Bernstein M H, Duran H L, Pinshow B
Science. 1984 Nov 2;226(4674):564-6. doi: 10.1126/science.6436975.
Blood in mouth, nose, and eye tissues of birds cools by evaporation, then flows to a cephalic vascular heat exchanger, the ophthalmic rete. There, acting as a heat sink, blood from the evaporative surfaces cools arterial blood flowing counter-current to it toward the brain. The brain thus remains cooler than the body core. Data for unanesthetized domestic pigeons (Columba livia) suggest that in addition to losing heat, blood perfusing the evaporative surfaces also exchanges oxygen and carbon dioxide with air. In the heat exchanger, this blood apparently gives up oxygen to, and gains carbon dioxide from, arterial blood. The consequent increase in oxygen and decrease in carbon dioxide in the brain's arterial blood enhance diffusion of these gases in, and oxygen supply to, the brain. Such events may help birds maintain the brain's oxygen supply during the high systemic demand of exercise and at the reduced oxygen availability of high altitude.
鸟类口腔、鼻腔和眼部组织中的血液通过蒸发冷却，然后流向头部血管热交换器——眼 rete。在那里，作为一个散热器，来自蒸发表面的血液冷却与其逆流流向大脑的动脉血。因此，大脑的温度始终低于身体核心温度。针对未麻醉的家鸽（Columba livia）的数据表明，除了散热外，流经蒸发表面的血液还与空气进行氧气和二氧化碳的交换。在热交换器中，这些血液显然将氧气释放给动脉血，并从动脉血中获取二氧化碳。大脑动脉血中氧气的增加和二氧化碳的减少会增强这些气体在大脑中的扩散以及对大脑的氧气供应。这些过程可能有助于鸟类在运动时全身对氧气的高需求以及高海拔地区氧气供应减少的情况下维持大脑的氧气供应。
