Question

In the olfactory system,

A. each glomerulus in the olfactory bulb receives synaptic inputs from the primary olfactory receptor neurons of one particular type, among the thousand or so different types of receptor cell found in the olfactory epithelium.

B. primary olfactory receptor neurons have axons that project directly to the brain, where they make synapses onto neurons of the olfactory bulb.

C. olfactory stimuli depolarize primary olfactory receptor neurons by means of G-protein coupled receptor molecules located in the cilia of the receptor neurons.

D. all of the above are correct.

Answer 1

Answer is D .all of the above

Olfactory receptors are the first-order neurons of the olfactory pathway. Each olfactory receptor is a bipolar neuron with an exposed knob-shaped dendrite and an axon projecting through the cribriform plate and ending in the olfactory bulb. The parts of the olfactory receptors that respond to inhaled chemicals are the olfactory hairs, cilia that project from the dendrite.Chemicals that have an odor and can therefore stimulate the olfactory hairs are called odorants. Olfactory receptors respond to the chemical stimulation of an odorant molecule by producing a generator potential, thus initiating the olfactory response.
Olfactory receptors react to odorant molecules in the same way that most sensory receptors react to their specific stimuli: A generator potential (depolarization) develops and triggers one or more nerve impulses. In some cases, an odorant binds to an olfactory receptor protein in the plasma membrane of an olfactory hair.

The olfactory receptor protein is coupled to a membrane protein called a G protein, which in turn activates the enzyme adenylate cyclase

The result is the following chain of events: production of cyclic adenosine monophosphate (cAMP) n opening of sodium ion (Na) channels n inflow of Nandepolarizing generator potential n generation of nerve impulse and propagation along an axon of the olfactory receptor.