Supporting cells.
These cells are called sustentacular cells or supporting cells. They surround and support the olfactory receptor cells in the olfactory epithelium. They provide physical support, nourishment, and electrical insulation to the olfactory receptor cells, helping to maintain their function.
Olfatory is the CN 1, Optic nerve is the Second.
Tobacco smoke affect the sensory organs by promoting inflammation in the upper respiratory system which comprises nasal sinus, pharinx, which damage the olphatory cells in that system thus causing a condition called anosmia. Then, the sense of smell is affected by smoking, because the olfatory cells can't communicate with the brain receptors of smelling.
Pits can't really be "trained" they are used almost exclusively as catch dogs in case of hogs but pitbulls will hunt smaller animals. Pits have better olfatory than the smelling breeds and have better stanima than hunting breeds. An adult pitbull will smell and run after an animal and will hunt it with no training on your part. If the pitbull is well trained, you can command him not to catch that animal or go ahead if is ok.
In HUMANS, mucus acts as an important unspecific form of defense against pathogens preventing them from entering your body and coating our stomach walls which prevents the highly acidic acids in our stomach from digesting itself.In ANIMALS, mucus has many roles.defense against predators Ex. hagfishmotion Ex. snailshomes Ex. cave swiftlethunting Ex. New Zealand glowwormbungee (escape) cord Ex. banana slug