These genetic variants are believed to cause changes in the way the bodyâs T cells behave. T cells are immune system cells that normally fight off harmful invaders, such as viruses and bacteria. In people with psoriasis, however, T cells also attack healthy skin cells by mistake. This immune system response results in a range of reactions, including: 1  enlargement of blood vessels in the skin.  increase in white blood cells that stimulate the skin to produce new cells more quickly than usual.
Teeth. Zebra have several types of teeth that help them survive in their habitats. In the front of their mouths, zebra use their strong incisors for biting off grass and other vegetation. In the rear of their mouths, zebra have molars and premolars to grind down their food.
Unlike mountain zebras, other species of zebras need water every day. Mountain zebras can live a maximum of three days without drinking water. Since they have very tough teeth, zebras can tear blades of grass easily, which is too tough for other animals to do. Zebras are known for spending 18 hours a day eating. During the remaining hours, they avoid potential predators, such as lions and hyenas.