The outlines of anatomy, physiology, and hygiene Being an edition of The essentials of anatomy, physiology, and hygiene, rev to conform to the legislation making the effects of alcohol and other narcotics upon the human system a mandatory study in public schools . ^ the specialsensation of smell. The nerve is distributed to theupper third of the nasal passages, and the rest ofthe interior of the nose is supplied by nerves ofordinary sensation (Fig. 64). The amount of any substance required to affectthe sense of smell is inconceivably minute. There. Fig. 64.—The interior of the left nasal passa
The outlines of anatomy, physiology, and hygiene Being an edition of The essentials of anatomy, physiology, and hygiene, rev to conform to the legislation making the effects of alcohol and other narcotics upon the human system a mandatory study in public schools . ^ the specialsensation of smell. The nerve is distributed to theupper third of the nasal passages, and the rest ofthe interior of the nose is supplied by nerves ofordinary sensation (Fig. 64). The amount of any substance required to affectthe sense of smell is inconceivably minute. There. Fig. 64.—The interior of the left nasal passage. The fan-like expansion ofnervous fibers is the olfactory nerve. The other nerves shown are nervesof ordinary sensation. is no chemical or physical means known by whichit can be detected in many cases. A grain of muskwill perfume a room for months, and lose nothingapparently in weight. TOUCH—TASTE—SMELL. 281 In order to affect the sense of smell, the odorousair must be drawn through the nose. If the airin the nasal passages remains stationary, we smellnothing. This is the reason why closing the nostrilsprevents our appreciating aromatic substances in themouth. For this reason, also, we sniff at whateverhas a delicate or faint odor, and, by increasing therapidity of the air-current through the nose, we addto our appreciation of the odor.^ This is very no-ticeable in the lower animals. It is necessary to distinguish between substanceswhich really affect the sense of smell and thosewhich merely irritate the mucous membrane. INIanysubs
Size: 1574px × 1587px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., booksubjecthumananato, booksubjecthygiene, booksubjectphysiology
