Final answer:
Fixed orifice devices such as capillary tubes are based on the principle of capillary action for applications like medical blood sample collection. The biology behind capillary types, including fenestrated capillaries, and their applications in different body systems is critical. Furthermore, engineering principles, such as the Venturi constriction, play a role in fluid dynamics similar to capillary action.
Step-by-step explanation:
Fixed orifice devices such as capillary tubes are utilized in various applications, including medical and engineering fields. The principle behind their function is capillary action, which refers to the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to, external forces like gravity. This phenomenon is observed in the medical collection of blood samples, where it draws blood into small-diameter glass tubes, an application that exploits the properties of capillaries to perform tasks like blood analysis conveniently.
In addition to medical uses, understanding capillary action is crucial when discussing different types of capillaries in the human body. For instance, fenestrated capillaries have pores that allow the passage of larger molecules, found in areas like the small intestine and kidneys. On the other hand, precapillary sphincters regulate blood flow entering a capillary.
Engineering applications, such as when dealing with fluid dynamics, the Venturi constriction and different tools like the manometer, apply principles that are akin to those observed in capillary tubes. Venturi constrictions are used to create a drop in pressure that results in 'entrainment', which is the drawing in of a fluid; this is applied in devices like carburetors and aspirators.