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 ischemia, which is also referred to as vertebrobasilar insufficiency (VBI) and commonly called beauty parlor syndrome (BPS), describes a range of conditions that cut off the blood supply to the back of the brain. These conditions can have a negative effect on automatic brain functions such as respiration.