I think the answer is skin. Skin contains sweat glands which secrete a fluid waste called sweat or perspiration; nonetheless, its primary functions are temperature control and release of pheromone. Its role as a part of the excretory is therefore minimal. Additionally, sweating also maintains the levels of salt in the body.
<span>In order to react to the stimulus and catalyze the reaction necessary for the desired outcome, enzyme require a process in which they bind with the substrates in the given experiment, which will then allow the enzymes to undergo the process they are attempting to implement.</span>
The various types of cells making up the structural composition of your body (skin cells, muscle cells, cells of your stomach lining, etc.) are all Epithelial cells. The only other class of cells in your body are Gametes (sperm and egg cells).
