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.
1 Three species of zebras live in Africa. 2  The species are the Plains Zebra, which is the most common one, the Mountain Zebra, and the Grevy Zebra. 3  Zebras are a short, stocky animal that is generally about 8 feet long and stands between 4 and 5 feet at the shoulder. The species are the Plains Zebra, which is the most common one, the Mountain Zebra, and the Grevy Zebra. 2  Zebras are a short, stocky animal that is generally about 8 feet long and stands between 4 and 5 feet at the shoulder. 3  They can weigh up to 650 pounds.