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.
Plains zebras are 3.6 to 4.8 feet (1.1 to 1.5 m) at the shoulder and weigh up to 770 lbs. (350 kg), according to the African Wildlife Foundation. Habitat. Though they all live in Africa, each species of zebra has its own home area. Plains zebras live in the treeless grasslands and woodlands of eastern and southern Africa. The Grevy's zebra lives in in the arid grasslands of Ethiopia and northern Kenya. The mountain zebra is found in South Africa, Namibia and Angola.