So the more carbon dioxide we have in the blood, the less likely that hemoglobin will actually bind onto that oxygen. And conversely, the less CO2 we have in the blood, the more likely our oxygen, our hemoglobin, will actually bind to oxygen. So what exactly do we mean by double bore effect? Well, let's take a look at the following diagram to see what the double bore effect is. So, let's suppose that this purple line is basically our placental membrane. And our gas exchange takes place across the placental membrane, which is basically this coryonic membrane shown right here in purple.