The endless chain of command

Having a job is tiresome. My job is definately not the hardest job in the world, it's not complicated nor is it challenging. But at times there are factors that contribute to massive times of stress. Today was no exception. During a party of 12, we got over loaded with customers. Normally that isn't a huge issue, but they kept coming...and coming...and coming. We got behind, next thing you know there are 10 orders in the window and some pretty pissed off customers. During these times I just breath and take it in stride...no big deal. But the thing that frustrates me to no end is when I not only have to do MY job...but someone else's. My manager cut her hand with a steak knife...it could possibly have required two stitches, it's on the palm of her hand. Yes, I realize it probably hurts...but you didn't loose your hand...you CAN still function. I worked for 6 weeks with a broken foot. Surely she could work with a 1/2 inch cut on her hand. Everything being left up to me is frustrating...I do not get paid enough for EVERYTHING to be left on my shoulders. But, I suck it up. I want to advance where I am at, and it is money. I just get frustrated.