ELM 15 Hearing, chemical senses and touch Flashcards
How does smell perception vary across species?
Smell perception is similar across species, with neurons converging based on their response to specific odorants, often at glomeruli.
What is the role of glomeruli in the olfactory system?
Glomeruli play a role in olfaction by serving as sites where neurons with similar odorant responses converge.
Describe the signaling pathway involved in human olfactory receptors.
Human olfactory receptors are G-protein coupled receptors (GPCRs) that, upon odorant binding, trigger the opening of cyclic nucleotide-gated channels and depolarization of olfactory receptor neurons.
How does odorant binding affect the membrane potential of olfactory receptor neurons?
Odorant binding leads to depolarization of olfactory receptor neurons, unlike in vision where light causes hyperpolarization.
What is combinatorial coding in the olfactory system?
Combinatorial coding in olfaction refers to the diverse chemical structures of odorants and the unpredictable nature of smell based on structure. Each odorant binds to various receptors, activating many neurons, and each neuron can be activated by multiple odorants.
What makes predicting the smell of a substance challenging based on its chemical structure?
The diverse chemical structure of odorants makes predicting smell based on structure challenging, as different odorants can activate the same receptors and vice versa.
How does olfaction differ from vision in terms of neural processing?
Unlike vision, where light passes through retinal cell types before activating photoreceptors, olfaction involves direct synaptic interaction between odorants and GPCRs.
What is the primary difference in the origin and direction of the stimulus between olfaction and vision?
The primary difference between olfaction and vision lies in the origin and direction of the stimulus: in olfaction, the stimulus is an odorant that directly synapses with GPCRs, while in vision, light stimuli come from the bottom up, passing through retinal cell types before reaching photoreceptors.
Explain the direct synaptic interaction between odorants and receptors in olfaction.
n olfaction, odorants directly synapse with GPCRs on olfactory receptor neurons, triggering a cascade of events leading to neural activation.
Contrast the pathway of stimulus in olfaction with that in vision.
Olfaction involves direct synaptic interaction between odorants and receptors, while vision requires light to pass through all retinal cell types before activating photoreceptors.
What are the five tastes crucial for survival, and what are their functions?
he five tastes essential for survival are bitter (to avoid poisons), sweet (indicating sugar/carbs), umami (associated with amino acids), salty (related to Na+), and sour (signifying acids/H+).
What is the suggested potential sixth taste based on evidence, and what does it relate to?
vidence suggests a potential sixth taste related to fat, based on the presence of fat receptors in the tongue.
define taste receptor cells (TRCs), and what is their regenerative capability?
Taste receptor cells (TRCs) are neuroepithelial cells capable of regeneration. They form taste buds and play a role in taste perception.
Explain the composition and function of taste buds.
Taste buds contain cells that detect tastants and release neurotransmitters when activated, which then activate gustatory nerves.
What are the three main structures of taste buds/papillae?
Taste buds are found in three main structures: circumvallate, foliate, and fungiform papillae.
Where are taste/gustatory receptors primarily found in humans, and how does this compare to Drosophila?
In humans, taste/gustatory receptors are primarily located on the tongue, while in Drosophila, similar receptors are found in various locations such as legs and wings, serving different functions.
How do gustatory neurons in Drosophila differ in distribution and function from those in humans?
Gustatory neurons in Drosophila are not specific to the tongue and are found in various places, unlike in humans where they are primarily on the tongue and dedicated to taste perception.
What are the molecular mechanisms underlying gustatory receptor function?
Gustatory receptors utilize diverse molecular mechanisms. Some are G-protein coupled receptors (GPCRs), while others involve transient receptor potential (TRP) channels and epithelial sodium channels.
Which taste receptors are currently best understood in terms of their molecular structure and signaling pathways?
The molecular structure and signaling pathways of bitter, sweet, and umami taste receptors, which are GPCRs, are currently best understood.
Which receptors are involved in detecting sour and sodium tastes?
Sour taste is detected by TRP channels, while sodium taste involves epithelial sodium channels, though the latter are not present in humans.
What is the vomeronasal organ (VNO), and where is it located?
The vomeronasal organ (VNO) is an additional olfactory organ located in the nasal cavity, above the roof of the mouth.
What types of chemical cues does the vomeronasal organ respond to?
The VNO responds to non-volatile chemical cues in the environment.
How do snakes use tongue flicking behavior in relation to the VNO?
Snakes exhibit tongue flicking behavior to sample scents from the environment and deliver them to the VNO.
How do elephants utilize their trunk and behavior to deliver scents to the VNO?
Elephants use their trunk, often with a prehensile “finger” at the tip, to deliver scents to the VNO. They can also direct inhaled air onto it.
