Chapter 3 - Hair Cell Transduction Flashcards
What is the first step in hair cell transduction?
The overall process can be broken down into six steps. The first step involves (1) Hair-bundle deflections result in the opening and closing of mechanoelectric transducer (MET) channels, which carry a depolarizing transducer current. In this process, tip links on hair cells linking protocadherin, and TMC1 open and allow calcium influx into the stereocilia.
After depolarization and the opening of the mechanoelectric transduction channels, what happens in the hair cell?
The overall process can be broken down into six steps. (2) The depolarization leads to the opening of K + and Ca 2 + channels in the basolateral plasmalemma. The resulting currents shape receptor potentials, each hair cell’s voltage response to hair-bundle deflections.
After opening of mechanoelectric transduction channels and the subsequent influx of calcium and potassium, what is the next step in hair cell transduction?
(3) In addition, the currents flowing through the Ca 2 + channels regulate several cellular processes, including neurotransmitter release.
What is the afferent neurotransmitter, and how is it’s release triggered?
(4) Glutamate is the afferent neurotransmitter and is packaged in vesicles in the proximity of presynaptic synaptic bodies (SBs) at ribbon synapses. An increase in cytosolic Ca 2 + facilitates exocytosis, the fusion of vesicles with the plasmalemma and the release of neurotransmitter, which diffuses across the synaptic cleft and attaches to postsynaptic receptors.
Once glutamate is released from the presynaptic terminal, how is the signal carried forward?
(5) Sustained neurotransmitter release depolarizes the afferent terminal. (6) The “spike encoder,” a set of conductances in the afferent terminal, converts the postsynaptic depolarization into a train of action potentials, which is transmitted to the brain.
