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 Water is the second factor necessary for animals to survive. 2  Make a list of different areas water can be obtained by animals. 3  Puddles, springs, streams, and ponds are places where animals can get water.  4 We've named two factors necessary for animals to survive: food and water. 5  There are two more. Omnivores can live in many places because they eat both plants and animals. 2  Have students name examples of each group. 3  List on overhead.  4 Now that we've discussed that animals need food to survive and the different types of food animals need, who can name the second factor necessary for animals to survive.