For this telescope, the lenses are a concave convex (one side curved out and the other curved in) and a plano concave (one flat side and one side curved in). The plano concave lens is used as the eyepiece with the plano (flat) side facing the eye.
BUN redirects here. For other uses, see Bun (disambiguation). The liver produces urea in the urea cycle as a waste product of the digestion of protein. Normal human adult blood should contain between 6 and 20 mg of urea nitrogen per 100 ml (6â20 mg/dL) of blood.
Blood urea nitrogen (BUN) measures the amount of urea nitrogen in bloodstream. Urea is formed in liver as the end product of protein metabolism and digestion. Urea is transported to the kidneys for excretion. A normal range for blood urea nitrogen is generally 8 to 24 mg/dl for adult males and 6 to 21 mg/dl for females.Generally, a high blood urea nitrogen level means that the kidneys are not performing well, particularly if the result is above 50mg/dl.rea is formed in liver as the end product of protein metabolism and digestion. Urea is transported to the kidneys for excretion. A normal range for blood urea nitrogen is generally 8 to 24 mg/dl for adult males and 6 to 21 mg/dl for females.