Learning About PPH

Inside your lungs are millions of very small blood vessels called capillaries. Each one is about as wide as a hair, large enough for blood cells to barely pass through. The inside of the vessel is lined with endothelial cells. The outside is lined with smooth muscle cells. The endothelial cells keep blood from leaking out. The smooth muscle cells allow the capillary to get a bit narrower or wider, depending on how much blood is surging back and forth between the heart and lungs.

Continue...