  In traditional engines (not overhead cam), the camshaft pushes lifters UP. Lifters push the pushrods UP, but the valves need to be pushed DOWN... so the rocker arm rock â¦ s on a shaft that pushes one side down when the other side goes up. It's not a difficult job.Rocker arms aren't doing the most stressful job in the engine, but they do eventually wear out.ifters push the pushrods UP, but the valves need to be pushed DOWN... so the rocker arm rock â¦ s on a shaft that pushes one side down when the other side goes up. It's not a difficult job. Rocker arms aren't doing the most stressful job in the engine, but they do eventually wear out.
1 These nerve cells are found in a tiny patch of tissue high up in the nose, and they connect directly to the brain.  Gustatory (taste nerve) cells are clustered in the taste buds of the mouth and throat. They react to food or drink mixed with saliva. Many of the small bumps that can be seen on the tongue contain taste buds. These surface cells send taste information to nearby nerve fibers, which send messages to the brain.
Taste Centers in the Brain As explained under Taste Buds, food and substances dissolved in the saliva enter the taste pores where it makes contact with the microvilli of the taste (gustatory cells). This then triggers a depolarization of the taste cell membrane, a subsequent release of neurotransmitters and stimulation of the surrounding nerve fibers. Signals from the nerve fibers of the taste buds travels via cranial nerves VII, IX and X to the tractus solitarius (gustatory area) located in the posterior brain stem. From here neurons transmit signals to the thalamus (ventral posterior medial nucleus).