Week 9- Taste & Smell Flashcards Preview

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Flashcards in Week 9- Taste & Smell Deck (31)
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1
Q

What are chemoreceptors?

A

receptors that sense a change in ion concentration (increasing acidity)

2
Q

What are some chemoreceptors in the body?

A

Cutaneous nociceptors (chemicals on skin)

Lactic acid sensors in skeletal muscle

Gut enterocutes

Olfactory receptors (olfaction)

Taste busts (gustation)

3
Q

Where are taste bud found?

A

Found primarily on the upper surface of the tongue

4
Q

What makes a taste bud?

A

50 longe, spindle-shaped taste receptor cells together with supporting cells. Each has a taste pore

5
Q

What is the function of the lingual papillae?

A

to increase surface area and friction

6
Q

Name the 4 types of lingual papillae

A
  • Filiform papilla
  • Fungiform pailla
  • Circumvallate papilla
  • foliate pailla
7
Q

Describe the filiform papilla

A
  • Most numerous
  • do not contain tastebuds
  • provide friction and grip
  • gives tongue fury feel
8
Q

Describe fungiform papilla

A
  • Contain 5 taste buds at the surface
  • found on dorsal aspect of tongue
  • Sweet, sour, bitter, umami
  • VIIth CN innervation
9
Q

Circumvallate pailla, explain

A
  • Dome shaped
  • 8-12 in total
  • contain 100 taste buds each
  • glossopharyngeal innervation
  • sensitive to bitter taste
10
Q

Foliate papilla, explain

A
  • within folds at the side of tongue
  • many taste buds
  • IX Cn innervation
11
Q

Describe the life span of a taste bud

A

10-14 days
can be damaged by heat
- Surrounding epithelial cells differentiate into supporting cells (basal), then into receptor cells

12
Q

Describe taste receptor cells

A
  • microvilli protrude slightly through the pore
  • only stimulated by dissolved chemicals
  • binding alters the cells ionic channels and depolarises cell- receptor potential
  • RP initiates ATP or serotonin release, causing AP on primary gustatory neuron
13
Q

How does taste discrimination occur?

A

5 tastant receptors: Salty, sour, sweet, bitter, umami (and potentially starchy)

  • different transduction channels for each tastant
  • receptor cells respond to all, but are dominated by 1
14
Q

What are the different types of presynaptic cells?

A

Type 1: support cells
Type 3: depolarisation–> serotonin release
Type 2: G-protein coupled receptors resulting in ATP release
Type 4: basal cells

15
Q

What evokes bitter, sweet and umami taste?

A

Bitter: chemically diverse group of tastants, 50-100 receptors, each responding to a different bitter flavour

Sweet: glucose

Umami: amino acids

16
Q

What CNs synapse with taste buds in the mouth?

A

VII, IX, X

17
Q

Where do the nerves coming from the taste buds synapse

A

Gustatory cortex, via the brainstem and thalamus

18
Q

Where does the desire for taste originate?

A

Limbic system, adding affective dimensions to percept, along with the hypothalamus

19
Q

What other information influences taste perception?

A
  • Olfaction
  • temperature
  • texture
  • psychological factors
20
Q

What is the specific hunger phenomenon?

A

Craving a substance lacking in the body, i.e. lack salt appetite due to lack of Na in the body

21
Q

Where are olfactory chemoreceptors located?

A

In the olfactory mucosa at the roof of the nasal cavity

- olfactory receptors, supporting cells and basal cells

22
Q

What are basal cells precursors for and how often does this change occur?

A

Basal cells are precursors for olfactory receptor cells, being replaced every 2 months

23
Q

Describe the appearance of olfactory receptor cells

A

Enlarged distal end with several long cilia extending to the surface of the mucosa

24
Q

What do the cilia of olfactory receptor cells contain?

A

Odorant binding sites

  • enter both naris
  • must be volatile and water soluble
25
Q

Where do axons of the olfactory receptors form?

A

The olfactory nerve (CN I)

26
Q

Where do olfactory receptors synapse?

A

With peripheral dendrites of mitral cells in glomeruli, mitral neurons transmitting to the brainstem

27
Q

How do glomeruli play a role in scent perception?

A

Glomeruli only receive inputs from olfactory cells with the same odorant sensitivity

28
Q

How is olfactory stimulus detected?

A

By multiple olfactory receptors.

  • Humans have more than 1000 different receptor types
  • 1 odor molecule results in a unique receptor activation pattern, stimulating a unique glomeruli pattern
29
Q

Describe the central olfactory pathways

A
  1. Subcortical route–> diffuse projections to limbic system –> primary olfactory cortex–> hypothalamic input, allowing close coordination between feeding, mating and direction orientation
  2. Route through the thalamus to the orbitofrontal cortex–> conscious perception and discrimination of smell
30
Q

How are smell and emotion linked?

A

The subcortical route involves the amygdala, hippocampus and parts of the limbic system involved with emption and memory. Smell can also induce a strong sense of nostalgia.

31
Q

What is the Vomeronasal organ?

A

Detects pheromones, stimulating subconscious change in emotion and socio-sexual behaviour