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 main job of the Respiratory System is to provide the blood with oxygen, so the rest of the body can get oxygen too. The body does this by breathing. Our body breathes in oxygen, and breathes out carbon dioxide. By changing these gases in our bodies, the blood gets oxygen. Molecules of oxygen and carbon dioxide are passively exchanged. The Respiratory System gets oxygen through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters through the nose and mouth and travels through the larynx and the trachea. The inhaled oxygen then follows a path through your body. At the same time, the blood in the veins releases carbon to alveoli.