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
distinguish between the two different types of pathways that touch information can take in the spinal cord - what kind of touch info goes to each & the speed of each
1) Spinothalamic pathway: evoluntionarily older, carries info from thermoreceptors and nociceptors, slower
2) DCML: carries info that is tactile and kinesthetic, quicker (action-oriented receptors - need to constantly update so you can move around/interact with the world)
What’s the 2 point threshold?
- What’s important to remember about it?
the minimum distance at which 2 stimuli feel like 2 different stimuli
- different parts of our bodies have different levels of sensitivity
Where are we most sensitive to the two-point threshold?
in extremities (hands, feet)
The areas that are more sensitive to the 2-point threshold correspond to what? Why?
larger areas of cortex
- because areas w/ larger area of cortex correspond to areas on the body with a higher concentration of tactile receptors
What type of receptors does the 2-point threshold deal with?
mechanoreceptors (pressure/ skin displacement)
In what two ways do the structures of the middle ear modulate sound?
- The joints between the 3 little bones in the ears work like levers: a small amount of energy on one side of the joint becomes larger on the other side of the joint - amplifies the sound
- Concentrate energy from a larger to a smaller surface area. Tympanic membrane is 18x as big as the oval window. The amount of force acting is the same on the OW as it was on the TM, but with a smaller amount of surface area, this results in an increase in amplitude of the sound by about 18x by the time it reaches the OW.
two main pathways that make up the auditory system
- explain each
- Afferent (ascending) - fibers in the auditory nerve that take info from ear to brain
- Efferent (descending): fibers in the auditory nerve that take info from brain to ear
- e.g./ when you’re listening for something - what is that?
the two pathways of the auditory system are associated with what? Explain
a certain type of hair cell
- Afferent - inner hair cells
- Efferent - outer hair cells
what happens when efferent fibers of the AN become active?
they signal outer hair fibers to become longer, which makes the cochlear partition stiffer - ear is not as sensitive to sound
what is a complex tone?
a sound wave made up of more than one sine waves of different frequencies
what is a fourier analysis?
a way of breaking down complex tones into their component sine waves
what does a spectrum show?
the intensity of each sine wave
what is a harmonic spectrum?
each frequency component in such a sound is called what?
the spectrum of a complex sound in which energy is at integer multiples of the fundamental frequency
- a harmonic
define timber
- explain more in-depth
- give ex/
- quality of sound: the fact that each sound has a different spectral appearance, even if they are producing the same frequency
- what allows a listener to judge that two sounds of the same loudness and pitch are dissimilar
ex/ what allows you to distinguish a guitar from a piano
what is the pinna?
the part of the outer ear you can see
what is the ear canal?
- functions?
- tunnel that leads sound to your ear drum
- protects tympanic membrane
- enhances sound frequencies
what is the tympanic membrane? (2)
- border betwen inner and middle ear
- thin sheet of skin that moves in response to sound pressure changes
what is the middle ear made up of? give the order
ossicles - smallest bones in the body
- TM (border), malleus, incus, stapes, OW (border)
muslces in the middle ear that control the ossicles
tensor tympani and stapedius
what muscles are responsible for the acoustic reflex? what is the acoustic reflex?
- tensor tympani & stapedius
- these muslces tense when sounds are loud to keep the pressure from loud noises from damaging the inner ear
main structure of the inner ear?
the cochlea
the inner ear is made up of _______, all filled with ______ and separated by ________
3 parallel canals, fluid, 2 membranes
what is the cochlear partition made up of in order? what happens in the cochlear partition?
1) tectorial membrane (on top)
2_ organ of corti
3) basiliar membrane (on bottom)
- sound waves are turned into neural signals
What contains the hair cells?
organ of corti
what are stereocilia? differences?
tine fiber bristles on the end of hair cells, little nerve fibers
outer = v-shaped
inner = short to tall arrangement
tectorial membrane location? (2)
- how does it move?
- what is this called?
- runs along the top of the organ of corti
- is attached to OUTER hair cells (tallest steriocilia of outer hair cells attach to it)
- when the cochlear partition moves as the result of sound pressure, the tectorial membrane moves OPPOSITE the hair cells
- this is called shear
steriocilia are connected by what? what does this cause?
tiny filaments called tip links
- when the tectorial membrane moves, it pushes on the tallest steriocilium in the string, opening K channels
give the book definition of place code theory?
- the amplitude of a sound wave causes bending of the hair cells at a SPECIFIC location along the basiliar membrane/organ of corti
- the PLACE where the stimulation occurs determines what we hear
explain the place code theory simpler
- where are specific frequencies on the cochlea?
the cochela is mapped according to space = tonotopic mapping
- different frequency/amplitude combinations elicit reactions at different parts of the cochlea
- where on the cochlea stimulation occurs determines what we hear
- ** high frequencies = base, low frequencies = apex
