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.
Spermatogenesis occurs in the Seminiferous tubules in the Testes. http://en.wikipedia.org/wiki/Seminiferou... Oogenesis originates in the germinal epithelium of the ovary. Final product is the mature ovum and three polar bodies.