Final Exam Flashcards
What is a chemical sense? Explain simpler
- What are the chemical senses?
- senses that take in tiny particles from the air and use the chemical info from that particle to transduce a neural signal
- there’s actually a chemical reaction between the particle and your sensory system - the substance actually enters your body
- olfaction and gustation
What’s significant about the chemical senses?
- what is their important evolutionary function? usually has to do with?
- Give ex/’s
- they were the earliest senses to evolve
- they tell us when to approach or withdraw
- a food source
- Ex/ smells/tastes bad = automatically want to get away from it
- Ex/ toxic smells/smoke = want to withdraw
- Ex/ flowers/yummy foods/loved ones = want to approach
What is an odor?
give ex/
the experience - a general smell sensation of a particular quality
ex/ the cake had a chocolate odor
what is an odorant?
give ex/
the specific chemical makeup of the substance
ex/ you were given the odorant methol to smell
what is the olfactory cleft?
uppor part of the back of the nose where air flows and where the olfactory epithelium are located
what is the olfactory epithelium?
- the film of mucus that covers the olfactory cleft
- like the retina of the eyes - where odorants are converted into neural impulses
what are olfactory sensory neurons?
- Describe the structure, other structures related
the cells in the olfactory epithelium
- their dendrites poke out through the olfactory epithelium (called CILIA)
- on the very top of cilia = OLFACTORY RECEPTORS
- When chemicals from molecules make contact with ORS, they begin an AP
Why do some smells have a “feel”? e.g feel cook, feel like their burning your nose, feel painful
- because of trigeminal nerve - signals of olfactory nerve and trigeminal nerve get combined, input to brain in similar place as smell
what is meant by the “mind’s nose?”
our ability to reconstruct our olfactory perceptions in our imagination
what’s impt to remember about the mind’s nose?
we might have it, but it’s less strong than our mind’s eye
research that suggests that our mind’s nose isn’t as strong as our mind’s eye (3)
- fMRI scans show much less overlap for real and imagined smells
- we don’t typically dream in smell
- we don’t typically think in smell
why do we consider smell the mute sense?
- aka what? Explain
we have a harder time attaching a verbal label to smell than we do in any other sense
- tip of the nose phenomenon: happens more with smell than with any other sense (you recognize a smell and you can’t bring a verbal label to mind)
- AND it’s harder to resolve (we have fewer tricks to resolve it - e.g. go through letters of alphabet, etc)
There seems to be a disconnect between smell and _____? Explain
- Why???
language - across all languages, there are fewer smell words than any other sense
- not routed through thalamus (only sense that isn’t)
- competition of neural resources between language and smell (no other animals smell - maybe long ago language/speech parts of brain were used for smell)
describe the difference between taste and flavor
taste - chemical reaction that occurs on surface of tongue; when molecules from our food are dissolved in our saliva and pass over the taste receptor cells on our tongue and a signal is sent to the brain
flavor - overall sensation of goodness/badness; a combination of taste and some of the molecules getting sucked up into nasal cavity
- also includes thing like texture, temperature, etc.
How do we sort of have 2 smell senses?
Why doesn’t this really make sense?
- Orthonasal - involved in smell; particles come in through the nose
- Retronasal - enter nasal cavity through back part of mouth rather than nostrils but still end up in olfactory epithelium; involved in taste
* **our brains don’t separate out the retronasal smell from taste, so we perceive it as one thing
* **different parts of brain are activated for each type of smell
- cuz they activate same receptor sites, but we somehow know which smells come from air and which come from mouth
- why you can smell something and then eat it ant it tastes different than what it smelled like
Describe the spatial layout of the taste receptors for bitter, sour, salty, and sweet tastes across the tongue. Do we have zones specifically for each of these tastes?
- we DON’T have zones for each of these tastes
- there ARE 4 different types of papillae that are located in different regions of the tongue, and there ARE different types of receptors that perceive different types of tastes
- BUT these different types of receptors are distributed evenly across the whole tongue - different flavors don’t match up with different type of papillae or anything like that
How are the pathways of the sensory nerves to the brain organized differently in touch compared to other senses? (2)
- There are only 2 opitc nerves and 2 auditory nerves - There are MANY somatosensory nerve trunks
- Axons in optic and auditory nerves go directly to brain, while axons for touch synapse at the SPINAL CORD first
one major one skin receptor cells are different from photoreceptors and hair cells?
touch info has to travel WAY further than vision and sound info
once touch info is in the spinal cord, what happens?
it’s directed through two pathways depending on the type of touch info
1) spinothalamic pathway
2) Dorsal Column-Medial Lemniscal Pathway (DCML)
- Both of these pathways end up in the THALAMUS
- Then, most touch info goes to the primary and secondary SOMATOSENSORY areas
