Brainscape's Knowledge GenomeTM

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


See full index

PHSL231 > Lecture 24- Taste > Flashcards

Lecture 24- Taste Flashcards

1
Q

What two senses are known as the chemical senses? What are their purpose?

A
  • Taste (gustation)
  • Smell (olfaction)

Vital from an evolutionary standpoint so that we avoid eating things that could be poisonous (usually taste bitter/ rancid). Also play a role in finding a compatible mate so can pass on genes.

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

What cells are responsible for detecting the stimulants (chemicals) in taste and smell?

A

Chemoreceptors

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

What are the bumps on the tongue called? What are the two large bumps at the back? And at the sides?

A
  • Papilla
  • At back= vallate papilla
  • At sides= Foliate papilla
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What sits underneath the papilla (folds of epithelium)?

A

Taste pores, taste hairs then taste buds

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

What structure is responsible for the sensation of taste?

A

Taste buds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 5 tastes? What are they stimulated by?

A
  • Sweet: stimulated by sugars
  • Sour: stimulated by acids
  • Salty: stimulated by sodium (NaCl)
  • Bitter: complex, but typically stimulated by alkaloids
  • Umami: stimulated by amino acids, especially glutamate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Is it true that different parts of the tongue are sensitive to different tastes?

A

Yes but it is not as distinct as the taste maps you were shown in primary school

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How many taste buds do we have and where?

A

2000-5000 taste buds, on tongue, palate, pharynx and epiglottis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do taste buds consist of?

A

Compact cluster of 50/100 columnar epithelial cells (type I, type II and type III)

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

Which of the types of cells that make up taste buds are the tasting cells and which are the support/ glial cells?

A
  • Type 1= support/ glial

- Type 2 + 3= taste cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the general cell signal transduction mechanism?

A
  1. Interaction of tastant with receptor causes increase in intracellular Ca2+
  2. Ca2+ flux causes release of neurotransmitter or signaling molecule which interacts with afferent nerve fibre
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Is there just one neurotransmitter invovled in the sensation of taste?

A

No, there are many…

ATP, GABA, serotonin and Ach are transmitters/ signaling molecules involved in taste signaling in taste buds

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

Humans can detect 5 different tastes BECAUSE Humans have 5 types of taste cell

A – Both answers are correct and causally related
B – Both answers are correct but not causally related
C – First statement is true but second is false
D – First statement is false but second is true
E- Both statements are false

A

C- first statement is true but second is false

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What three tastes are related in that they all involve G-protein mediated signaling in type 2 taste cells?

A
  • Bitter
  • Umami
  • Sweet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the pathway for sweet….

A
  • Tastant interacts with a homodimer of the type 1 receptor
  • Activation of G-protein coupled receptor –> Activation of Phospholipase C
  • Opening of IP3R3 channel and calcium efflux into cytoplasm
  • Opening of TRPM5 channel leads to sodium influx leads to taste cell depolarization
  • Opening of CALHM1 channel leads to ATP release leads to depolarization of afferent nerve fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the pathway for bitter…

A
  • Tastant interacts with a monomer of the type 2 receptor
  • Activation of G-protein coupled receptor –> Activation of Phospholipase C
  • Opening of IP3R3 channel and calcium efflux into cytoplasm
  • Opening of TRPM5 channel leads to sodium influx leads to taste cell depolarization
  • Opening of CALHM1 channel leads to ATP release leads to depolarization of afferent nerve fibres
17
Q

Describe the pathway for umami…

A
  • Tastant interacts with a heterodimer of the type 1 receptor
  • Activation of G-protein coupled receptor –> Activation of Phospholipase C
  • Opening of IP3R3 channel and calcium efflux into cytoplasm
  • Opening of TRPM5 channel leads to sodium influx leads to taste cell depolarization
  • Opening of CALHM1 channel leads to ATP release leads to depolarization of afferent nerve fibres
18
Q

How does non G-protein signaling in type 3 cells work for sour tastants?

A
  • Stimulated by acids (such as acetic acid or citric acid)
  • Protons enter the cell via a proton-selective channel (Otop1) which decreases pH and blocks leaky K+ channels (positive charge cannot leave)
  • Cell depolarizes (Na+ coming in) resulting in the release of neurotransmitter onto terminal of afferent nerve fiber + action potentials
19
Q

How does non G-protein signaling in type 3 cells work for salty tastants?

A
  • NaCl, and Na+ containing compounds
  • Probably sensed by type III taste cells
  • Na+ likely enters through ENaC (epithelial Na+ channel)
  • Depolarisation results in release of neurotransmitter onto afferent nerve fibres

This one is still controversial (not a lot is known!)

20
Q

What is the central signal transduction pathway?

A
  • Taste buds innervated by chorda tympani, lingual, trigeminal and glossopharyngeal nerves (lots of different types of nerves!)
  • Afferent fibres synapse in the medulla
  • Info relayed to the thalamus, then to the cortex
21
Q

What is the motor supply for the tongue muscles called?

A

Hypoglossal

22
Q

Are spicy or peppery (pungent) foods considered tastes?

A
  • No as they do not interact with specific taste receptors
  • They are instead sensed by heat and pain-sensitive nerve fibers stimulated by chemical such as capsaicin (chilis) and piperine (peppers).
23
Q

What are astringent foods? Why do we ‘taste’ them but they are not considered one of the actual tastes?

A
  • High amount of tannins e.g. Popcorn, unripened bananas, pomegranates
  • causes mucus layers in mouth to contract, leaving your mouth dry
24
Q

Why are fatty foods hypothesized as the ‘sixth’ taste?

A

-They may interact with the specific receptor CD36 and then follow a similar process as sweet, bitter and umami aside from the fact that no-one knows whether it is G proteins coupled to activate phospholipase C or something else occurs

25
Q

Is just one receptor/ taste activated when we eat foods? What is taste also often linked to?

A

No- a number to get the overall profile.

Also often linked to our perception of smell

26
Q

What is Aguesia?

A

The total loss of taste

27
Q

What is Dysguesia?

A

Persistent horrible taste in the mouth

28
Q

What is Hypoguesia? What can be the causes?

A

-Partial loss of one type of taste

May happen due to:

  • Neurological damage: Stroke
  • Smoking: Change in form, quantity and vascularization of taste buds
  • Infection
29
Q

A reduction in intracellular pH depolarises Type II taste cells BECAUSE leaky K+ channels are blocked when pH reduces

A – Both answers are correct and causally related
B – Both answers are correct but not causally related
C – First statement is true but second is false
D – First statement is false but second is true
E- Both statements are false

A

D- First statement is false, second is true

PHSL231 (28 decks)

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