What four factors protect the skin from colonization of most bacteria?

What is the most common twin combination? What is VDP DBS on the back of a AV receiver stand for? Halo traction in scoliosis? What is a hereditary risk factor? What does Tourette syndrome do to the body? If two different brands of home pregnancy tests say positive then am I pregnant? How is Sideroblastic Anemia caught? What is irritable bowel symdrome? My left eye started twitching now the left side of my face is numb and i cant blink my eye how do i fix this? How can you fight food poisoning? What does it mean i am 9 months pregnant and seeing blood when you go to the washroom? What is the definition of non communicable diseases? You have took a pregnancy test with a faint positive and i was a day late and now i am bleeding? How does Physical barriers that help prevent an individual from contracting diseases include .? Cells that produce this substance degenerate after tooth eruption? How are the mucosa and sub-mucosa of the small intestine adapted for both digestion and absorption? What are the names of the cartilages that support the trachea? Your gums under one tooth that has a procelain crown is turning black and it feels like it's burnt. What is going on? How do you lose your voice? What are 'prokaryotic organisms' What are some examples?