1 An unopened container should last for 1-3 months at 40Â°F or less in the refrigerator, but some companies guarantee their product for up to 6 months.  If left in its partially-open original paper wrap, the exposed area of stick butter will begin to harden and smell stale after about a week, as oxygen sets in.
Quick Answer. Humans need a respiratory system because it is made up of organs that allow them to breathe. Breathing delivers oxygen to the body and takes away carbon dioxide. Every cell in the body needs oxygen to obtain energy from food. Continue Reading.
The respiratory system is a collection of organs whose primary function is to take in oxygen and expel carbon dioxide. The major organs of the respiratory system are the lungs, nose, pharynx, and throat.he Muscular system is the organ system whose primary function is movement and flexibility. The muscular system is made up of the muscles that let you move. There are three kinds of muscle in your body. Smooth muscle moves food through the digestive system.