Exhaust system affects fuel efficiency. If you notice you have to fill up your gas tank more often than normal, have your exhaust system checked out by a muffler repair shop. Similar to the vibrations, increased fuel use is a sign something is wrong with your car. When the exhaust leaks, your engine works harder.
Temporal summation is the linear addition of graded potentials that overlap in time; that is, a second potential arrives before the first one from that source has finished. Spatial summation occurs when there is simultaneous arrival of graded potentials originating from more than one synaptic input. Summation occurs at the trigger zone. Typically a multipolar neuron has many active synapses at a given time, with multiple potentials being produced at each.
Desquamation (say des-kwa-MA-shun) is the natural process in which skin cells are created, sloughed away and replaced. Sometimes called cell turnover, desquamation happens every second of every single day, without you even noticing! The desquamation process happens in the outermost layer of the skin -- the epidermis. The epidermis itself has 4 unique layers. Each of these layers plays a role in desquamation. New skin cells are created in the stratum germinativum, which is the the deepest layer of the epidermis. This layer is also called the basal layer. Skin cells begin their life as a single layer of thick, column-shaped cells. These cells are responsible for creating every cell of your skin.