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
What are some functions of taste recognition?
1. Guide a____
2. Trigger p____ processes for absorbing n____ and adjusting m____
Guide appetite, trigger physiological processes for absorbing nutrients and adjusting metabolism
What are two tastes and meanings that are greatly influenced by culture?
Good taste = usually good
Bad or bitter taste = potentially harmful
Define taste
Detection of c____ c____ in the mouth by d____ c____ with c____ on the t____ and the r____ of the m____
Detection of chemical compounds in the mouth by direct contact with chemoreceptors on the tongue and the roof mouth
What is retronasal olfactory sensation?
Perception of o____while c____ and s____ food
Perception of odorants while chewing and swallowing food
Odor sensations are perceived as originating from the mouth, even though the actual contact of odorant and receptor occurs where?
At the olfactory mucosa
Fill in the gaps about the structure and function of taste sensation…
1. Taste receptors are arranged in____ _____, distributed along the t____, p_____, p______, e_____, and upper third of the o_______.
2. Taste buds arranged in three kind of _____, distributed in specific _____ of the tongue.
3. Receptors for different tastes _____ together in the same _____.
4. Receptor activation sends _____ _______ through taste nerves
- taste buds, tongue, palate, pharynx, epiglottis, oesophagus
- papillae, regions
- group, bud
- Neural signal
Fill in the gaps about taste buds and taste receptors…
1. Each taste bud contains several types of taste r____ c___.
2. Receptor cells are s______ cells containing m_______, containing r______ p______.
3. T_____ main receptor types according to their function.
4. Type I: s______ function.
5. Type II: detect b_____, s_____ and u_____. Chemical signal to n________ cells (including Type III).
6. Type III: detect s____. Synaptic communication with a______ fibers
- receptor cells
- specialised, microvilli, receptor proteins
- three
- support
- bitter, sweet, umami, neighbouring
- Sour, afferent
What are the G-coupled protein taste receptors? What do they detect?
TR____ and TR____
TR____ detects s____ and u____ taste
TR____ detects b____ taste
TR1 and TR2
TR1 detects sweet and umami taste
TR2 detects bitter taste
(Ion (Na+) channel ENaC detects salty)
What are the three cranial nerves that detect taste information?
1. Ch____da ty____ni
2. Gl____so-ph____geal
3. Va____
- Chorda tympani
- Glosso-pharyngeal
- Vagus
What responses do the following tastes evoke in humans?
1. Bitter
2. Sour
3. Sweet and salty
- May signal poisonous food
- May be related to acidic substances that may cause damage
- Induce seeking behaviour since such substances increase survival
