Sensory Systems - 4 Senses Flashcards
What is the scientific term for the sense of smell?
Olfaction
Olfaction is the process of detecting and identifying odors.
What is the scientific term for the sense of taste?
Gustation
Gustation refers to the perception of taste through taste buds.
What is the range of normal hearing frequencies in Hertz (Hz)?
20Hz to 20,000Hz
This range varies among individuals and can be affected by age and exposure to noise.
What type of neurons are involved in the olfactory system?
Olfactory receptor neurons - each one activated (triggers action potential) by different odorants
Olfactory cilia - where olfactory receptor neurons are located
Olfactory bulb
Olfactory epithelium - located at the top of the nasal cavity
Glomerulus
What is the role of GPCRs in the olfactory system?
Olfactory receptors are GPCRs
Odorant binding leads to opening of a cyclic nucleotide-gated channel and depolarisation of olfactory receptor neurons
What does combinatorial coding in olfaction refer to?
Each odorant binds to various receptors and activates many neurons and in turn, each neuron is activated by many odorants (have varying affinities)
This results in a unique pattern of activation that allows for the perception of different smells.
What are the five basic tastes related to survival?
- Bitter = avoid poisons
- Sweet = sugar & carbohydrate
- Umami = l-amino acids (monosodium glutamate)
- Salty = Na+
- Sour = acids/H+
There is debate about whether fat should be considered a sixth taste.
What are the three types of papillae involved in taste?
Structures in which taste buds are found
- Fungiform (at the front)
- Foliate (side regions)
- Circumvallate (at the back)
What are the main components of the auditory system?
- External ear
- Middle ear (bones: malleus, incus, stapes)
- Inner ear (cochlea)
These components work together to transmit sound waves to the brain.
What is the function of hair cells in the cochlea?
Transduce sound into electrical signals
Outer hair cells provide active amplification
Inner hair cells send signals to the brain
Hair cells are crucial for converting mechanical sound vibrations into neural signals.
What is tonotopy in the cochlea?
Tonotopic representation of sound due to the properties of the basilar membrane (wider and less stiff in the apex)
It refers to the spatial arrangement of where sounds of different frequency are processed in the cochlea.
What do otolith organs detect?
Force of gravity and acceleration
These organs are crucial for balance and spatial orientation.
What are the types of mechanoreceptors involved in touch?
- Merkel cells
- Ruffini endings
= slowly adapting —> fire throughout stimulus - Meissner’s corpuscles
- Pacinian corpuscles
= rapidly adapting —> fire at onset and offset of stimulus - Free nerve endings
What type of channel is associated with sour taste?
H+ selective ion channel
This channel allows protons (H+) to enter taste receptor cells, contributing to the sour taste sensation.
Fill in the blank: The outer hair cells in the cochlea provide _______.
active amplification
Outer hair cells enhance the sensitivity of the auditory system.
True or False: The vestibular system includes semicircular canals and otolith organs.
True
These structures are essential for balance and orientation in space.
What is the primary function of the gustatory cortex?
Process taste information
It is located in the insular and frontal lobes of the brain.
What ions are involved in the depolarization of olfactory receptor neurons?
- Na+
- Ca2+
These ions flow into the neurons upon activation by odorants.
What is the function of the auditory cortex?
Process auditory information
The auditory cortex is located in the temporal lobe.
What type of channel do taste receptor cells use for sweet and umami tastes?
GPCRs and TRP channels
These channels facilitate the detection of sweet and savory flavors.
What is the main role of nociceptors?
Detect high-threshold pain stimuli
Nociceptors are specialized sensory neurons that respond to potentially damaging stimuli.
Structure of smell periphery
Olfactory sensory neurons project endings to the glomeruli located in the olfactory bulb
Information from the olfactory is conveyed to higher order brain centres via the mitral cells
Describe the mechanism of GPCRs in smell
- GDP is exchanged for GTP = activates Adenylate cyclase
- ATP produces cAMP which opens channels
- Depolarisation occurs due to influx of Ca2+ and Na+ into the olfactory receptor
Describe the different taste receptors
GPRs
Generally activated by organic compounds
Umami = T1R1 + T1R3
Sweet = T1R2 + T1R3
Bitter = ~30 T2Rs
Mineral tastes
Sour = OTOP1 —> H+ selective ion channel
Sodium = ENaC —> Epithelial Na+ channel (in mice not humans)
Receptor for far not isolated yet
