Capillaries. 1. Microscopic vessels that carry blood from small arteries (arterioles) to small veins (venules). 2. They connect arterioles to venules. 3. The capillary wall is composed of only single layers of cells (endothelium) 4. They have no tunica media or adventitia. 5.. The tunica media (middle layer) contain more elastic fibers (hence the name elastic) than smooth muscle smooth muscle 2. These vessels will conduct (hence the name conducting) blood to the muscular arteries 3. They are designated large because the diameter is larger than the medium sized arteries.
Running shoes may put more strain on your joints than running barefoot or even walking in high heels, a recent study suggests. Humans could perhaps run as fast 40 mph, a new study suggests. Such a feat would leave in the dust the world's fastest runner, Usain Bolt, who has clocked nearly 28 mph in the 100-meter sprint.
The World's Fastest Man Meets the World's Slowest Woman. In Beijing the focus has moved from the pool to the track, where Usain Bolt breezed through the 100-meter dash so easily he looked like an Olympian god running against mortals. No doubt he's now the world's fastest human. Another Olympian who held that title was Bullet Bob Hayes, who later played for the Dallas Cowboys. He was crowned world's fastest human at the 1964 Olympics in Tokyo where he won gold medals in the 100-meter dash and as anchor of the 400-meter relay. Like Bolt, Hayes blazed through the dash leaving his competitors in the dust.