GENERAL HISTOLOGY

Detailed explanation-1: -Olfaction: In terrestrial vertebrates, olfaction occurs in the nose. Volatile chemical stimuli enter the nose and eventually reach the olfactory epithelium which houses the chemoreceptor cells known as olfactory sensory neurons often referred to as OSNs.

Detailed explanation-2: -Chemoreceptors are proteins or protein complexes that bind molecules detected at distance and generally at low concentration (olfaction) or molecules detected at proximity and often at higher concentrations (gustation), respectively volatile and not volatile for organisms living in the aerial phase.

Detailed explanation-3: -Decreased Arterial Oxygen Stimulates the Chemoreceptors When the oxygen concentration in the arterial blood falls below normal, the chemoreceptors become strongly stimulated.

Detailed explanation-4: -All animals and microorganisms such as bacteria exhibit this latter type of chemoreception, but the two commonly recognized chemosensory systems are the senses of taste, or gustation, and smell, or olfaction.