Question

Compare/Contrast the Main Olfactory System to the Accessory Olfactory System from detection to perception and consider how they work separately and together

Answer 1

Olfactory system deals with olfaction ( sense of smell ) .

It is made up of main olfactory and acessory olfactory system .

In humans mostly main olfactory system is functional and it detects volatile smells and mammals and reptiles accesory olfactory system works and it detects non volatile smells

Olfactory receptors present in nasal cavity senses the odorant smells .

Ofactory epithelium is present in olfactiry receptors . The human olfactory epithelium are bipolar olfactory sensory neurons interspersed with glia-like supporting (sustentacular) cells and basal stem cells.

Each olfactory neuron has a short, thick dendrite that projects into the nasal cavity where it terminates in a knob containing 6–12 cilia.

The cilia contains specific receptors for odorants (odorant receptors).

The axons of the olfactory sensory neurons pass through the cribriform plate of the ethmoid bone and enter the olfactory bulbs.

In the olfactory bulbs, the axons of the olfactory sensory neurons (first order nerve) contact the primary dendrites of the mitral cells and tufted cells to form anatomically discrete synaptic units called olfactory glomeruli.

These mitral cells and tufted cells (second order neurons) directly project to the olfactory cortex without any relay to thalamus.

Regions of the olfactory cortex— anterior olfactory nucleus, olfactory tubercle, piriform cortex, amygdala, and entorhinal cortex. From these regions, information travels directly to the frontal cortex or via the thalamus to the orbitofrontal cortex.

As in the main olfactory system, the axons of these sensory neurons project from the chemosensory organ vomeronasal organ to the accessory olfactory bulb eg in reptiles and mammals .

Unlike in the main olfactory system, the axons that leave the accessory olfactory bulb do not project to the brain's cortex but go to the amygdala and bed nucleus of the stria terminalis, and from there to the hypothalamus.

And aggessive charcter and matting nature of reptiles and mammals is through non volatile substance that their acccesory olfactory system detects .