Why the capillaries have a single layer of endothelium?

When should a bipolar ESU be used once the brain has been exposed? Which structure is the site of nutrient and gas exchanged between the mother and growing fetus? Why are two pairs of ribs called the 'floating ribs'? After heavy headaches over a few days followed blurred vision in one eye? Do people with autism have trouble concentrating or paying attention? Can a pinched nerve cause your legs to swell? Is prader -willi syndrome recessive or sex transmited? What causes urine dark yellowish? Why does energy tend towards disorder? How do you get a seizure? Could the same genetic condition that causes sickle cell anemia can also protect against any other diseases? Can ecp tablet cause death or internal bleeding? What are Napkin Pirates Is it really an STD? Can giardia be transmitted by a bite? How long have phobia's been around for? How do you know if im a bulimic. how many times do you have to throw up in order for you to be consider one? Why do you have a feeling that you need to pee when i don't? How many hours sleep does an 11 year old boy need who plays football for 2 hours 3 nights a week? Is it healthy to jog during H1N1 season? Can Cauda Equina affect your bowel?