vitamin D

Level one checkup
...ver-kidney enzymes-urine test-vitamin D ...

What is skin made of?
...sure, and temperature. Makes vitamin D to help keep bones strong. Contains hair follicles (FAA-luh-klz), which grow hair and help repair wounds. What is skin made of? Like all organs in your body, skin is made of different types of cells. Cells are the smallest building blocks of life. You...