BIOL 221 Lecture Notes - Lecture 7: Bronchiole, Partial Pressure, Vasodilation
3 Mar 2020
School
Department
Course
Professor
Document Summary
Due to factors that affect the ability to ventilate individual alveoli (e. g. , local mucus accumulation or edema) the partial pressures of oxygen and carbon dioxide in individual alveoli might not be the same throughout the lungs. In addition, blood supply to some areas may be decrease. For example, a pulmonary embolism will decrease blood flow downstream to the capillaries associated with the alveoli. Ventilation-perfusion coupling matches ventilation of alveoli to blood supply. It ensures that more blood goes to alveoli than are well- ventilated and that more air goes to areas in which blood supply is maintained. Diameters of arterioles and bronchioles can be controlled due to the smooth muscle in their walls. The muscle responds to partial pressures of oxygen and carbon dioxide levels. The partial pressure of oxygen in the airway affects arteriolar diameter. When po2 decreases, the vessels constrict to direct blood away from alveoli in which po2 will be less than normal.
