All of these must pass through the cell membrane. Transport may occur by diffusion and osmosis across the membrane. It can also occur when a vescicle attaches to the cell membrane from the inside and then opens to form a pocket, expelling its contents to the outside. This may be called exocytosis.ll of these must pass through the cell membrane. Transport may occur by diffusion and osmosis across the membrane. It can also occur when a vescicle attaches to the cell membrane from the inside and then opens to form a pocket, expelling its contents to the outside. This may be called exocytosis.
Many enzymes that occur in certain tissues are found in blood plasma at higher levels when the cancer involves that tissue. Enzymes are usually measured by determining the rate at which they convert a substrate to an end product, while most tumor markers of other types are measured by a test called an immunoassay.
Liver enzyme blood tests are often performed as part of a more comprehensive test called a liver function test. The reason for this is because liver enzyme results only tell part of the story related to liver health and condition. Liver enzyme results measure enzymes the organ produces in response to damage or disease.hile the measurement of liver enzymes is frequently part of a laboratory blood test known as the liver function test, testing for liver enzymes may also be performed independent of other testing.