Describe the sequence of events that results in an action potential in a sensory neurone, using a chemoreceptor cell in a human taste bud as an example

SouravNovember 1, 2024

Answer

The process by which a chemoreceptor cell in a human taste bud generates an action potential in a sensory neuron involves several key steps:

1. Detection of Chemical Stimulus:
   • Chemoreceptor cells, known as gustatory cells, are located within taste buds on the tongue. These cells have microvilli that extend into the taste pore, where they come into contact with dissolved food chemicals.
2. Activation of Receptor Proteins:
   • The microvilli contain receptor proteins specific to certain taste stimuli, such as sweet, sour, salty, bitter, or umami. When a chemical stimulus binds to its corresponding receptor, it activates intracellular signaling pathways.
3. Generation of Receptor Potential:
   • Activation of these receptors leads to changes in the cell’s membrane potential, known as the receptor potential. For example, in the case of salty taste, sodium ions (Na⁺) enter the chemoreceptor cell, causing depolarization.
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4. Release of Neurotransmitters:
   • If the receptor potential reaches a certain threshold, it triggers the opening of voltage-gated calcium channels. Calcium ions (Ca²⁺) enter the cell, facilitating the exocytosis of synaptic vesicles containing neurotransmitters. These neurotransmitters cross synapses to activate sensory neurons.
5. Activation of Sensory Neuron:
   • The neurotransmitter binds to receptors on the sensory neuron’s dendrites, leading to depolarization and the generation of an action potential in the sensory neuron.
6. Transmission to the Central Nervous System:
   • The action potential travels along the sensory neuron’s axon to the brainstem, where it is relayed to higher brain centers for processing and perception.

This sequence ensures that chemical stimuli from the environment are converted into electrical signals, allowing the brain to interpret and respond to different tastes.