Mine plus I dont get it lol
Waste products are constantly being produced by the body and must therefore be excreted. If they are not, they will increase in concentration and may interfere with chemical reactions or damage cells. Waste products that must be removed include carbon dioxide and urea.
A motor unit is made up of the motor neuron and a skeletal muscle fibers innervated by the motor neuron axonal terminals. when a motor unit is activated all of its fibers contract. In vertebrates,the form of a muscle contraction is controlled by the number of activated motor units.