Notes

Pulmonary Circulation

Sections

Pulmonary blood circulation

Pulmonary blood flow = cardiac output of the right ventricle.

Key pathways:

  • Right atrium sends deoxygenated blood to the right ventricle, which ejects it through the pulmonary trunk and arteries.
  • Within the lungs, the pulmonary arteries form branching patterns that parallel the tracheobronchial tree.
  • Blood flow travels through the pulmonary capillary networks that surround the alveoli.
  • Carbon dioxide is released from the bloodstream and fresh oxygen enters it.
  • Oxygenated blood returns to the heart via the pulmonary veins, then drains through the left atrium to the ventricle.
  • Upon contraction, the left ventricle sends the oxygenated blood through the aorta to the systemic tissues.

Bronchial circulation:

  • Blood supply to the conducting zone of the respiratory tract; thus, it is the very small portion of total blood flow that does not take part in gas exchange.

Gravitational effects on pulmonary blood flow

  • In upright position, pulmonary blood flow is not distributed evenly throughout the lungs.
  • Gravitational pull results in a lower blood flow at the apex of the lung than at the base.