Sharks have skin covered in millions of tiny teeth-like scales that point to the tail. If you rub along a shark towards the tail, it would feel smooth, but if you rub the other way, it would be rough. Sharks' teeth can be 20 times as big as human teeth and they can grow back if they are lost. Fins
Vertebrobasilar insufficiency is a condition characterized by poor blood flow to the posterior (back) portion of the brain, which is fed by two vertebral arteries that join to become the basilar artery. Blockage of these arteries occurs over time through a process called atherosclerosis, or the build-up of plaque.
vertebrobasilar insufficiency (verËÂ·t Â·brÅÂ·bÄËÂ·z Â·ler inËÂ·s Â·fiËÂ·sh nÂ·sÄ) , n a disorder caused by decrease of blood flow in the vertebral or basilar arteries due to atherosclerosis or compression placed on the external wall of the arteries. Symptoms may include loss of vision, dizziness, or nausea.