Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology 2 > Neuro: The Chemical Senses > Flashcards

Neuro: The Chemical Senses Flashcards

1
Q

What are some of the chemical senses that our bodies are able to detect?

A
  • Taste (gustation)
  • Smell (olfaction)
  • CO2/O2 levels
  • Chemical irritants
  • Acidity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are we able to detect CO2/O2 levels?

A

Chemoreceptors in arteries of neck detect levels of CO2/O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are we able to detect chemical irritants?

A

Nerve endings in skin/muscous membranes detect chemical irritants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are we able to detect Acidity?

A

Sensory nerve endings in muscle are able to detect/respond to acidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What flavours do humans have an innate preference/dislike for? Why is this?

A
  • Humans innately enjoy sweet flavours and innately dislike bitter flavours
  • Allowed humans to distinguish between food sources
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Can experience modify our innate taste preferences?

A
  • Yes, this is why most people go on to enjoy bitter taste of coffee
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 5 basic tatses?

A
  • Sweet
  • Sour
  • Bitter
  • Salt
  • Umami
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do we perceive the flavour of food?

A

Perception of flavour a combination of different factors:

  • Particular combination of the 5 basic tastes within the food
  • Smell of food
  • Texture/temperature of food
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the primary organ of taste?

A

Tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the other organs of taste and how do they contribute to it?

A
  • Palate (roof of mouth) - taste buds present in palate
  • Epiglottis - taste buds present in epiglottis
  • Pharynx and nasal cavity - Odours can pass into nasal cavity, via pharynx, where it gets detected by olfactory receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

On the tongue what are different types of papillae?

A
  • Fungiform papillae - mushroom shaped
  • Foliate papillae - ridge shaped
  • Vallate papillae - pimple shaped
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where exactly are the taste buds located on the tongue?

A

Taste buds are located within the ridges formed between the papillae of the tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the structure of a taste bud

A
  • Taste pore - chemically sensitive end of taste bud
  • Microvilli project from taste pore which surrond gustatory afferent axons (send signals to brain)
  • Between microvilli of taste pore there are taste cells which synapse with the gustatory afferent axons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What structure within the taste cells mean they are able to respond to taste?

A
  • Taste cell receptors
  • Each taste cell expresses different taste receptors - most taste cells respond primarily or exclusively to one of the five basic tastes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What taste transduction mechanisms are ion channel mechanisms?

A
  • Saltiness
  • Sourness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain the saltiness taste transduction mechanism

A
  • Na+ passes through Na+ selective channels down its concentration gradient
  • This Na+ influx causes depolarisation which activates Voltage-gated Ca2+ channels leading to Ca2+ influx
  • This leads to release of neurotransmitters from vesicles via exocytosis
  • Neurotransmitter release leads to activation of gustatory afferent axons which send signals to brain
17
Q

What is the specific name of the Na+ selective channels within particular taste cells? What are some of the properties of this channel

A
  • Amiloride-sensitive Na+ channel
  • Can detect low salt concentrations
  • Insensitive to voltage so always stay open
18
Q

Explain the sourness taste transduction mechanism

A
  • H+ passes down (Amiloride-sensitive) Na+ selective channels down its concentration gradient
  • H+ binds and blocks K+ selective channels so more K+ remains in the cell
  • More H+ and K+ within the cell leads to depolarisation which activates the voltage-gated Ca2+ channels
  • This leads to Ca2+ influx which results in neurotransmitter release from vesicles via exocytosis
  • Neurotransmitters bind and activate gustatory afferent axons which send signals to brain
19
Q

What taste transduction mechanisms are controlled by G-protein couplled receptor mechanisms?

A
  • Sweetness
  • Bitterness
  • Umami
20
Q

Sweet, bitter and Umami taste receptors all form dimers and are all G-protein coupled receptors. What combination of taste receptor protein make up each type of receptor?

A
  • Bitter receptors - 2 T2Rs
  • Sweet receptor - T1R2 and T1R3
  • Umami receptor - T1R1 and T1R3
21
Q

Explain the bitterness taste tranduction mechanism

A
  • Bitter tastant binds to T2R, couplled to Gq protein, causing it to activate
  • Activated T2R cativates phospholipase C enzyme which converts PIP2 into IP3 and DAG
  • IP3 binds to a special Na+ ion channel causing influx of Na+
  • IP3 also binds to receptors on endoplasmic reticulum causing it to release Ca2+ into cytosol
  • These 2 effects cause depolarisation which causes the release of ATP
  • ATP activates gustatory afferent axons which send signals to brain
22
Q

Explain the sweetness taste transduction mechanism

A
  • Sweet tastants bind to dimer receptor formed from T1R2 and T1R3
  • Mechanism is the same as the bitterness taste transduction mechanism
23
Q

If the sweet and bitter taste transduction mechansims are the same why does the brain not get them confused?

A
  • Taste cells express either bitter or sweet receptors NOT both
  • Also, bitter and sweet receptors activate different gustatory afferent axons
24
Q

Explain the umami tatse transduction mechanism

A
  • Umami tastants bind to dimer receptor formed from T1R1 and T1R3
  • Transduction mechanism same as bitter and sweet mechanisms
25
Q

Why does the brain not confuse Umami, sweet and bitter tastes if all the transduction mechanisms are the same?

A
  • Taste cells only express either Umami, sweet or bitter taste receptors
  • Each taste receptor also activates different gustatory afferent axons
26
Q

Explain how information from the taste buds gets to the CNS via the central gustatory pathways

A
  • Taste buds on anterior tongue connect with cranial nerve 7 (CN VII)
  • Taste buds on posterior tongue connect with cranial nerve 9 (CN 9)
  • Taste buds on epiglottis connect with cranial nerve 10 (CN X)
  • Each of these cranial nerves project to the gustatory nucleus (in the medulla)
  • Gustatory nucleus sends message to the ventral posterior medial nucleus (in the thalamus)
  • Ventral posterior medial nucleus sends a signal to the Gustatory cortex
27
Q

Are some of our smell preferences innate? Can experinece modify these innate preferences

A

Yes some of our smell preferences are innate but experineces can modify our innate preferences

28
Q

What is the main organ of smell?

A

Olfactory epithelium - we DO NOT smell with our noses

29
Q

Describe the structure of the olfactory epithelium

A

Olfactory epitheleium contains:

  • Olfactory receptor cells - site of transduction (actual neurons)
  • Supporting cells - function like glia cells and produce mucus
  • Basal cells - immature olfactory receptor cells (source of new olfactory receptor cells)
30
Q

Explain the olfactory transduction mechanism

A
  • Odorant molecules bind to olfactory receptor proteins on cilia
  • This causes Olfactory-specific G protein (Golf) to become activated
  • Activated Golf activates adenylate cylase which forms cAMP from ATP
  • cAMP causes cAMP-actiavted channels to open which causes Na+ and Ca2+ influx
  • Ca2+ opens Ca2+ activated Cl- channels leading to Cl- efflux
  • This leads to membrane depolarisation
31
Q

Describe the pathway an action potential would take through an olfactory receptor cell/neuron

A
  • Odorants bind to receptors on cilia which generates a slow receptor potential
  • Receptor potential then propagates along dendrites and triggers series of action potentials within olfactory cell stroma
  • Action potential propagates continously along olfactory nerve axon
32
Q

Where do the olfactory receptor cell axons project to?

A
  • Olfactory receptor cell axons project to the olfactory bulb
  • The olfactory bulb contains structures called Glomeruli
  • Olfactory receptor cells expressing the same receptor proteins project to the same Glomerulus within the olfactory bulb
33
Q

Explain how information from the olfactory receptor cells gets to the CNS via the central olfactory pathways

A
  • Olfactory receptor cells connect to cranial nerve 1
  • Cranial nerve 1 projects to the olfactory bulb
  • Olfactory bulb then sends signals to different brain areas to process different aspects of smell:
  • It sends signals to Frontal cortex - processes conscious perception of smell
  • It sends signals to hypothalamus and amygdala - processes motivational and emotional aspects of smell
  • It sends signals to the hippocampus - processes odour memory
34
Q

What is population coding?

A

Occurs when the responses of a large number of broadly tuned neurons are used to specifiy the properties of a particular stimulus e.g. taste or smell

35
Q

Give an example of population coding based on olfaction

A
  • When presented with a citrus smell, none of the three receptor cells can individually distinguish it from the other odours.
  • However, the brain can distinguish the citrus smell through the combination of responses from all three olfactory receptor cells.

Physiology 2 (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions