Chemical senses Flashcards
What are the two chemical senses?
Smell and taste
What two things are influenced by the presence of chemical signals?
____ and ____ behavioural ____
Motivated and emotional behavioural responses
What three things are odours key in detecting?
- Potential dangers
- Opportunities for food
3… or social interactions
What two things does flavour help in identification of?
- Specific foods and food quality
- Support learning associations between tastes and emotional events
What are some diverse behaviours that olfactory cues support?
- Food or mate seeking
- Feeding
- Co-specific identification (group or non-group)
- Marking territories
- Reproduction
- Aggression and early warning
Compare how relevant smell is to humans and dogs
Dogs can detect odors 100x less concentrated than humans can
Receptors equally sensitive - respond to one single odor molecule
Dogs have 100x more receptors
What is the primary and secondary function of the human nose?
Primary = humidify and warm air going into lungs
Secondary = Olfaction
How does the nose capture odorants?
Air flows into nose cavity
Odorants interact with olfactory epithelium
Mucus in epithelium captures odorants
What are the three types of cell in the olfactory epithelium?
1. S____ cells - ____ and ____ support
2. B____ cells - olfactory cell ____
3. O____ s____ n____ - detect ____ and produce ____
- Supporting, metabolic, physical
- Basal, progenitors
- Olfactory sensory neurons, odors, mucus
Finish the sentences about olfactory receptors…
1. Odorants are recognised by _______ receptors in the ______ of OSNs
2. ________ receptors are G-coupled ________ whose activation opens ____/____ channels
3. OSN is _______ by Na+/Ca2+ influx, firing _____ _________
- specific, cilia
- Olfactory, proteins, Na+/Ca2+
- depolarised, action potentials
Fill in the gaps about olfactory pathways…
1. A_____ from OSNs pass through the tiny holes in the c________ plate (bone) to enter the brain.
2. Each type of OSN p______ its axon to a single g________ within the olfactory b______.
3. OSN axons make synapsis with m______ and t______ cells, that project to the p______ o______ c______ and other brain regions
- Axons, cribriform
- projects, glomerulus, bulb
- mitral, tufted, primary olfactory cortex
Humans have around 1000 different odor receptors, but how many different odorants can they receive?
Around a trillion
What is the shape pattern theory?
Each ____ activates a ____ array of olfactory ____ in the olfactory ____
These various arrays produce specific ____ patterns of neurons in the olfactory ____, which then determines the ____ we perceive.
scent
unique
receptors
epithelium.
firing
bulb
scent
Olfaction is a subjective experience. What are some factors detection threshold can be affected by?
Gender - women generally lower thresholds than men, especially during ovulatory period of menstrual cycles
Training - professional perfumers and wine tasters can distinguish up to 100,000 odorants
Age - by 85, 50% of population is effectively anosmic (sense of smell loss)
Smell means detector of changes. What does smell stop during? Why does this happen?
Continuous exposure to odorant
Due to receptor adaptation - continuous exposure to odourant makes the receptor stop responding and detection ceases
Mechanism - receptor internalisation or Na+/Ca2+ channel inactivation in the olfactory sensory neuron