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.
RESPIRATORY SYSTEM. The respiratory system provides your body cells with the oxygen they need and rids them of carbon dioxide, a waste product. Playing a central part in this process are the lungs, two organs in the chest that work closely with the blood circulation. BREATHING is the cycle of moving air into and out of the lungs. Structures in the respiratory system are also vital to SPEECH. Blood is carried from the heart to the lungs by the pulmonary arteries. They are the thick red vessels at the centre of this photograph of a resin cast of two lungs.