21 Anatomy and Physiology 2 Guide Test 2 The Chemical Senses 1 Define and identify the anatomy of the olfaction receptor cells and epithelium Olfaction is the technical name for smell and along with gustation contains chemoreceptors to transmit information to the brain The receptors for olfaction are aroused by air chemicals which get dissolved in the nasal membrane Olfaction reception is from the chemicals that dissolve in the membrane The roof of the nasal membrane is called the olfactory epithelium and is classified as a pseudostratified epithelium In this area there are three types of cells to know the receptors the supporting and the basal cells The receptor cells are bipolar neurons from a p 1 these are specialized neurons with one dendrite and one axon that end at the olfactory cilia The cilia increase the surface area cilia always increase surface area and are in a lot of places a pattern you ll notice in the body and are covered by the mucus that the supporting cells secrete This mucus cleanses the air by capturing bacteria Then the filaments of the nerves are replaced every 30 60 days via the basal cells These receptor cells have the potential to distinguish up to 10 000 different odors and these receptors are stimulated themselves by around 1 000 smell genes in our nose There are also pain receptors as we know from having an irritant in our nose for example The supporting cells are lined along the cilia and these secrete the mucus that captures bacteria in the air The cilia are actually your nose hairs if this will make it easier to understand and the mucus when you sneeze for example is what captures bacteria Then the basal cells simply replace the nerve filaments every 30 60 days Basal cells regardless of where they are in the body replenish cells 21 2 Explain in detail the transduction of smell and its process and adaptation through the somatosenstory system Say you breath in a chemical in the air this is how the signal is processed to your brain First the odor whatever it is will bind to a receptor protein Once bound this is activate a G protein cAMP cascade This is that second messenger system The G protein will activate an adenylate cyclase which will activate a cAMP and this cAMP will allow sodium and calcium to flow into the cell to cause the cell to depolarize and send off an AP because positive charge is entering the cell This AP travels from the bipolar nerves to the secondary neurons called the mitral cells which are in the glomeruli Depending on the order a certain glomeruli will respond So the AP will then depolarize the mitral cell and this mitral cell will transmit the AP down the olfactory tract to the thalamus or the hypothalamus amygdala or the limbic system so it will reach somewhere in the brain This is how every smell will reach the brain The odor will bind to a receptor activate a G protein to activate cAMP cause sodium and calcium to enter and depolarize the cell and cause an AP to travel to a specific glomeruli for that odor The mitral cell inside the glomeruli will then send an AP to a region in the brain The nose is very sensitive meaning only a few molecules have to be present to cause a signal As we all know the nose adapts very quickly to a smell meaning if you smell a horrible smell for like a min or so you will get used to it if you stay in the same room 3 Describe and locate the types of taste buds associated with gustation Gustation is the technical term for taste and we have taste buds or receptors on our tongue lining our cheeks and in our pharnyx The ones we care about on our tongue are housed in the papillea which is contributes that abrasive feel on our tongue These are named based on their location the fungiform papillae are on the top of the tongue the foliate are on the lateral surface and the circumvallate are all the way on the back of the tongue 4 Describe the gustatory cells 21 These taste buds are composed of around 50 100 cells composed of two types the gustatory cells and the basal cells The gustatory cells are like the olfactory receptor cells these are the cells that are going to conduct the AP to the brain Like the mucus in olfaction gustatory cells are surrounded by saliva So these cells will conduct an AP through a bipolar neuron to the brain Depending on the type of the gustatory cell it can either release serotonin or it will use ATP Basal cells simply replace the gustatory cells every 7 10 days as compared to the olfactory basal cells which replace cells every 30 60 days Taste buds are introduced to heat and need to be replaced more than olfactory cells 5 Name the major types of taste stimuli and where they most commonly occur Our taste buds have 5 different classes of stimuli and you need to know them and where they occur on the tongue Sour is stimulated by any acids present in food The receptors for this are on the side of the tongue tip of the tongue Sweet is stimulated by organic salts such as sugar and salt The receptors for this are on the Bitter is stimulated by alkaloids so the opposite pH or the sour taste This is like caffeine and nicotine The receptors for this are on the back of the tongue Salty is by inorganic salts The receptors for this are on the side of the tongue Umami is by certain AA s like glutamate Receptors are mostly in the pharynx o Any other flavor we taste is a certain combination of these 5 tastes I just remember that sweet always comes first followed by sour and salty tastes Then no one like bitter so it is in the back of the tongue Then no one care or knows what umami tastes like so it is in the throat This is how I learned where the receptors are 6 Describe the physiology and transduction of gustation including the afferent fibers that are involved First the chemical will dissolve in your saliva and then the chemical will bind to a gustatory cell hair and this will induce depolarization causing an AP This AP will cause a 21 neurotransmitter to be released Depending on the type of taste the chemical is it will cause the depolarization in a different way Salty tastes will cause sodium to enter the cell sour tastes will block potassium channels so potassium can t leave thus making the cell positive and the other tastes will undergo the G protein cascade to cause calcium to enter So regardless of the taste depolarization will occur but know how it occurs The NT will then bind to a first order neuron and this is one of the cranial nerves either the glossopharyngeal nerve on the
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