L14: Sensory System: Chemical Senses Flashcards
What are the two chemical senses in humans?
Taste (gustation) and smell (olfaction).
What evolutionary advantage do chemical senses provide?
They help detect chemicals in the environment, find food, identify mates, and avoid harmful substances.
What are the five basic tastes?
Sweet, sour, salty, bitter, and umami.
What is umami, and what foods are associated with it?
Umami is a savoury taste associated with foods like mushrooms, soy sauce, and meat.
What type of receptors are involved in detecting chemical senses?
Chemoreceptors.
How does the taste system work to detect stimuli?
Chemicals bind to receptors on taste cells, causing signal transduction, which leads to neural signals sent to the brain.
How are taste buds organised on the tongue?
They are distributed across the tongue, with some areas more sensitive to certain tastes, but all areas can detect all basic tastes.
What is the lifespan of taste receptor cells?
About two weeks, after which they are replaced by basal cells.
What happens when you have a cold, and how does it affect taste?
A blocked nose reduces smell perception, which diminishes the ability to detect flavour since taste and smell combine to create flavour.
What is signal transduction in taste?
The process of converting a chemical signal (taste molecule binding) into an electrical signal (neural message).
How do humans detect salty tastes?
Sodium ions enter taste cells through non-gated channels, causing depolarization.
How do humans detect sour tastes?
Hydrogen ions from acidic substances enter cells and either block potassium channels or depolarize the cell directly.
How are sweet, bitter, and umami tastes detected?
Through G-protein-coupled receptors that trigger intracellular signalling cascades.
What is the role of the brain’s primary gustatory cortex?
It processes taste information for conscious awareness and flavour perception.
How is smell different from taste in terms of receptor cells?
Olfactory receptor cells are neurons and can fire action potentials, while taste receptor cells are not neurons.
Where are olfactory receptors located?
In the olfactory epithelium at the roof of the nasal cavity.
What is population coding in smell?
The process by which the brain decodes patterns of activity from multiple olfactory neurons to identify specific smells.
Why does smell have a strong association with memory and emotion?
Olfactory signals are processed in the limbic system, which is involved in emotions and memory.
What is anosmia?
The loss of the sense of smell, which can occur due to damage to olfactory pathways or the brain.
How do the taste and smell pathways differ in the brain?
The olfactory pathway bypasses the thalamus initially, while the gustatory pathway does not.
How do taste and smell combine to create flavour?
Flavour is the result of both taste and smell information converging in the brain, along with texture and other sensory inputs.
What is the primary purpose of bitterness detection in taste?
To help avoid toxic substances, which are often bitter.
What happens to taste cells if damaged by hot or abrasive food?
They regenerate, as basal cells produce new taste receptor cells every two weeks.
Why do older individuals often experience a decline in their sense of taste?
The rate of taste receptor cell replacement slows down with age.
