Sensation Of Smell |Olfactory Pathway - Physiology

[Music] in this video let's learn about the sensation of the smell the sensation of the smell is due to the olfactory receptors that are situated in the olfactory mucous membrane which is the modified mucous membrane that lines the upper part of the nostril present in the olfactory mucous membrane at the lining of the upper nostril olfactory mucous membrane consists of about 10 to 20 millions of the olfactory cells by the sustained color cells in the mucosa also contains mucus-secreting bauman's gland the olfactory receptor cell is a bipolar neuron as you can see in the diagram

it is a bipolar neuron the dendrite of this neuron is short and it has an expanded end that is called as the olfactory rod so this is the olfactory receptor cell that is the bipolar neuron this is the supporting sustenticular cell in the olfactory rod and this is the mucous membrane of the upper nostril the old factory rod consists about 10 to 12 cilia these cilia are non-myelinated with a length of 2 microns and these have a diameter of 0.1 microns in this area project onto the mucous membrane the mucus secreted by the bowman's gland

continuously lines the olfactory mucosa and this mucus contains some proteins which increase the actions of the autoreference substances on the receptor cells now let's talk about the olfactory pathway the axons of the bipolar olfactory receptor cells pierce the cribri from plate of the ethmoid bone and they reach the olfactory bulb so this is the cribriform plate of the ethmoid bone and this is the olfactory bulb here the axon synapse with the dendrites of the material cells so these are the metal cells and different groups of these synapses form the globular structures those are called as

the olfactory glomeruli so this is the olfactory glomerulus and the axons of the metal cells leave the olfactory bulb and they form the olfactory tract so this hole is the oil factory tract the old factory tract runs backward and ends in the olfactory cortex so it runs backwards and ends in the olfactory cortex through the intermediate and lateral old factory straya the olfactory cortex include the structures which form the part of the limbic system so these structures are the anterior olfactory nucleus the pre-piriform cortex oil factory tubercle and the amigdala the oil factory transduction is

the process by which the olfactory receptors convert the chemical energy into the action potentials into the olfactory nerve fiber the auditory ferrous substance stimulates the olfactory receptors and only if it dissolves in the mucus that covering the olfactory mucous membrane the molecules of the dissolved substance bind with the receptor proteins of the cilia and they form the substance receptor complex the substance receptor complex activates the adenylyl cyclase that causes the formation of the cyclic amp so it forms the cyclic amp by the activation of the adrenal cyclase and they cause the opening of sodium channels

that lead to inflicts of sodium and generation of the receptor potential the receptor potential causes the generation of the action potential in the axon of this bipolar neuron the odor is classified as follows the first one is the aromatic or the resinous order it is produced by the camphor lavender glow and bitter almonds the second one is the ambrosial order it is produced by the milk the third one is the burning order it is produced by burning feathers tobacco roasted coffee and meat the fourth one is the ethereal order and it is produced by fruits

ethers and beeswax the fifth one is a fragrant or balsamic order it is produced by flowers and perfumes the sixth one is the garlic the garlic order is produced by garlic onions and sulfur the seventh one is the goat this is produced by caproic acid and sweet cheese eighth one is nauseating order it is due to the decayed vegetables and faces the ninth one is the repulsive order it is produced by the bed bug now let's talk about some applied anatomy that is the abnormalities of the olfactory sensation the first one is the anosmia anosmia

refers to total loss of sensation of the smell that is an inability to recognize or detect any order it may be temporary or permanent the temporary enactment is due to the obstruction of nose which occurred during the common cold and nasal sinus in some allergy conditions and the permanent is due to the lesion of the olfactory tract meningitis and degenerative conditions such as parkinsonism and alzheimer's disease and the second one is the hyposmia as the name indicates it is the reduced ability to recognize and detect any order it is the most common disorder and the

orders can be detected only at a higher concentration in this condition and the hyposmia also may be temporary or permanent it occurs due to the same cause of anosmia and the third one is the hyperosmia hyperosmia is the increased or exaggerated olfactory sensation it is also called as olfactory hyperesthesia it occurs in brain injury or epilepsy and some neurotic conditions so the temporary loss of sensations is due to the obstruction of nose by cold nasal sinusitis and some allergic conditions and the permanent enosmia is due to the lesion of olfactory tract meningitis in some degenerative

conditions like the alzheimer's and the parkinsonism so guys this is all about the sensation of the smell and the olfactory pathway if you like this video do subscribe to my channel and do look at some of my recent videos and playlists [Music] you