, and pulmonary trunk has pressure slightly higher or equal to that of aorta → So, blood flows from pulmonary trunk to aorta.
  • The pressure in right and left ventricles are equal.