Final answer:
During the hour that a blood sample is left in a glass tube, clotting occurs, allowing serum to separate from the cellular components of the blood. This serum can be harvested for medical analysis to measure various substances in the blood. Blood collection involves anticoagulants and centrifugation to obtain plasma for tests.
Step-by-step explanation:
When a lab technician collects a blood sample in a glass tube and leaves it undisturbed for about an hour, the blood components separate due to clotting and gravity. During this time, the blood clots, and the serum, which is the liquid portion of the blood without clotting factors, separates from the cellular components. The serum can then be harvested for various medical analyses including measurements of substances like glucose, electrolytes, enzymes, hormones, lipids, and other individual components.
The process of collecting blood for medical analysis often utilizes capillary action in small diameter tubes, involving specific types of collection containers such as tubes containing anticoagulants like lithium heparin, K2EDTA, or dipotassium ethylenediaminetetra-acetic acid (K2EDTA). These anticoagulants prevent clotting, allowing for the collection of plasma, which is blood that retains its clotting factors. After collection, the sample is typically centrifuged to separate the plasma from the blood cells. In some cases, the plasma might be treated further, such as being quenched with methanol, to prepare it for various analytical tests.