Blood collection tubes must be drawn in a specific order to avoid cross-contamination of additives between tubes. The recommended order of draw for plastic vacutainer tubes is: 1  First-blood culture bottle or tube (yellow or yellow-black top). 2  Second-coagulation tube (light blue top). 3  Third-non-additive tube (red top).
A thermocouple produces a voltage when the temperature of one of the contact points differs from the temperature of another, in a process known as the thermoelectric effect.he wires that make up the thermocouple must be insulated from each other everywhere, except at the sensing junction. Any additional electrical contact between the wires, or contact of a wire to other conductive objects, can modify the voltage and give a false reading of temperature.
In this lesson, we'll discuss how the skin detects changes in temperature through the use of specialized receptors known as thermoreceptors. Thermoreceptors and Temperature. Thermoreceptors are specialized nerve cells that are able to detect differences in temperature. Temperature is a relative measure of heat present in the environment. Thermoreceptors are able to detect heat and cold and are found throughout the skin in order to allow sensory reception throughout the body. The location and number of thermoreceptors will determine the sensitivity of the skin to temperature changes.