The tubing that you are talking about is called "secondary"-- it is used in conjunction with primary tubing. Secondary tubing is used for giving piggy back medications such as antibiotics.
In the recent past, we used needles on the end of the secondary tubing to insert into the primary tubing at the different ports, then usually put a piece of tape around it so that it would not get pulled out. Nurses would get stuck, etc. Now they have what is called the "needleless" system, where the tubing can attach directly without the needle.
Hope that this helps and good luck with your clinicals.