ANATOMY

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: -COMMON PRINCIPLES OF ANIMAL CHEMORECEPTION Chemosensory transduction is a process in which chemical stimuli – smells, tastes, nutrients, irritants, and even gases – are recognized and cause changes in the cell membrane properties or release of neurotransmitters and hormones [1].