Principles of Neuroscience Lecture 10, Gustation & Olfaction Flashcards
What is flavour?
Flavour is the sensory experience of food and drink
What is the different between olfaction and taste?
How do they inter-relate?
Olfaction: volatile chemicals entering nose and landing on olfactory receptor cells
Gustation: chemicals taken into mouth and eliciting response in taste cells
There are separate centres in the brain that deal with each.
Flavour sensation is a combination of both taste and smell.
What factors influence flavour perception?
Taste Smell Appearance Temperature Texture Chilli Fat
What is the epiglottis?
Flap of cartilage over the trachea, preventing food entering during swallowing
Outline the different taste regions of the tongue.
Sweet
Salty
Sour
Bitter
Why are humans adapted to taste these 5 flavour groups and not others?
These flavours are important because the compound are energy rich (sugar), required for bodily functions (salt), indicate food going bad (sour, acid) or toxicity (bitterness)
Describe the sensory structures in the tongue
The tongue has papillae which are visible to the naked eye, and contain many taste cells.
Taste cells are the sensory cells of the gustatory system.
How many taste cells does a normal tongue have?
2000-5000
Can taste cells be replaced?
Yes, they are turned over every two weeks
Do individual taste cells is a papillae detect the same chemicals, or different ones?
Taste cells within a single taste bud have different sensitivities.
However, the final output from a taste cell is integrated centrally so as to create the regional sensitivities of the tongue.
Describe the generalised process of gustatory transduction
Chemicals from food enter the taste pore and interact with receptors on the taste cell.
Depolarisation of the taste cell due to transduction
Fusion of vesicles containing neurotransmitters onto the gustatory afferents
Describe the path from the taste cell to the brain
Taste cell - Gustatory afferent - medulla, Gustatory nucleus in the solitary nucleus tract - Ventral Posterior Medial Nucleus in the thalamus - Primary gustatory cortex - Hypothalamus - Amygdala
Which region of the thalamus does gustatory information pass through?
The Ventral Posterior Medial Nucleus
Which area of the medulla do gustatory neurons pass through?
The Gustatory nucleus of the solitary tract
Describe Salty transduction in taste cells
Na+ is detected by the amiloride- sensitive Na+ channels.
These sodium channels open, and the cell is depolarised.
Describe sour sensitivity in taste cells
Protons are detected by a H+ channel
The channel opens and protons rush in, depolarising the cell
By which receptor is sugar is recognised in taste cells
Sugar acts a ligand on the T1R2/T1R3 heterodimer.