Neurovascular bundle fluid and blood, they tend to have large surface area and short diffusion path. Normally, capillaries consist of a central lumen lined with an endothelium, a single layer of smooth epithelial cells. In contrast, deep neurovascular bundles, with arteries in them, have a more complicated composition. Arteries are the vessels that transfer the blood pumped by the heart to the entire body. Arteries have high intraluminal blood pressure, relative to capillaries and veins. To compensate arteries have a smooth muscle and a connective tissue structure outside the endothelium. This composition allows arteries to contract/relax, be flexible under pressure, and transfer
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