Vascular myelopathy later in this article. However, TIAs can result from emboli in calcific aortic disease and aortic coarctation. Spinal arteriovenous malformations (AVMs, or angiomatous malformations) are congenital (from birth) abnormalities of blood vessels. Arteries that directly communicate with veins bypass the capillary network (which has not yet developed) and thus creates a shunt. AVMs appear as a mass of convoluted, dilated vessels. In regards to the spinal cord, they are usually located in the thoracolumbar region (between the thoracic and lumbar regions, 60% of the time), as opposed to the upper thoracic (20%) and cervical regions (approximately 15%). Cervical malformations arise
Pinniped high metabolism. In addition, the blood vessels in their flippers are adapted for countercurrent exchange. Veins containing cool blood from the body extremities surround arteries, which contain warm blood received from the core of the body. Heat from the arterial blood is transferred to the blood vessels, which then recirculate blood back to the core. The same adaptations that conserve heat while in water tend to inhibit heat loss when out of water. To counteract overheating, many species cool off by flipping sand onto their backs, adding a layer of cool, damp sand that enhances heat loss. The northern fur