L16 - Smell, Taste, Hearing and Touch Flashcards
Location of Olfactory receptors
Dendrites facing outside world
What is the glomerulus?
Neurons that express the same receptor type will converge onto the same place in the brain
What type of receptors are human olfactory?
GPCRs: Odourant binding leads to opening of a cyclic nucleotide-gated channel and depolarisation of olfactory receptor neurons Insects are ion channels
What is combinational coding?
each neurons is activated by many odorants – combinatorial code
Direction of stimulus and info in olfactory?
Same
5 survival tastes
- Bitter = avoid poisons
- Sweet = sugar & carbohydrate
- Umami = l-amino acids (monosodium glutamate)
- Salty = Na+
- Sour = acids/H+
- Fat – the sixth taste? Repel or attract
where are the receptors? (3)
o Circumvallate (back) o Foliate (Middle) o Fungiform (front)
What are taste receptor cells (TRCs)?
neuroepithelial cells and can regenerate Clusters of TRCs form taste buds. Taste cells release neurotransmitter that activate terminal branches of gustatory nerves
Hearing
Air pressure Insects - speed of moving particles
Normal range for hearing?
20 to 20,000 Hx
Auditory system:4
o External ear o Middle ear (bones: malleus, incus, stapes) o Inner ear (cochlea) o Detect sounds
Vestibular system: 3
o Semicircular canals (posterior, horizontal, anterior) o Otolith organs (utricle, saccule) o Detect gravity, acceleration and head rotation.
cochlea (Outer/Inner hairs)
Sound into electrical signals • Outer hair cells provide active amplification, inner hair cells send signal to the brain.
What molecules changes shape of outer hair?
prestin
Role of K in hearing
Stereocilia on the apical side of the hair cells Mechanical force will pull on the channel and physically opens it, allowing K+ in and leading to depolarization = very fast
