Urine is made in the kidneys, and travels down two tubes called ureters to the bladder.

In most cases, this involves placing one or more thin tubes, called catheters, into a blood vessel.

These structures are linked together by small tubes called ducts, which carry milk to the nipples.

Then the water travels from the roots through tubes called xylem vessels.

Needles and long, thin tubes called catheters can then be advanced down to the veins in the liver.

Underneath the bars there are long tubes, called resonators, which make the sound louder.

Saliva drains into the mouth through small tubes called ducts.

Life beneath the surface of the ocean in a tiny tube called Pasadena had left them empty in crisis.

They reach the surface in narrow volcanic tubes, called pipes.