sensing the world : chemical senses Flashcards
What are the two main chemical senses?
Smell (olfaction) and taste (gustation).
How do chemical senses influence behaviour?
They motivate emotional behaviours, detect dangers, find food, and support social interactions.
What behaviours do olfactory cues support?
Food seeking, mating, territory marking, co-specific identification, aggression, and early warnings.
How does human olfaction compare to dogs’?
Human receptors are as sensitive, but humans have fewer receptors than dogs.
Can humans scent-track?
Yes, at least for some behaviours.
What is the primary function of the human nose?
Humidify and warm the air entering the lungs.
What is the secondary function of the nose?
Olfaction (sense of smell).
What captures odorants in the nose?
Mucus in the olfactory epithelium.
What do Olfactory Sensory Neurons (OSNs) do?
Detect odours and produce mucus.
How do olfactory receptors work?
Odorants bind to G-protein coupled receptors on OSN cilia, opening Na+/Ca2+ channels and depolarising the neuron.
Where do OSN axons project?
Through the cribriform plate to glomeruli in the olfactory bulb.
What happens in the olfactory bulb?
OSN axons synapse with mitral and tufted cells, projecting to the primary olfactory cortex and other brain areas.
How many odour receptors do humans have?
About 1000 different types.
How can humans perceive over a trillion odours?
Through unique activation patterns of multiple receptors (shape-pattern theory).
What factors influence olfactory detection thresholds?
Gender, training, and age.
What does taste recognition guide?
Appetite and nutrient absorption.
What do bitter or sour tastes typically signal?
Potentially harmful substances.
How early do taste preferences appear?
They are already present in newborns.
What is taste?
Detection of chemical compounds in the mouth by chemoreceptors.
What is retronasal olfactory sensation?
Perception of odours while chewing and swallowing.
What is flavour?
A combination of taste and retronasal olfaction.
Where are taste buds found?
Tongue, palate, pharynx, epiglottis, and upper oesophagus.
How are taste buds arranged?
In three kinds of papillae, distributed across specific tongue regions.
What do taste receptor cells contain?
Microvilli with receptor proteins.
