olfaction Flashcards

chapter 14

1
Q

odor

A

any smell sensation

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2
Q

odorant

A

a chemical compound that we can smell
- it must be volatile, small and hydrophobic

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3
Q

nose function

A
  1. filter and hummidify air
  2. smell
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4
Q

olfactory cleft

A

part at the back of the nose where the main olfactory epithelium is located

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5
Q

olfactory epithelium

A

patch of tissue in the upper nose that contains ORNs and is covered in a layer of mucus

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6
Q

cribiform plate

A

a bony tructure riddled with tiny holes that separates the nose from the brain
- axons of the ORNs pass through it

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7
Q

anosmia

A

the total inability to smell often resulting from illness or head injuries
- loss of taste

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8
Q

supporting cells

A

metabolic and physcial support to the olfactory receptors

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8
Q

cells in the olfactory epithelium

A
  1. supporting cells
  2. basal cells
  3. olfactory receptor neurons
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8
Q

basal cells

A

precursor cells to olfactory receptor neurons
- help replace them when they die

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9
Q

olfactory receptor neurons

A

the main cell type that contains receptors on its ilia
- located under the watery mucous layer

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10
Q

olfactory bulb

A

bulbous end of the olfactory tract containing mitral, tufted and glomeruli cells

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11
Q

mitral cells

A

the main projective output neurons in the olfactory bulbs
- relay

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12
Q

tufted cells

A

sencodary output neurons in the olfactory bulbs
- their axons form the olfactory tract which go to the brain

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13
Q

glomeruli

A

spherical conglomerates containing the incoming axons of the ORNS
- each receptor cells converge onto two glomureli and then synapse onto the mitral and tufted cells

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14
Q

cilia

A

hair like prootrusions on the dendrites of ORNs that contain receptors for oderants

15
Q

olfactory receptors

A

region on the cilia that oderant molecules bind to

16
Q

ORN adaptation

A

the nose adapts to oderants so if ypu give a burst then another immediately after, they will respond less to the second one
- if you wait 5 seconds it will be recovered
- cortical adaptations happens too

17
Q

psuedogenes

A

we have about 1000 different genes but about 60-70% dont work.
- so we have about 300-400 receptors

18
Q

neural coding for odors

A

the receptors each bind to one specific molecule but they work together in a population code to to account for the whole variety of smells we perceive

19
Q

piriform cortex

A

the primary olfactory cortex which receives signals directly from the olfactory bulb
- dedicated solely to olfaction

20
Q

entorhinal cortex

A

receives direct input from olfactory regions and provides the major association input into the hippocampus

21
Q

amygdala-hippocampus complex

A

critical for the unique emotional associative properties of olfactory cognition

22
Q

limbic system

A

the encompassing group of neural structures that include the olfactory cortex, amygdala, hippocampus, piriform cortex and entorhinal cortex
- olfaction is very connected to this system which gives it unique emotional associations

23
tip of the nose phenomenon
- when you know a smell but cat name it - olfaxtion is disconnected from language and does not fo through the thalamus so it does not integrate with the other senses
24
cross adaptation of smell
the reduction in detection of an oderant following exposure to another oderant
25
cognitive habituation
psychologucal process by which, after a long term exposure to an odorant, one is no longer able to detect that odorant or has very diminished ability
26
why do we have cognitive habituation of smell
1. receptors may be hindered after continuous exposure and may take longer to recycle 2. odorant molecules may be absorbed into bloodstream 3. cognitive-emotional factors
27
attention and smell
we need some level of attention to smell - looking for smell helps us detect it