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.
BUN is a measure of kidney function. A high level may indicate that the kidneys are functioning less than normal. Normal Values: 8-25mg/100ml (USA) 2.9-8.9 mmol/L (International). This test measures the amount of carbon dioxide in the blood.Most carbon dioxide is present in the form of bicarbonate, which is regulated by the lungs and kidneys.UN is a measure of kidney function. A high level may indicate that the kidneys are functioning less than normal. Normal Values: 8-25mg/100ml (USA) 2.9-8.9 mmol/L (International). This test measures the amount of carbon dioxide in the blood.