Crest dispensers

Usage examples of tubes.

In the trachea, bronchi, and larger bronchial tubes, the stiffness is supplied by rings of cartilage, while in the smaller tubes this is replaced by connective and muscular tissue.

These convey to the lungs blood that has already been supplied with oxygen, passing it into the capillaries in the walls of the bronchi, bronchial tubes, and large blood vessels, as well as the connective tissue between the lobes of the lungs.

Demonstrate the trachea, bronchi, and the bronchial tubes, and the general arrangement of pulmonary arteries and veins.

The heart, which is the chief organ for propelling the blood, acts as a force pump, while the arteries and veins serve as tubes for conveying the blood from place to place.

The arteries and veins are similar in structure, both having the form of tubes and both having three distinct layers, or coats, in their walls.

As a result these tubes stand open when empty, whereas the veins collapse.

Since pressure is necessary for moving the blood, these tubes must connect with the source of the pressure, which is the heart.

The ventricles keep a pressure on the blood which is sufficient to force it through all the blood tubes and back to the auricles.

In the capillaries the blood takes on and gives off materials, while the arteries and veins serve chiefly as tubes for conveying the blood from one system of capillaries to another.

Connect a rubber tube with each opening, letting the tubes reach into two tumblers containing water.

Now compress the tube with the hand, noting that the water rises in both tubes, being pushed in both directions.

These keep it from coming in contact with any of the cells of the body except those lining the tubes themselves.

A considerable amount of the material absorbed from the food canal also enters the lymph tubes, but this passes into the blood before reaching the cells.

Connecting with the lymph spaces on the one hand, and with certain blood vessels on the other, is a system of tubes that return the lymph to the blood stream.

They consist of slender, thin-walled tubes, which resemble veins in structure, and, like the veins, have valves.