See cardiorespiratory endurance. L-carnitine is available as a dietary supplement. Formed from the essential amino acids lysine and methionine. It is commonly used for palpating the pulse rate. The enveloping capsule of a cell, composed primarily of a lipid bilayer, but including carbohydrates and proteins in addition to the fats and cholesterol that make up the lipid bilayer.
Cholesterol is vital to life and is found in all cell membranes.
It is necessary for the production of bile acids and steroid hormones. Dietary cholesterol is found only in animal foods. Abundant in organ meats and egg yolks, cholesterol is also contained in meats and poultry. Vegetable oils and shortenings are cholesterol-free. Most of the cholesterol that is found in the blood is manufactured by the body, in the liver, at a rate of about 800 to 1,500 milligrams a day.